JPWO2006095868A1 - Content data transmitting apparatus, content data transmitting method and remote reproduction system - Google Patents

Abstract

Before receiving the content data transmission request transmitted from the reception device (90), the transmission device (60) decodes and decodes the transmission start portion of the content data held by the hard disk drive (61), and the communication environment Encoding is performed at an encoding rate according to, and further encrypted. Then, the transmission start portion of the content data subjected to such processing is held in the transmission start portion holding RAM (66). Thus, when the content data transmission request is received, the transmission device (60) first transmits the transmission start portion of the content data held in the RAM (66) to the reception device (90).

Description

  The present invention remotely communicates between a transmission device and a reception device, transmits content data stored in the transmission device to the reception device in accordance with a remote operation from the reception device, and reproduces the content data in the reception device. The present invention relates to a reproduction system, a transmission apparatus suitable for use in a remote reproduction system, and a content data transmission method.

  Currently, AV (Audio Visual) devices and Internet home appliances having a function of performing information communication by connecting to a communication network such as the Internet are being developed. For example, an audio / video recorder having an information communication function is being developed. On the other hand, mobile terminals having a function of performing information communication by connecting to a mobile communication network such as a mobile phone network or a wireless local area network (LAN) have become widespread. For example, cellular phones, PDAs (Personal Digital Assistance), car navigation devices, mobile personal computers, and the like are widely used.

  As mobile terminals have become widespread and AV devices having information communication functions are being developed, development of a remote playback system is in progress. The remote playback system generally performs wireless communication between a transmission device such as an AV device and a reception device such as a mobile terminal, transfers content data such as music or movies and other information from the transmission device to the reception device, and receives the information. The system reproduces this information in the device. According to the remote reproduction system, the user can easily view music or movies outdoors.

  Streaming will be adopted for remote playback systems. According to the remote reproduction system employing streaming, the transmission device transmits content data to the reception device, and the reception device immediately reproduces the content data while receiving the content data. According to such a remote playback system, as will be described below, the user can more easily view music or movies outdoors. For example, a transmission device is provided with a hard disk having a large recording capacity, and long-term movie content data is recorded on the hard disk. A user who is outdoors operates the receiving device and requests the transmitting device to transmit movie content data recorded on the hard disk of the transmitting device. In response to this, the transmission device transmits the movie content data recorded on the hard disk to the reception device. The receiving device includes a buffer memory having a small recording capacity. The receiving device receives the movie content data transmitted from the transmitting device, and immediately reproduces it while storing it in the buffer memory. The receiving device is provided with a liquid crystal display, for example, and the reproduced movie content data is displayed on the liquid crystal display. The receiving apparatus only includes a communication interface, a decoder, a buffer memory with a small recording capacity, a simple operation panel, a liquid crystal display, and the like. Therefore, the receiving apparatus is small in size, light in weight, and low in power consumption. According to the remote playback system, a user can easily enjoy a long-time movie outdoors with a portable and easy-to-handle receiving device.

  By the way, in the remote reproduction system, it is planned that the user takes the receiving device outdoors and views movies or music outdoors. There are various outdoor communication environments. For example, the communication environment differs greatly between when the receiving apparatus is in a large park and between buildings. Therefore, one of the development goals of the remote playback system is to maintain good transmission of content data in various communication environments and to always realize stable playback. As a means for achieving this goal, a technology has been developed in which a transmitting apparatus encodes content data at an encoding rate according to the quality of the communication environment and transmits the encoded content data to the receiving apparatus. Has been. For example, when the communication environment is good, the transmission device increases the encoding rate and transmits content data with a low compression rate to the reception device. In this case, the amount of content data transmitted from the transmission device to the reception device increases. As a result, although the quality of the video reproduced in the receiving device increases, it becomes difficult to transmit the content data from the transmitting device to the receiving device without error. However, when the communication environment is good, such a transmission often works well. On the other hand, when the communication environment is bad, the transmission device lowers the encoding rate and transmits content data with a high compression rate to the reception device. In this case, the amount of content data transmitted from the transmission device to the reception device is reduced. As a result, although the quality of the video reproduced in the receiving device is low, it becomes easy to transmit content data from the transmitting device to the receiving device without error. Therefore, even if the communication environment is bad, transmission will be successful.

  In a remote reproduction system that employs such a technique, the content data is encoded at an encoding rate according to the communication environment before the transmission device transmits the content data to the reception device. If the transmission device receives the content data transmission request from the reception device, then the content data to be transmitted is encoded, and then the content data is transmitted to the reception device, the transmission device receives the content data. The time from when the content data transmission request is received from the apparatus until the actual transmission of the content data is increased by the time for executing the encoding. This extension of time appears as a delay from when the user performs an operation for starting the reproduction of the content data until the actual reproduction of the content data is started. Such a delay may cause undesirable problems such as making the user feel unresponsive.

  On the other hand, in a remote reproduction system, content data such as a movie or music protected by copyright may be transmitted from a transmission device to a reception device. In addition, content data that the user wants to keep secret may be transmitted. When a public network such as the Internet or a mobile phone network is used as a communication network between the transmission device and the reception device, there is a risk that content data may be intercepted by others. If such a risk is left unattended, copyright protection is eroded or the user cannot keep secret. Therefore, another development goal of the remote reproduction system is to increase the confidentiality of the content data. As one means for achieving this goal, a technique for encrypting content data in a transmission device and transmitting the encrypted content data to a reception device has been developed.

  In a remote reproduction system that employs such a technique, content data is encrypted before the transmission device transmits the content data to the reception device. If the transmitting device receives the content data transmission request from the receiving device, encrypts the content data to be transmitted, and then transmits this content data to the receiving device, the transmitting device The time from when the content data transmission request is received from the receiving apparatus until the actual transmission of the content data is increased by the time for executing the encryption. This extension of time appears as a delay from when the user performs an operation for starting the reproduction of the content data until the actual reproduction of the content data is started. Such a delay may cause an undesirable problem such as making the user feel inoperable or troublesome.

  A similar problem occurs when the content data recorded on the hard disk of the transmission device is encrypted in advance and the content data needs to be decrypted before the transmission device transmits the content data to the reception device. obtain. In addition, the problem is that the content data recorded on the hard disk of the transmission device is compressed in advance, and the content data needs to be expanded (decompressed / restored) before the transmission device transmits the content data to the reception device. It can also happen.

  The present invention has been made in view of the problems as exemplified above, and the first problem of the present invention is that a transmission device that has excellent response, excellent operability, or does not make the user feel bothersome of operation, A remote reproduction system, a content data transmission method, and a computer program are provided.

  A second problem of the present invention is that a transmission device, a remote reproduction system, and a content that can shorten the time from when a user performs an operation to start reproduction of content data until the actual reproduction of content data is started To provide a data transmission method and a computer program.

  A third object of the present invention is to provide a transmission apparatus, a remote reproduction system, a content data transmission method, and a transmission apparatus capable of reducing the time from when a transmission apparatus receives a content data transmission request until transmission of content data is started. To provide a computer program.

  In order to solve the above-described problem, the first transmission device of the present invention receives the content data in response to a content data transmission request transmitted from the reception device in order to reproduce the content data by streaming in the reception device. A first data holding unit that holds content data, and the content data transmission request is received from when the content data held by the first data holding unit can be encoded. An encoding unit that encodes a transmission start portion of the content data held by the first data holding unit and a transmission of the content data encoded by the encoder unit during a transmission waiting period included in a period until the time of being transmitted Second data holding means for holding a start portion; Receiving means for receiving a content data transmission request transmitted from the receiving device; and when the content data transmission request is received by the receiving means, a transmission start portion of the content data held by the second data holding means Transmitting means for transmitting to the receiving device.

  In order to solve the above problems, a first remote reproduction system of the present invention includes a transmission device and a reception device connected to each other via a network, and the first remote reproduction system according to a content data transmission request transmitted from the reception device. A remote reproduction system in which a transmission device transmits content data to the reception device, and the reception device reproduces the content data by streaming, wherein the transmission device includes first data holding means for holding content data; During the transmission standby period included in the period from the time when the content data held by the first data holding means can be encoded to the time when the content data transmission request is received, the first data holding means Encoding means for encoding a transmission start portion of the held content data; Second data holding means for holding a transmission start portion of the content data encoded by the coder means, receiving means for receiving a content data transmission request transmitted from the receiving device, and the content data transmission request by the receiving means Transmission means for transmitting the transmission start part of the content data held by the second data holding means to the receiving device.

