JP2007028212A - Reproducing device and reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for allowing a user to execute special reproduction of multimedia data such as MPEG data by preventing unnatural interruptions of voice and breakdowns of a decoder of a display device while suppressing costs and power consumption. <P>SOLUTION: A stream change-over switch 111 is provided to a data transmitting/reproducing device 140. When the special reproduction of the MPEG data is executed, a mute audio ES generated as an audio ES by a mute generator 110 is used or the audio ES is not multiplexed to a TS. Though a simple video encoder 106 re-encodes the decoded video ES, it has a simple constitution for encoding only as an intraframe encoded image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data reproduction / transmission apparatus and a data reproduction / transmission method for reproducing and transmitting multimedia data including video data and audio data.

  Conventionally, moving image data and audio data encoded by an encoding method such as MPEG are reproduced from a recording medium, transmitted in an encoded state to an external display device, etc., and decoded and displayed. Technology is known. As described above, IEEE 1394 (Institute of Electrical and Electronics Engineers 1394) is often used as a digital interface for transmitting and receiving encoded moving image data and the like.

  As described above, when special reproduction such as slow, still, and frame advance is realized in a system in which MPEG data is transmitted to a display device and decoded and displayed, it can be realized as follows. For example, this can be realized by adding specific additional information indicating special reproduction to MPEG data and transmitting it, and decoding in accordance with this additional information in a decoder.

  Specifically, information related to special playback is described in the DSM_trick_mode field in the header information of a PES (Packetized Elementary Stream) packet.

  However, there are many decoders that cannot perform the decoding process according to DSM_trick_mode of the header information of the PES packet, which is such additional information for special reproduction. Therefore, a data reproduction / transmission apparatus that enables special reproduction of MPEG data even in such a display apparatus has been proposed.

For example, in Patent Document 1, all MPEG data reproduced from a recording medium is once decoded, then re-encoded and transmitted.
JP 2001-28748 A

  However, in Patent Document 1, it is necessary to provide a complete encoder (encoder) in the reproduction transmission apparatus. The “perfect encoder” is an encoder capable of generating all pictures of an intra-frame encoded image (I picture), an inter-frame predictive encoded image (P picture), and a bidirectional predictive encoded image (B picture). It means that. In such an encoder, for example, a frame memory for predictive encoding is required, and thus there is a problem that the circuit configuration becomes complicated and the cost and power consumption increase.

  Further, in Patent Document 1, since the image is updated only in the frame of the I picture of the MPEG data, there is a problem that the followability of the image is deteriorated during special reproduction. Therefore, for example, at the time of slow reproduction, the image update frequency becomes low, and slow reproduction cannot be performed smoothly.

  Further, in Patent Document 1, there is no clear provision regarding a decoding operation or the like when the display device receives dummy packet information or DIT information, and the behavior can be different for each display device, so that the display device can appropriately perform special reproduction. There is no guarantee. The DIT information is information indicating discontinuity of the encoded bit stream (data stream) and is an abbreviation for Discontinuity Information Table.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a technique capable of realizing special reproduction even when a decoder having no special decoding function is used.

  In order to solve the above-described problems, a playback apparatus according to the present invention plays back a coded data sequence including moving image data encoded using intraframe coding and interframe prediction coding from a recording medium. Decoding means for decoding the moving picture data reproduced by the reproducing means, and encoding for outputting encoded moving picture data obtained by encoding the moving picture data decoded by the decoding means only by the intra-frame coding And the moving image data reproduced by the reproducing unit or the encoded moving image data output from the encoding unit, and the selected moving image data is encoded and transmitted to the external device. Transmitting means for transmitting, normal playback mode in which the moving image data is reproduced at a normal reproduction speed, and the transmitting means transmits moving image data reproduced by the reproducing means; and The image data reproduced at a speed different from the normal reproduction speed, the transmission unit is characterized in that it comprises a mode switching means for switching between a special playback mode for transmitting the moving image data output from said coding means.

  In addition, another playback apparatus of the present invention includes a playback means for playing back a coded data sequence including moving image data encoded using intra-frame coding and inter-frame prediction coding from a recording medium, and the playback A decoding means for decoding the moving image data reproduced by the means, and a code comprising the picture data decoded by the decoding means and the copy picture data for decoding the same data as the intra-frame encoded data and the reference frame Selected from the encoding means for converting into encoded moving image data and outputting; and the moving image data reproduced by the reproducing means or the encoded moving image data output from the encoding means; Transmitting means for transmitting image data in an encoded form to an external device; and reproducing the moving image data at a normal reproduction speed, wherein the transmitting means reproduces the reproduction means. Normal reproduction mode for transmitting the moving image data, and special reproduction mode for reproducing the moving image data at a speed different from the normal reproduction speed, and for transmitting the moving image data output from the encoding means by the transmitting means And a mode switching means for switching between.

  Other features of the present invention will become more apparent from the accompanying drawings and the following description of the best mode for carrying out the invention.

  With the above configuration, according to the present invention, special reproduction can be realized even when a decoder having no special function is used while suppressing cost and power consumption.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  In the following embodiments, MPEG data will be described as an example of multimedia data including video data and audio data. However, the present invention can be applied to other types of multimedia data.

  In addition, as an example of special reproduction, slow reproduction, still reproduction, and frame advance reproduction will be described, but the present invention can be applied to other special reproduction (for example, fast forward reproduction and rewind reproduction).

[First Embodiment]
<Device configuration>
FIG. 1 is a functional block diagram showing a configuration of a data transmission / reproduction device 140 to which the present invention can be applied and a display device 141 as an external device. The data transmission / reproduction device 140 and the display device 141 are connected by an IEEE 1394 cable 117, and MPEG data is transmitted from the data transmission / reproduction device 140 to the display device 141 as a transport stream (hereinafter referred to as “TS”).

  First, the configuration of the data transmission / reproduction device 140 will be described.

  The storage medium 100 is for storing MPEG data to be transmitted, and may be any type of medium such as an HDD (hard disk), a DVD, or a flash memory.

  The buffer memory 101 is a memory for temporarily storing MPEG data acquired from the storage medium 100.

  The DEMUX 102 converts an image (video) data and audio (audio) data included in MPEG data acquired from the storage medium 100 into an elementary stream (hereinafter referred to as “ES”) when multiplexed. belongs to