  In order to solve the above-described problem, the first content data transmission method of the present invention is configured to replay the content data in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device. A content data transmission method in a transmission device that transmits to a reception device, a period from when it is possible to encode content data held in the first data holding unit to when the content data transmission request is received The first encoding step for encoding the transmission start portion of the content data held in the first data holding unit during the transmission standby period included in the transmission, and the transmission start portion of the content data encoded in the first encoding step Holding data in the second data holding unit And degree, when the content data transmission request is received, and a first transmission step of transmitting a transmission start portion of the content data stored in the second data holding unit to the receiving device.

  In order to solve the above-described problem, the second transmission device of the present invention is configured to receive the content data in response to a content data transmission request transmitted from the reception device in order to reproduce the content data by streaming in the reception device. A first data holding means for holding content data, and the content data transmission request from the time when the content data held by the first data holding means can be encrypted. An encryption means for encrypting a transmission start portion of the content data held by the first data holding means during the transmission waiting period included in a period until the time of reception; and the encryption means encrypted by the encryption means Second data holding means for holding a transmission start portion of the content data, and transmission from the receiving device Receiving means for receiving the received content data transmission request, and when the content data transmission request is received by the receiving means, the transmission start portion of the content data held by the second data holding means is transmitted to the receiving device. Transmitting means.

  In order to solve the above-described problem, a second remote reproduction system of the present invention includes a transmission device and a reception device that are connected to each other via a network, and in response to a content data transmission request transmitted from the reception device. A remote reproduction system in which a transmission device transmits content data to the reception device, and the reception device reproduces the content data by streaming, wherein the transmission device includes first data holding means for holding content data; During the transmission waiting period included in the period from when the content data held by the first data holding means can be encrypted to when the content data transmission request is received, the first data holding means Encrypting means for encrypting the transmission start part of the content data held by the Second data holding means for holding a transmission start portion of the encrypted content data, receiving means for receiving a content data transmission request transmitted from the receiving device, and receiving the content data transmission request by the receiving means And a transmission means for transmitting the transmission start portion of the content data held by the second data holding means to the receiving device.

  In order to solve the above-described problem, the second content data transmission method of the present invention provides the content data in response to a content data transmission request transmitted from the reception device in order to reproduce the content data by streaming in the reception device. A content data transmission method in a transmission device that transmits to a reception device, from when the content data held in the first data holding unit can be encrypted to when the content data transmission request is received An encryption step for encrypting a transmission start portion of the content data held in the first data holding unit during a transmission standby period included in the period, and transmission start of the content data encrypted in the encryption step A data holding step of holding the portion in the second data holding unit, and the content data When the signal request is received, the transmission start portion of the content data stored in the second data holding unit and a transmitting step of transmitting to the receiving device.

  In order to solve the above-described problem, the third transmission device of the present invention is configured to receive the content data in response to a content data transmission request transmitted from the reception device in order to reproduce the content data by streaming in the reception device. A first data holding unit that holds encrypted content data, and the encrypted content data held by the first data holding unit can be decrypted. Decryption for decrypting the transmission start portion of the encrypted content data held by the first data holding means during the transmission standby period included in the period from the time until the content data transmission request is received And a second data holding a transmission start portion of the content data decrypted by the decrypting means. Content holding means, receiving means for receiving a content data transmission request transmitted from the receiving device, and content data held by the second data holding means when the content data transmission request is received by the receiving means Transmitting means for transmitting the transmission start portion of the transmission to the receiving device.

  In order to solve the above-described problem, a third remote reproduction system of the present invention includes a transmission device and a reception device connected to each other via a network, and in response to a content data transmission request transmitted from the reception device, A remote reproduction system in which a transmission device transmits content data to the reception device, and the reception device reproduces the content data by streaming, the transmission device holding first data holding encrypted content data And a transmission waiting period included in a period from when the encrypted content data held by the first data holding means can be decrypted until when the content data transmission request is received In addition, the transmission start portion of the encrypted content data held by the first data holding means is decrypted. Decoding means, second data holding means for holding a transmission start part of the content data decoded by the decoding means, receiving means for receiving a content data transmission request transmitted from the receiving device, A transmission unit configured to transmit a transmission start portion of the content data held by the second data holding unit to the receiving device when the content data transmission request is received by the receiving unit;

  In order to solve the above-described problem, a third content data transmission method according to the present invention provides the content data in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device. A content data transmission method in a transmission device for transmission to a reception device, wherein the content data transmission request is received from when encrypted content data held in a first data holding unit can be decrypted. A decryption step of decrypting the transmission start portion of the encrypted content data held in the first data holding unit during the transmission waiting period included in the period until the time when Data holding step of holding the transmission start portion of the content data that has been received in the second data holding unit , When the content data transmission request is received, and a transmission step of transmitting a transmission start portion of the content data stored in the second data holding unit to the receiving device.

  In order to solve the above-described problem, the fourth transmission device of the present invention is configured to receive the content data in response to a content data transmission request transmitted from the reception device in order to reproduce the content data by streaming in the reception device. A first data holding unit that holds compressed content data, and the compressed content data held by the first data holding unit can be expanded A decompression unit for decompressing a transmission start portion of the compressed content data held by the first data holding unit during a transmission standby period included in a period until a content data transmission request is received; Second data holding means for holding a transmission start part of the content data expanded by Receiving means for receiving a content data transmission request transmitted from the receiving device; and when the content data transmission request is received by the receiving means, a transmission start portion of the content data held by the second data holding means Transmitting means for transmitting to the receiving device.

  In order to solve the above problems, a fourth remote reproduction system of the present invention includes a transmission device and a reception device connected to each other via a network, and in response to a content data transmission request transmitted from the reception device, A remote reproduction system in which a transmission device transmits content data to the reception device, and the reception device reproduces the content data by streaming, wherein the transmission device holds first data holding means for holding compressed content data And during a transmission standby period included in a period from when it becomes possible to expand the compressed content data held by the first data holding means to when the content data transmission request is received, A decompressing hand that decompresses the transmission start portion of the compressed content data held by the first data holding means A second data holding unit that holds a transmission start portion of the content data expanded by the expansion unit, a receiving unit that receives a content data transmission request transmitted from the receiving device, and the content by the receiving unit And a transmission means for transmitting the transmission start portion of the content data held by the second data holding means to the receiving device when a data transmission request is received.

  In order to solve the above-described problem, a fourth content data transmission method of the present invention is configured to replay the content data in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device. A content data transmission method in a transmission device for transmission to a reception device, wherein the content data transmission request is received from when the compressed content data held in the first data holding unit can be expanded A decompression step of decompressing the transmission start portion of the compressed content data held in the first data holding unit during the transmission standby period included in the period until the transmission, and transmission of the content data decompressed in the decompression step A data holding step of holding the start portion in the second data holding unit; When Tsudeta transmission request is received, the transmission start portion of the content data stored in the second data holding unit and a transmitting step of transmitting to the receiving device.

  In order to solve the above problems, the first to fourth computer programs of the present invention cause a computer to function as the first to fourth transmission devices of the present invention.

  In order to solve the above problems, the first to fourth computer program products in the computer-readable medium clearly embody the program instructions executable by the computer, and the computer transmits the first to fourth transmissions of the present invention. It functions as an apparatus (including various aspects).

  According to each computer program product of the present invention, if the computer program product is read into a computer from a recording medium such as a ROM, CD-ROM, DVD-ROM, or hard disk storing the computer program product, or a transmission wave, for example, If the computer program product is downloaded to the computer via the communication means, the first to fourth transmission devices of the present invention described above can be implemented relatively easily. More specifically, the computer program product may be composed of computer-readable codes (or computer-readable instructions) that function as the first to fourth transmission devices of the present invention described above.

  Such effects and other advantages of the present invention will be further clarified from the embodiments and examples described below.

It is a block diagram which shows 1st Embodiment of the remote reproduction | regeneration system of this invention. It is a block diagram which shows the internal structure of the transmitter in FIG. It is a flowchart which shows operation | movement of the transmission apparatus in FIG. It is a flowchart which shows the unreproduced part detection process in FIG. It is a flowchart which shows the encoding rate setting process in FIG. It is explanatory drawing which shows the encoding operation | movement and transmission operation | movement in the transmission apparatus in FIG. 1 side by side on a time axis. It is a block diagram which shows the transmission apparatus in 2nd Embodiment of the remote reproduction | regeneration system of this invention. It is a block diagram which shows the transmission apparatus in 3rd Embodiment of the remote reproduction | regeneration system of this invention. It is a block diagram which shows the transmission apparatus in 4th Embodiment of the remote reproduction | regeneration system of this invention. It is a block diagram which shows the Example of the remote reproduction | regeneration system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 Remote reproduction system 2, 20, 30, 40, 60 Transmission apparatus 3, 90 Reception apparatus 11 1st data holding means 12 Encoding means 13 Encoding rate setting means 14 2nd data holding means 15 Reception means 16 Transmission means 17 History Recording means 18 Unreproduced part detection means 19 Switching means 21 Encryption means 31 Decoding means 41 Decompression means 62 Decryptor 63 Decoder 64 Encoder 65 Encryptor 66 Transmission start part holding RAM
67 selector 69 history recording unit 70 unreproduced part detection unit 71 encoding control unit 72 transmission control unit

  Hereinafter, the best mode for carrying out the present invention will be described in order for each embodiment with reference to the drawings.

(First embodiment of remote reproduction system)
FIG. 1 shows a first embodiment of a remote reproduction system of the present invention. As shown in FIG. 1, the remote reproduction system 1 includes a transmission device 2 and a reception device 3. The transmission device 2 and the reception device 3 are connected to each other via the communication path 4 and communicate with each other. The transmission device 2 preferably includes a recording medium having a large recording capacity. The recording medium holds content data having a large data size, such as a long movie. The receiving device 3 can remotely operate the transmitting device 2. When the reception device 3 transmits a content data transmission request to the transmission device 2, the transmission device 2 transmits content data to the reception device 3 accordingly. The receiving device 3 receives the content data transmitted from the transmitting device 2 and reproduces it. The remote reproduction system 1 employs streaming technology. The receiving device 3 includes a buffer memory, and immediately reproduces the content data while storing the received content data in the buffer memory. Furthermore, the receiving device 3 includes a display, for example. When the content data is video data, the playback video is displayed on this display.

  The content data is preferably video data or music data. The content data may be still image data, document data, numerical data, or audio data other than music.

  The transmission device 2 is preferably an AV device or a network home appliance having a function of performing information communication. For example, the transmission device 2 is an audio / video recorder having an information communication function. The transmission device 2 may be a server computer, a personal computer, other computers, or various devices equipped with computers. The transmitter 2 will be described in detail later with reference to FIGS.

  The receiving device 3 (a) transmits control information such as a content data transmission request to the transmitting device 2 and also receives a content data transmitted from the transmitting device 2, and (b) temporarily receives the received content data. (C) Decoder that reproduces received content data, (d) Display that displays reproduced video, (e) Operation to remotely control transmission device 2 such as instructing transmission of content data transmission request It is desirable to have a panel. Note that, when content data is encrypted and transmitted as in a video playback system 2 described later, the receiving device 3 includes a decryptor that decrypts the encrypted content data. The receiving device 3 is, for example, a mobile phone, a PDA, a car navigation device, or a mobile personal computer. The receiving device 3 is desirably small and excellent in portability and portability. However, the receiving device 3 may be, for example, a desktop personal computer or a telemedicine computer.

  The communication path 4 may be wired or wireless. The communication path 4 is, for example, the Internet, a computer network such as a WAN (Wide-Area Network) or a LAN (Local-Area Network), a mobile phone network, IMT-2000 (International Mobile Telecommunications-2000), or the like. According to the example of FIG. 1, the communication path 4 is a composite communication network in which the Internet 5 and a mobile phone line are connected via a base station 6 and a gateway (not shown).

  The remote reproduction system 1 has a function of setting / changing the encoding rate of content data in accordance with the communication environment between the transmission device 2 and the reception device 3. For example, when the communication environment is good, the transmission device 2 increases the encoding rate and transmits content data with a low compression rate to the reception device 3. In this case, the amount of content data transmitted from the transmission device 2 to the reception device 3 increases. As a result, although the quality of the video reproduced in the receiving device 3 is improved, it becomes difficult to transmit the content data from the transmitting device 2 to the receiving device 3 without error. However, when the communication environment is good, such a transmission often works well. On the other hand, when the communication environment is bad, the transmission device 2 lowers the encoding rate and transmits content data with a high compression rate to the reception device 3. In this case, the amount of content data transmitted from the transmission device 2 to the reception device 3 is reduced. As a result, although the quality of the video reproduced in the receiving device 3 is lowered, it becomes easy to transmit the content data from the transmitting device 2 to the receiving device 3 without error. Therefore, even if the communication environment is bad, transmission will be successful. This function is realized by the encoding rate setting means 13 (see FIG. 2) of the transmission apparatus 2 as will be described later.

  FIG. 2 shows the internal structure of the transmission apparatus 2. As shown in FIG. 2, the transmitting apparatus 2 includes a first data holding unit 11, an encoding unit 12, an encoding rate setting unit 13, a second data holding unit 14, a receiving unit 15, a transmitting unit 16, a history recording unit 17, and an unrecorded unit. A reproduction part detection means 18 is provided. Further, the transmission unit 16 includes a switching unit 19.

  The first data holding unit 11 holds content data. The first data holding unit 11 includes a recording medium and a device that reads information or data recorded on the recording medium. It is desirable that the recording medium of the first data holding unit 11 has a large recording capacity. The recording medium of the data holding means 11 is preferably non-volatile and can store information or data for a long period of time. For example, the first data holding means 11 is a hard disk and a hard disk drive. The first data holding means 11 is a magnetic medium such as a tape and a reader thereof, an optical disc such as an LD (Laser Disc), a CD (Compact Disc), a DVD, a BlueRay-Disk, and an HDDVD and a reader thereof, or a card type. A non-volatile memory such as a flash memory (memory card) and its reader may be used.

  The encoding unit 12 encodes the content data held by the first data holding unit 11. As described above, the remote reproduction system 1 has a function of setting / changing the encoding rate of content data in accordance with the communication environment between the transmission device 2 and the reception device 3. The encoding unit 12 encodes the content data in order to set an encoding rate according to whether the communication environment is good or bad. The content data held by the first data holding means 11 has already been encoded by an encoding method with a substantially high compression ratio such as MPEG2-TS (Moving Picture Experts Group phase 2-Transport Stream) or MPEG4 AVC (H.264). Even when there is a need to change the encoding rate of the content data in accordance with the quality of the communication environment, the encoding means 12 first decodes the content data, and then the quality of the communication environment. Re-encode it at an encoding rate according to. The encoding unit 12 employs a configuration in which the encoding rate is changed while maintaining the encoding method (for example, MPEG2-TS) of the content data held by the first data holding unit 11. The encoding unit 12 may adopt a configuration in which the encoding rate is substantially changed by changing the encoding method of the content data held by the first data holding unit 11. For example, a configuration in which the content data encoding method is changed from MPEG2-TS to MPEG4 AVC may be adopted. The encoding unit 12 has a function of changing the encoding rate or the encoding method, and the process of changing the encoding rate or the encoding method includes decoding. Therefore, the encoding means 12 is a complex data processing means having a decoding function in addition to a pure encoding function.

Furthermore, the encoder means 12 performs content data encoding in two different periods. That is, considering the operation of the transmitting device 2 in operation, two types of periods can be defined according to the operation of the transmitting device 2. One of them is a period during which content data is transmitted to the receiving device 3 (hereinafter referred to as “transmission period”). The other is a period of waiting for transmission of content data to the receiving device 3 (hereinafter referred to as “transmission waiting period”). Specifically, in the transmission period, immediately after the content data transmission request transmitted from the receiving device 3 is received by the transmitting device 2, the transmission of the content data to the receiving device 3 is thereby started, and this transmission is interrupted. It is a period until it stops or ends. On the other hand, the transmission standby period is from when the content data held by the first data holding unit 11 can be encoded to when the content data transmission request transmitted from the receiving device 3 is received by the transmitting device 2. Part or all of the period up to. More specifically, there are the following three typical examples of the transmission standby period.
(1) A period from immediately after the transmission device 2 is turned on to when a content data transmission request is received;
(2) A period from immediately after the content data transmission to the receiving device 3 is interrupted, stopped, or ended to when the content data transmission request is received again;
(3) When the content data to be transmitted is not held by the first data holding means 11, when the content data to be sent is held by the first data holding means 11 (for example, the transmission device 2 is connected to the digital television broadcast). When connecting to the network, receiving content data from a television broadcasting station, and recording it on the recording medium of the first data holding means 11; when the transmission device 2 has a reserved recording function, recording a reserved program The period from the start of the recording of the reserved program to the time when the content data transmission request is received;
The encoding unit 12 first encodes the transmission start portion of the content data held by the first data holding unit 11 during the transmission standby period. For example, the encoding unit 12 starts encoding the transmission start portion of the content data immediately after the transmission device 2 is turned on. Alternatively, the encoding unit 12 starts encoding the transmission start portion of the content data immediately after the transmission of the content data to the receiving device 3 is interrupted, stopped, or terminated. Alternatively, the encoding unit 12 starts encoding the transmission start portion of the content data immediately after the content data to be transmitted is recorded on the recording medium of the first data holding unit 11. Next, the encoding unit 12 encodes another part following the transmission start part in the content data held by the first data holding unit 11 during the transmission period.

  The target to be encoded by the encoding means 12 during the transmission standby period is the transmission start portion of the content data. The transmission start portion is a part of the content data that is transmitted first by the transmission device 2 during the transmission period. Specifically, the transmission start part is the head part of the unreproduced part of the content data held by the first data holding unit 11. When all of the content data has not been reproduced, the transmission start portion is the head portion of the content data. The size (range) of the transmission start portion of the content data can be determined in consideration of processing performance such as the encoding execution speed in the encoding means 12. For example, if the encoding unit 12 starts encoding the start position of the content data and completes this for 1 or 2 seconds, the transmission start portion corresponds to a playback time of 1 or 2 seconds. Part of the content data.

  The encoding unit 12 includes, for example, a combination of an encoder and a decoder, or a data processing unit (which may be a transcoder) having these functions, and a control unit (for example, an arithmetic processing circuit and a semiconductor memory) that controls the timing of encoding. Can be realized.

  The encoding rate setting unit 13 sets the encoding rate of the encoding unit 12 to be changeable. The encoding rate setting means 13 sets the encoding rate set immediately before the transmission of the content data to the receiving device 3 is interrupted, stopped or terminated as the encoding rate for encoding the transmission start portion of the content data. Is desirable. Thereby, the encoding rate according to the quality of the communication environment can be set. That is, the quality of the communication environment between the transmission device 2 and the reception device 3 is mainly determined by the communication environment around the reception device 3. For example, if the user has the receiving device 3 and is in a large park, the communication environment between the transmitting device 2 and the receiving device 3 will be good. On the other hand, if the user has the receiving device 3 and is in a building, the communication environment between the transmitting device 2 and the receiving device 3 will be bad. When a user reproduces content data by the receiving device 3 and stops or terminates the content data, the user often reproduces the content data again at the same place. If so, the communication environment is often the same between the first reproduction and the second reproduction. Therefore, by setting the encoding rate set immediately before the transmission of the content data to the receiving device 3 is interrupted, stopped, or ended as the encoding rate for encoding the transmission start portion of the content data, The encoding rate can be set according to good or bad. For the encoding rate set immediately before the transmission of the content data to the receiving device 3 is interrupted, stopped, or ended, the encoding rate set in the encoding means 12 is recorded on a recording medium, for example, and this recording is referred to You can know by doing. The encoding rate setting means 13 can be realized by, for example, an arithmetic processing unit and a semiconductor memory.

  The second data holding unit 14 holds a transmission start portion of the content data encoded by the encoder unit 12. The second data holding unit 14 includes a recording medium for holding a transmission start portion of content data. As described above, the transmission start part is a part of content data of an amount corresponding to, for example, a reproduction time of 1 second. Considering this, a recording medium having a small recording capacity (for example, several megabytes to several tens of megabytes) is sufficient as the recording medium of the second data holding unit 14. Further, the recording medium of the second data holding unit 14 may be volatile or non-volatile. The recording medium of the second data holding unit 14 is a semiconductor memory such as a RAM or a hard disk, for example. Furthermore, since the content data transmission start portion is desirably transmitted immediately after receiving the content data transmission request, it is desirable that the recording medium of the second data holding unit 14 has a high reading speed. Considering this point, the recording medium of the second data holding unit 14 is preferably a semiconductor memory.

  The receiving unit 15 receives the content data transmission request transmitted from the receiving device 3. The receiving means 15 can be realized by a network control circuit or a communication interface, for example.

  The transmission unit 16 transmits the content data encoded by the encoding unit 12 to the reception device 3. When the content data transmission request is received by the reception unit 15, the transmission device 16 performs content data transmission processing in response to the content data transmission request. There are two types of transmission processing of the transmission means 16. First, the transmission unit 16 transmits the transmission start portion of the content data held by the second data holding unit 14. Next, the transmission unit 16 transmits another part of the content data encoded by the encoding unit 12 following the transmission start part of the content data. The transmission means 16 can be realized by a network control circuit or a communication interface, for example. A transmission buffer may be provided in the transmission means 16.

  The transmission unit 16 includes a switching unit 19. The switching unit 19 switches from transmission of the content data transmission start portion held by the second data holding unit 14 to transmission of another portion following the content data transmission start portion. The switching means 19 can be realized by a selector or a switching circuit, for example.

  The history recording unit 17 records information indicating the history of content data transmitted from the transmission unit 16 to the reception device 3 and reproduced by the reception device 3 (hereinafter referred to as “reproduction history information”). The reproduction history information can be created as follows, for example. First, when the reproduction of content data is interrupted, stopped, or ended, the receiving device 3 detects the interrupted position, stop position, or end position of the content data, and transmits information indicating this to the transmitting device 2. When the interruption of the content data reproduction is an unexpected disconnection of communication due to the deterioration of the communication environment, it is difficult for the receiving device 3 to transmit information indicating the content data interruption position immediately after the interruption. In this case, information indicating the interruption position of the content data may be transmitted when communication is recovered. Subsequently, the transmission device 2 receives information indicating the interruption position, the stop position, or the end position of the content data, and records this information on the recording medium as reproduction history information. The history recording means 17 can be realized using a recording medium such as a hard disk or a semiconductor memory.

  The unreproduced part detection unit 18 detects an unreproduced part of the content data held by the first data holding unit 11 by referring to the reproduction history information. For example, the unreproduced part detection means 18 recognizes the interruption position or stop position of the content data by referring to the reproduction history information, and determines the part following the interruption position or stop position in the content data as an unreproduced part. Further, when the end position of the content data is recognized by referring to the reproduction history information, the unreproduced part detection unit 18 determines that all of the content data is an unreproduced part. When the reproduction history information is not recorded on the recording medium of the history recording unit 17, the unreproduced part detection unit 18 determines that all of the content data is an unreproduced part. The unreproduced part detection means 18 can be realized by an arithmetic processing circuit, a semiconductor memory, or the like.

  FIG. 3 shows an example of the operation of the transmission device 3. As shown in FIG. 3, when the user turns on the power of the transmission device 3, first, the unreproduced part detection unit 18 detects an unreproduced part of the content data held by the first data holding unit 11. A reproduction part detection process is performed (step S1). FIG. 4 shows an example of the unreproduced part detection process. As shown in FIG. 4, the unreproduced part detecting means 18 first checks the recording medium of the history recording means 17 and determines whether or not the reproduction history information is recorded (step S21). When the reproduction history information is recorded (step S21: YES), the unreproduced part detection unit 18 reads the reproduction history information from the recording medium of the history recording unit 17. Subsequently, the unreproduced part detecting means 18 determines whether or not the reproduction history information is information indicating the end position of the content data (step S23). When the reproduction history information is not information indicating the end position of the content data but information indicating the interruption position or stop position of the content data (step S23: NO), the unreproduced part detecting means 18 continues to the reproduction history. It is determined whether the interruption position or stop position indicated by the information is close to the end of the content data (step S24). When the interruption position or stop position is not close to the end of the content data (step S24), the non-reproduced part detection means 18 determines that the part following the interruption position or stop position in the content data is an unreproduced part (step S25). On the other hand, when reproduction history information is not recorded on the recording medium of the history recording means 17 (step S21: NO), or when the reproduction history information is information indicating the end position of the content data (step S23: YES), or When the interruption position or stop position indicated by the history reproduction information is close to the end of the content data (step S24: YES), the unreproduced part detection means 18 determines that all of the content data is an unreproduced part (step S26).

  Returning to FIG. 3, when the unreproduced part detection process is completed, the encode rate setting unit 13 performs an encode rate setting process for setting the encode rate of the encode unit 12 (step S2). FIG. 5 shows an example of the encoding rate setting process. As shown in FIG. 5, the encoding rate setting means 13 first determines whether or not a certain time (for example, about one hour) has elapsed since the transmission of the content data was interrupted, stopped, or ended (step S31). . When the transmission of the content data has been interrupted, stopped, or terminated and a certain time has elapsed (step S31: YES), the encoding rate setting unit 13 sets a predetermined default encoding rate (step S32). . On the other hand, when the fixed time has not elapsed since the transmission of the content data is interrupted, stopped, or ended (step S31: NO), the encoding rate setting unit 13 immediately before the transmission of the content data is interrupted, stopped, or ended. The set encoding rate is set (step S33).

  Returning to FIG. 3, when the encoding rate setting process is completed, the encoding means 12 then uses the beginning portion of the unreproduced portion of the content data held by the first data holding unit 11 as a transmission start portion, and encodes this. (Step S3). Subsequently, the second data holding unit 14 holds the head portion of the unreproduced portion of the encoded content data (step S4). Then, the transmission device 2 waits until the reception unit 15 receives the content data transmission request transmitted from the reception device 3 (step S5: NO).

  When the reception unit 15 receives the content data transmission request (step S5: YES), the transmission unit 16 transmits the transmission start portion of the content data held by the second data holding unit 14 to the reception device 3 (step S6). ). That is, before the receiving unit 15 receives the content data transmission request, the recording medium of the second data holding unit 14 holds the transmission start portion of the content data encoded by the encoding unit 12. The transmission unit 16 reads the transmission start portion of the content data from the second data holding unit 14 and immediately transmits it to the reception device 3.

  After the reception means 15 receives the content data transmission request, the encoding means 12 starts encoding the other part following the transmission start part of the content data almost simultaneously with the transmission of the transmission start part of the content data (step S7). . That is, the encoding means 12 reads the other part following the transmission start part of content data from the 1st data holding part 11, and begins to encode this. The other part of the encoded content data is supplied directly to the transmission means 16 without going through the second data holding means 14. When the transmission of the content data transmission start part is completed (step S8: YES), the switching unit 19 transmits the content data from the transmission of the content data transmission start part held by the second data holding unit 14. Switching to transmission of the other part following the start part (step S9). The timing at which the transmission of the transmission start portion of the content data is completed and the timing at which the head portion of the other portion of the encoded content data is supplied to the transmission means 16 are structured to match each other (for example, both The size of the transmission start part is set so that the timing matches). For this reason, transmission of the content data transmission start portion and transmission of the other portion of the content data are continuous. Even if the timings of both are slightly shifted, by providing a buffer upstream or downstream of the transmission means 16, the timing shift can be absorbed and transmission continuity can be realized.

  Furthermore, the transmission means 16 continues transmission of the other part of content data (step S10). That is, the encoding unit 12 encodes the other parts of the content data held by the first data holding unit 11 one after another, and immediately supplies this directly to the transmission unit 16. And the transmission means 16 transmits this to the receiver 3 immediately.

  Subsequently, when transmission of the other part of the content data is interrupted, stopped, or terminated (step S11: YES), the process returns to step S1.

  FIG. 6 shows the encoding operation of the encoding unit 12 and the transmission operation of the transmission unit 16 side by side on the time axis. Hereinafter, the execution timing of the encoding operation and the transmission operation will be described with reference to FIG. For convenience of explanation, description of operations of the encoding rate setting unit 13, the history recording unit 17, and the unreproduced part detection unit 18 is omitted here.

  Assume that the user turns on the power of the transmission apparatus 2 at time t0 in FIG. Immediately after this, the encoding unit 12 encodes the transmission start portion of the content data held by the first data holding unit 11 (operation A1). Note that the transmission start portion at this point is, for example, the head portion of the content data. The transmission start portion of the encoded content data is held by the second data holding unit 14. Next, it is assumed that the receiving unit 15 receives the content data transmission request transmitted from the receiving device 3 at time t1. Immediately after this, the transmitting unit 16 transmits the transmission start portion of the content data held by the second data holding unit 14 to the receiving device 3 (operation A2). At substantially the same time, the encoding unit 12 encodes another part following the transmission start part of the content data held by the first data holding unit 11 (operation A3). Next, it is assumed that the transmission of the transmission start portion of the content data held by the second data holding unit 14 is completed at time t2. At substantially the same time, the encoding of the other part of the content data is completed, and the other part of the encoded content data is directly supplied to the transmission unit 16 without passing through the second data holding unit 14. At this time, the switching means 19 switches from transmission of the content data transmission start portion held by the second data holding means 14 to transmission of another portion following the content data transmission start portion. Thereby, when the transmission of the transmission start portion of the content data is completed, the transmission of the other portion of the content data is continuously performed subsequently (operation A4). Next, it is assumed that transmission of the other part of the content data is stopped at time t3. Immediately after this, the encoding unit 12 encodes the transmission start portion of the content data held by the first data holding unit 11 (operation A5). Note that the transmission start portion at this point is the head portion of the unreproduced portion of the content data following the content data reproduction stop position. The transmission start portion of the encoded content data is held by the second data holding unit 14. At this time, the switching unit 19 switches the path so as to connect the second data holding unit 14 and the transmission unit 16. Next, it is assumed that the receiving unit 15 receives the content data transmission request transmitted from the receiving device 3 again at time t4. Immediately after this, the transmitting unit 16 transmits the transmission start portion of the content data held by the second data holding unit 14 to the receiving device 3 (operation A6). At substantially the same time, the encoding unit 12 encodes another part following the transmission start part of the content data held by the first data holding unit 11 (operation A7). Next, it is assumed that transmission of the transmission start portion of the content data held by the second data holding unit 14 is completed at time t5. At substantially the same time, the encoding of the other part of the content data is completed, and the other part of the encoded content data is directly supplied to the transmission unit 16 without passing through the second data holding unit 14. At this time, the switching means 19 switches from transmission of the content data transmission start portion held by the second data holding means 14 to transmission of another portion following the content data transmission start portion. Thereby, when the transmission of the transmission start portion of the content data is completed, the transmission of the other portion of the content data is continuously performed subsequently (operation A8).

  The important point in FIG. 6 is that the encoding operation A1 is performed during the transmission standby period corresponding to the period from the time point t0 to the time point t1. That is, the encoding operation A1 is performed before the content data transmission request from the receiving device 3 is received. Another important point in FIG. 6 is that the encoding operation A5 is performed during the transmission standby period corresponding to the period from the time point t3 to the time point t4. That is, the encoding operation A5 is executed after the content data transmission is stopped until the content data transmission request is received again.

  As described above, the transmission apparatus 2 encodes the transmission start portion of the content data during the transmission standby period before the content data transmission request is received, and holds the encoded content data by the second data holding unit 14. Then, when the content data transmission request is received, the transmission device 2 first transmits the transmission start portion of the content data that has already been encoded and is held by the second data holding unit 14. Thereby, it is possible to shorten the time from when the transmission apparatus 2 receives the content data transmission request until the transmission of the content data is started. Because the encoding of the content data transmission start portion has already been completed before the content data transmission request is received, the content data transmission request can be immediately handled without spending the encoding execution time of the content data transmission start portion. This is because the transmission start part of the content data can be transmitted. As a result, it is possible to shorten the time from when the user performs an operation for starting the reproduction of the content data until the actual reproduction of the content data is started. Therefore, it is possible to realize a remote reproduction system that does not cause the user to feel troublesome operation, has excellent response, and has excellent operability. For example, if it takes several seconds from when the user presses the playback start button of the receiving device 3 until the playback video of the content data is actually displayed on the display, the user does not respond to pressing the playback start button. You will feel and feel anxious. However, according to the video playback system 1 according to the embodiment of the present invention, the delay time from when the user presses the playback start button of the receiving device 3 until the playback video of the content data is actually displayed on the display is shortened. Therefore, the user's anxiety can be solved.

(Second embodiment of remote reproduction system)
In the second embodiment of the remote reproduction system of the present invention, the transmitting apparatus encrypts the content data and transmits it to the receiving apparatus. The receiving device reproduces the received content data by streaming while decoding the received content data.

  FIG. 7 shows the internal structure of the transmission apparatus in the second embodiment of the remote reproduction system. As shown in FIG. 7, the transmission device 20 is the same as the transmission device 1 shown in FIG. 2 except that it includes an encryption unit 21 instead of the encoding unit 12.

  The encryption unit 21 encrypts the content data held by the first data holding unit 11. The encryption unit 21 encrypts content data during two different periods. That is, like the encoding unit 12, the encryption unit 21 first encrypts the transmission start portion of the content data held by the first data holding unit 11 during the transmission standby period. Next, the encryption means 21 encrypts the other part following the transmission start part in the content data held by the first data holding unit 11 during the transmission period.

  The object to be encrypted by the encryption means 21 during the transmission standby period is the content data transmission start portion. The transmission start part is the head part of the unreproduced part of the content data held by the first data holding unit 11. When all of the content data has not been reproduced, the transmission start portion is the head portion of the content data. The size (range) of the content data transmission start portion can be determined in consideration of processing performance such as the encryption execution speed in the encryption means 21.

  The encryption means 21 can be realized by, for example, an encryptor and a control unit that controls the time when encryption is performed.

  The second data holding unit 14 holds the transmission start portion of the encrypted content data before the content data transmission request is received. When the content data transmission request is received, the transmission means 16 determines the transmission start portion of the content data that has already been encrypted at this point and is held in the recording medium of the second data holding means 14 as the second data holding means. The data is read from 14 recording media and immediately transmitted to the receiving device.

  As described above, according to the transmission device 20, it is possible to shorten the time from the reception of the content data transmission request to the start of content data transmission. Because the encryption of the content data transmission start part has already been completed before the content data transmission request is received, the content data transmission request can be made without spending the encryption execution time of the content data transmission start part. This is because the transmission start part of the content data can be transmitted immediately. As a result, it is possible to shorten the time from when the user performs an operation for starting the reproduction of the content data until the actual reproduction of the content data is started. Therefore, it is possible to realize a remote reproduction system that does not cause the user to feel troublesome operation, has excellent response, and has excellent operability.

(Third embodiment of remote reproduction system)
In the third embodiment of the remote reproduction system of the present invention, the transmitting apparatus holds content data encrypted in advance. The transmitting device decrypts the content data and transmits it to the receiving device. The receiving device reproduces the received content data by streaming.

  FIG. 8 shows the internal structure of the transmitting apparatus in the third embodiment of the remote reproduction system. As shown in FIG. 8, the transmission device 30 includes a decryption unit 31 instead of the encoding unit 12, and content data held in the first data holding unit 11 is encrypted in advance. Is the same as the transmission apparatus 1 shown in FIG.

  The decrypting unit 31 decrypts the encrypted content data held by the first data holding unit 11. The decryption means 31 decrypts the content data in two different periods. That is, like the encoding unit 12, the decrypting unit 31 first decrypts the transmission start portion of the encrypted content data held by the first data holding unit 11 during the transmission standby period. Next, the decryption means 31 decrypts the other part following the transmission start part in the encrypted content data held by the first data holding unit 11 during the transmission period.

  The object to be decrypted by the decrypting means 31 during the transmission waiting period is the transmission start portion of the content data. The transmission start part is the head part of the unreproduced part of the content data held by the first data holding unit 11. When all of the content data has not been reproduced, the transmission start portion is the head portion of the content data. The size (range) of the content data transmission start portion can be determined in consideration of processing performance such as the decryption execution speed in the decryption means 31.

  The decoding unit 31 can be realized by, for example, a decryptor and a control unit that controls the timing of decoding.

  The second data holding unit 14 holds a transmission start portion of the decrypted content data before the content data transmission request is received. When the content data transmission request is received, the transmission means 16 uses the second data holding means to indicate the transmission start portion of the content data that has already been decrypted at this point and is held in the recording medium of the second data holding means 14. The data is read from 14 recording media and immediately transmitted to the receiving device.

  As described above, according to the transmission device 30, it is possible to reduce the time from the reception of the content data transmission request to the start of content data transmission. Because the decryption of the content data transmission start part has already been completed before receiving the content data transmission request, the content data transmission request can be made without spending the decoding execution time of the content data transmission start part. This is because the transmission start part of the content data can be transmitted immediately. As a result, it is possible to shorten the time from when the user performs an operation for starting the reproduction of the content data until the actual reproduction of the content data is started. Therefore, it is possible to realize a remote reproduction system that does not cause the user to feel troublesome operation, has excellent response, and has excellent operability.

(Fourth embodiment of remote reproduction system)
In the fourth embodiment of the remote reproduction system of the present invention, the transmission device holds content data compressed in advance. The transmitting device decompresses the content data and transmits it to the receiving device. The receiving device reproduces the received content data by streaming.

  FIG. 9 shows the internal structure of the transmission apparatus in the fourth embodiment of the remote reproduction system. As shown in FIG. 9, the transmission device 40 includes an expansion unit 41 instead of the encoding unit 12 and the content data held in the first data holding unit 11 is compressed in advance. This is the same as the transmission device 1 shown in FIG.

  The decompressing unit 41 decompresses the compressed content data held by the first data holding unit 11. The decompression unit 41 decompresses content data during two different periods. That is, like the encoding unit 12, the decompressing unit 41 first decompresses the transmission start portion of the compressed content data held by the first data holding unit 11 during the transmission standby period. Next, the decompressing means 41 decompresses the other part following the transmission start part in the compressed content data held by the first data holding unit 11 during the transmission period.

  The target to which the decompression means 41 decompresses during the transmission standby period is the content data transmission start portion. The transmission start part is the head part of the unreproduced part of the content data held by the first data holding unit 11. When all of the content data has not been reproduced, the transmission start portion is the head portion of the content data. The size (range) of the content data transmission start portion can be determined in consideration of processing performance such as the decompression execution speed in the decompression means 41.

  The decompression means 41 can be realized, for example, by a unit including a processing circuit and a semiconductor memory in which a decompression control program is stored and a control unit that controls the timing of decompression.

  The second data holding unit 14 holds the transmission start portion of the decompressed content data before the content data transmission request is received. When the content data transmission request is received, the transmission means 16 determines the transmission start portion of the content data that has already been decompressed and held in the recording medium of the second data holding means 14 at this time as the second data holding means 14. From the recording medium and immediately transmit it to the receiving device.

  As described above, according to the transmission device 40, it is possible to reduce the time from the reception of the content data transmission request to the start of content data transmission. This is because the expansion of the content data transmission start portion has already been completed before the content data transmission request is received, so that the content data transmission request can be immediately responded without spending the expansion execution time of the content data transmission start portion. This is because the transmission start part of the content data can be transmitted. As a result, it is possible to shorten the time from when the user performs an operation for starting the reproduction of the content data until the actual reproduction of the content data is started. Therefore, it is possible to realize a remote reproduction system that does not cause the user to feel troublesome operation, has excellent response, and has excellent operability.

  Note that the first to fourth embodiments as described above can also be realized as a computer program. For example, the first data holding means 11, the encoding means 12, the encoding rate setting means 13, the second data holding means 14, the receiving means 15, the transmitting means 16, the history recording means 17 and the unreproduced part detecting means 18 shown in FIG. Is created using a standard computer hardware such as a CPU, main memory, input / output device, communication interface, and hard disk, and is read by the computer. As a result, the computer can function as the transmission device 2.

  In addition, the first to fourth embodiments of the remote reproduction system described above are also embodiments of the content data transmission method of the present invention. For example, step S3 in FIG. 3 is a specific example of the first encoding process, step S4 is a specific example of the data holding process, and step S6 is a specific example of the first transmission process. Step S7 is a specific example of the second encoding process, step S10 is a specific example of the second transmission process, and step S9 is a specific example of the switching process.

  Hereinafter, embodiments of the remote reproduction system of the present invention will be described with reference to the drawings. In the following embodiment of the remote reproduction system, the transmission apparatus holds content data encrypted in advance. The transmitting device decodes the content data, subsequently decodes the decrypted content data, further encodes the decoded content data at an encoding rate according to the quality of the communication environment, and further encodes the encoded content data. The content data is encrypted, and the encrypted content data is transmitted to the receiving device. The receiving device decrypts the received content data and reproduces it by streaming. Before receiving the content data transmission request transmitted from the receiving device, the transmitting device decrypts, decodes, encodes and encrypts the transmission start portion of the content data, and transmits the content data subjected to these processes. The start part is held in the transmission start part holding RAM. When the content data transmission request is received, the transmission device first transmits the transmission start portion of the content data held in the transmission start portion holding RAM.

  Now, an embodiment of the remote reproduction system of the present invention will be described more specifically with reference to FIG. As shown in FIG. 10, the remote reproduction system 100 includes a transmission device 60 and a reception device 90, and the transmission device 60 and the reception device 90 are connected to each other via a computer network 80. Encrypted content data is recorded on the hard disk built in the hard disk drive 61 of the transmission device 60. Immediately after the user turns on the transmission device 60, the data processing control unit 71 performs decryption, decoding, encoding and encryption on the transmission start portion of the encrypted content data recorded on the hard disk. Give instructions. In response to this, the decryptor 62 decrypts the transmission start portion of the encrypted content data recorded in the hard disk drive 61. Subsequently, the decoder 63 decodes the transmission start part of the decrypted content data. Subsequently, the encoder 64 encodes the transmission start portion of the decoded content data at an encoding rate according to whether the communication environment is good or bad. Subsequently, the encryptor 65 encrypts the transmission start portion of the encoded content data. The transmission start portion of the content data that has been decrypted, decoded, encoded, and encrypted is stored in the transmission start portion holding RAM 66.

  When the user presses a reproduction start button (not shown) provided on the operation unit 95 of the receiving device 90, the content data transmission request unit 96 outputs a content data transmission request. The content data transmission request is transmitted to the transmission device 60 via the network control unit 94 and the computer network 80 of the reception device 90. The network control unit 73 of the transmission device 60 receives the content data transmission request. In response to this, the transmission control unit 72 connects the transmission start part holding RAM 66 and the transmission buffer 68 via the selector 67, and transmits the transmission start part of the content data stored in the transmission start part holding RAM 66 to the transmission buffer. 68. The transmission start portion of the content data supplied to the transmission buffer 68 is immediately transmitted to the receiving device 90 via the network control unit 73 and the computer network 80. The receiving device 90 receives the transmission start portion of the content data, stores it in the receiving buffer 91, immediately decodes it by the decryptor 92, subsequently decodes it by the decoder 93, and outputs it to an output device such as a display (not shown). .

  On the other hand, immediately after the content data transmission request is received, the transmission device 60 decodes, decodes, encodes, and encrypts the other part following the content data transmission start part almost simultaneously with the transmission of the content data transmission start part. Is done. That is, under the control of the data processing unit 71, the decryptor 62, the decoder 63, the encoder 64, and the encryptor 65 decrypt, decode, encode, and encrypt other parts of the content data recorded on the hard disk. The other part of the content data subjected to these processes is directly output toward the selector 67 without passing through the transmission start part holding RAM 66. Thus, when the other part of the content data is output toward the selector 67, the transmission of the transmission start part of the content data stored in the transmission start part holding RAM 66 is completed. At this moment, the transmission control unit 72 switches the selector 67 and connects the encryptor 65 and the transmission buffer 68 directly. Thus, the other part of the content data output from the encryptor 65 is transmitted to the receiving device 90 via the transmission buffer 68, the network control unit 73, and the computer network 80 in succession to the transmission start part of the content data. . The receiving device 90 receives the other part of the content data, stores it in the receiving buffer 91, immediately decodes it by the decryptor 92, subsequently decodes it by the decoder 93, and outputs it to an output device such as a display. In receiving apparatus 90, the other part of the content data is reproduced continuously with the transmission start part of the previously received content data. That is, the content data transmission start portion and other portions are formed with continuity at the output stage of the transmission buffer 68 at the latest, and become a series of content data when received by the receiving device 90. Yes.

  On the other hand, when the user presses a reproduction stop button (not shown) of the operation unit 95 of the reception device 90, the history generation unit 97 of the reception device 90 causes the content data reproduction history information in the reception device 90 (for example, stop of the content data). Information indicating the position) is generated. The reproduction history information is transmitted to the transmission device 60 via the network control unit 94 and the computer network 80. The transmission device 60 receives the reproduction history information and records it in the history recording unit 69 on the hard disk.

  After the transmission of the content data is stopped by the user's playback stop instruction, the unplayed portion detection unit 70 of the transmission device 60 refers to the playback history information recorded in the history recording unit 69 and the playback of the content data is stopped. Recognize position. Then, the unreproduced part detection unit 70 determines that the part from the position next to the position where the reproduction of the content data has stopped to the end of the content data is an unreproduced part. Subsequently, the data processing control unit 71 decrypts, decodes and encodes the head portion of the unreproduced portion of the encrypted content data recorded on the hard disk (this portion is the transmission start portion at this point). And issues an instruction to perform encryption. In response to this, the decryptor 62, the decoder 63, the encoder 64, and the encryptor 65 decrypt, decode, encode, and encrypt the head part of the unreproduced part of the content data. The leading portion of the unreproduced portion of the content data that has been decrypted, decoded, encoded, and encrypted is stored in the transmission start portion holding RAM 66.

  When the user presses the reproduction start button provided on the operation unit 95 of the receiving device 90 again, and thereby the content data transmission request is received by the transmitting device 60, the transmission control unit 72 responds to the transmission start part. The holding RAM 66 and the transmission buffer 68 are connected via the selector 67, and the leading portion of the unreproduced portion of the content data stored in the transmission start portion holding RAM 66 is sent to the transmission buffer 68, the network control unit 73, and the computer network 80. To the receiving device 90. At substantially the same time, the transmission device 60 performs decryption, decoding, encoding, and encryption of other portions following the head portion of the unreproduced portion of the content data, and connects the encryptor 65 and the transmission buffer 68 directly. The selector 67 is switched, and the other part of the unreproduced content data is transmitted to the receiving device 90. The receiving device 90 sequentially receives the head portion of the unreproduced portion of the content data and the other portion following the sequential portion, and immediately stores and stores the received portion in the reception buffer 91, and outputs it to an output device such as a display. Output.

  As described above, according to the remote reproduction system 100, the time from when the transmission device 60 receives the content data transmission request until the transmission of the content data is started can be shortened. This is because the content data transmission start part has already been decrypted, decoded, encoded and encrypted before receiving the content data transmission request, so the content data transmission start part is decrypted, decoded and encoded. This is because the transmission start portion of the content data can be transmitted in response to the content data transmission request without spending the execution time of encryption. As a result, it is possible to shorten the time from when the user performs an operation for starting the reproduction of the content data until the actual reproduction of the content data is started. Therefore, it is possible to realize a remote reproduction system that does not cause the user to feel troublesome operation, has excellent response, and has excellent operability.

  The present invention can be changed as appropriate without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and a remote reproduction system, a transmission device, and a content data transmission method involving such a change. Computer programs are also included in the technical idea of the present invention.

The content data transmission device, content data transmission method, and remote reproduction system according to the present invention can be used for AV (Audio Visual) devices and network home appliances having a function of performing information communication by connecting to a communication network such as the Internet, for example. Furthermore, information communication is performed by connecting to a mobile communication network such as a mobile phone network, IMT-2000 (International Mobile Telecommunication 2000), PHS (Personal Handyphone System), and wireless LAN (Wireless Local Area Network). It can be used for a mobile terminal having a function. Further, the present invention can also be used for a content data transmission device or the like that is mounted on or connectable to various computer devices for consumer use or business use.

Claims (24)

A transmitting device for transmitting the content data to the receiving device in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device;
First data holding means for holding content data;
During the transmission standby period included in the period from when it becomes possible to encode the content data held by the first data holding means to when the content data transmission request is received, the first data holding means Encoding means for encoding the transmission start part of the content data held by
Second data holding means for holding a transmission start portion of the content data encoded by the encoder means;
Receiving means for receiving a content data transmission request transmitted from the receiving device;
When the content data transmission request is received by the reception unit, the transmission unit includes a transmission unit that transmits a transmission start portion of the content data held by the second data holding unit to the reception device. Transmitter device.   The transmission means includes switching means for switching from transmission of the transmission start part of the content data held by the second data holding means to transmission of another part following the transmission start part of the content data. The transmission apparatus according to claim 1, wherein the transmission apparatus is characterized in that:   2. The transmission apparatus according to claim 1, wherein the encoding unit encodes a head portion of the content data held by the first data holding unit as the transmission start portion. History recording means for recording reproduction history information indicating a history of content data transmitted from the transmitting means to the receiving apparatus and reproduced in the receiving apparatus;
An unreproduced part detecting means for detecting an unreproduced part of the content data held by the first data holding means by referring to the reproduction history information recorded by the history recording means,
The transmission apparatus according to claim 1, wherein the encoding means encodes a head part of an unreproduced part of the content data detected by the unreproduced part detection means as the transmission start part.   The transmission device according to claim 1, wherein the encoding means starts encoding the transmission start portion of the content data immediately after the transmission device is turned on.   2. The encoding unit according to claim 1, wherein the encoding unit starts encoding the transmission start portion of the content data immediately after the transmission of the content data to the receiving device is interrupted, stopped, or terminated. Transmitter device. An encoding rate setting means for setting the encoding rate of the encoding means to be changeable;
The encoding rate setting means sets the encoding rate set immediately before the content data transmission to the receiving device is interrupted, stopped, or ended as an encoding rate for encoding the content data transmission start portion. The transmission apparatus according to claim 1, wherein: A transmission apparatus and a reception apparatus connected to each other via a network, wherein the transmission apparatus transmits content data to the reception apparatus in response to a content data transmission request transmitted from the reception apparatus; A remote reproduction system for reproducing the content data by streaming,
The transmitter is
First data holding means for holding content data;
During the transmission standby period included in the period from when it becomes possible to encode the content data held by the first data holding means to when the content data transmission request is received, the first data holding means Encoding means for encoding the transmission start part of the content data held by
Second data holding means for holding a transmission start portion of the content data encoded by the encoder means;
Receiving means for receiving a content data transmission request transmitted from the receiving device;
When the content data transmission request is received by the reception unit, the transmission unit includes a transmission unit that transmits a transmission start portion of the content data held by the second data holding unit to the reception device. Remote playback system. A content data transmission method in a transmitting device for transmitting the content data to the receiving device in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device,
During the transmission waiting period included in the period from when it becomes possible to encode the content data held in the first data holding unit to when the content data transmission request is received, the first data holding unit A first encoding step for encoding a transmission start portion of the held content data;
A data holding step of holding a transmission start part of the content data encoded in the first encoding step in a second data holding unit;
Content data comprising: a first transmission step of transmitting a transmission start portion of content data held in the second data holding unit to the receiving device when the content data transmission request is received Transmission method. A second encoding step of encoding another part following the transmission start part in the content data held in the first data holding unit after the content data transmission request is received;
And a second transmission step of transmitting another portion of the content data encoded in the second encoding step to the receiving device following the transmission start portion of the content data. The content data transmission method according to item 9.   The content data according to claim 10, wherein the second transmission step includes a switching step of switching from transmission of a transmission start portion of the content data to transmission of another portion of the content data. Transmission method. A transmitting device for transmitting the content data to the receiving device in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device;
First data holding means for holding content data;
The first data holding is performed during a transmission waiting period included in a period from when it becomes possible to encrypt the content data held by the first data holding means to when the content data transmission request is received. Encryption means for encrypting the transmission start part of the content data held by the means;
Second data holding means for holding a transmission start portion of the content data encrypted by the encryption means;
Receiving means for receiving a content data transmission request transmitted from the receiving device;
When the content data transmission request is received by the reception unit, the transmission unit includes a transmission unit that transmits a transmission start portion of the content data held by the second data holding unit to the reception device. Transmitter device. A transmission apparatus and a reception apparatus connected to each other via a network, wherein the transmission apparatus transmits content data to the reception apparatus in response to a content data transmission request transmitted from the reception apparatus; A remote reproduction system for reproducing the content data by streaming,
The transmitter is
First data holding means for holding content data;
The first data holding is performed during a transmission waiting period included in a period from when it becomes possible to encrypt the content data held by the first data holding means to when the content data transmission request is received. Encryption means for encrypting the transmission start part of the content data held by the means;
Second data holding means for holding a transmission start portion of the content data encrypted by the encryption means;
Receiving means for receiving a content data transmission request transmitted from the receiving device;
When the content data transmission request is received by the reception unit, the transmission unit includes a transmission unit that transmits a transmission start portion of the content data held by the second data holding unit to the reception device. Remote playback system. A content data transmission method in a transmitting device for transmitting the content data to the receiving device in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device,
During the transmission standby period included in a period from when it becomes possible to encrypt the content data held in the first data holding unit to when the content data transmission request is received, the first data holding unit An encryption process for encrypting the transmission start part of the content data held in
A data holding step of holding a transmission start portion of the content data encrypted in the encryption step in a second data holding unit;
A content data transmission method comprising: a transmission step of transmitting a content data transmission start portion held in the second data holding unit to the receiving device when the content data transmission request is received. . A transmitting device for transmitting the content data to the receiving device in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device;
First data holding means for holding encrypted content data;
During a transmission standby period included in a period from when it becomes possible to decrypt the encrypted content data held by the first data holding unit to when the content data transmission request is received, Decryption means for decrypting the transmission start portion of the encrypted content data held by the first data holding means;
Second data holding means for holding a transmission start portion of the content data decrypted by the decrypting means;
Receiving means for receiving a content data transmission request transmitted from the receiving device;
When the content data transmission request is received by the reception unit, the transmission unit includes a transmission unit that transmits a transmission start portion of the content data held by the second data holding unit to the reception device. Transmitter device. A transmission apparatus and a reception apparatus connected to each other via a network, wherein the transmission apparatus transmits content data to the reception apparatus in response to a content data transmission request transmitted from the reception apparatus; A remote reproduction system for reproducing the content data by streaming,
The transmitter is
First data holding means for holding encrypted content data;
During a transmission standby period included in a period from when it becomes possible to decrypt the encrypted content data held by the first data holding unit to when the content data transmission request is received, Decryption means for decrypting the transmission start portion of the encrypted content data held by the first data holding means;
Second data holding means for holding a transmission start portion of the content data decrypted by the decrypting means;
Receiving means for receiving a content data transmission request transmitted from the receiving device;
When the content data transmission request is received by the reception unit, the transmission unit includes a transmission unit that transmits a transmission start portion of the content data held by the second data holding unit to the reception device. Remote playback system. A content data transmission method in a transmitting device for transmitting the content data to the receiving device in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device,
During the transmission standby period included in a period from when it becomes possible to decrypt the encrypted content data held in the first data holding unit to when the content data transmission request is received, A decryption step of decrypting a transmission start part of encrypted content data held in one data holding unit;
A data holding step of holding a transmission start part of the content data decrypted in the decrypting step in a second data holding unit;
A content data transmission method comprising: a transmission step of transmitting a content data transmission start portion held in the second data holding unit to the receiving device when the content data transmission request is received. . A transmitting device for transmitting the content data to the receiving device in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device;
First data holding means for holding compressed content data;
During the transmission waiting period included in the period from the time when the compressed content data held by the first data holding means can be decompressed to the time when the content data transmission request is received, Decompression means for decompressing the transmission start portion of the compressed content data held by the data holding means;
Second data holding means for holding a transmission start portion of the content data expanded by the expansion means;
Receiving means for receiving a content data transmission request transmitted from the receiving device;
When the content data transmission request is received by the reception unit, the transmission unit includes a transmission unit that transmits a transmission start portion of the content data held by the second data holding unit to the reception device. Transmitter device. A transmission apparatus and a reception apparatus connected to each other via a network, wherein the transmission apparatus transmits content data to the reception apparatus in response to a content data transmission request transmitted from the reception apparatus; A remote reproduction system for reproducing the content data by streaming,
The transmitter is
First data holding means for holding compressed content data;
During the transmission waiting period included in the period from the time when the compressed content data held by the first data holding means can be decompressed to the time when the content data transmission request is received, Decompression means for decompressing the transmission start portion of the compressed content data held by the data holding means;
Second data holding means for holding a transmission start portion of the content data expanded by the expansion means;
Receiving means for receiving a content data transmission request transmitted from the receiving device;
When the content data transmission request is received by the reception unit, the transmission unit includes a transmission unit that transmits a transmission start portion of the content data held by the second data holding unit to the reception device. Remote playback system. A content data transmission method in a transmitting device for transmitting the content data to the receiving device in response to a content data transmission request transmitted from the receiving device in order to reproduce the content data by streaming in the receiving device,
During the transmission waiting period included in a period from when it becomes possible to expand the compressed content data held in the first data holding unit to when the content data transmission request is received, the first data A decompression step of decompressing a transmission start portion of the compressed content data held in the holding unit;
A data holding step of holding a transmission start part of the content data expanded in the expansion step in a second data holding unit;
A content data transmission method comprising: a transmission step of transmitting a content data transmission start portion held in the second data holding unit to the receiving device when the content data transmission request is received. .   A computer program for causing a computer to function as the transmission device according to claim 1.   A computer program for causing a computer to function as the transmission device according to claim 12.   A computer program for causing a computer to function as the transmission device according to claim 15. A computer program for causing a computer to function as the transmission device according to claim 18.

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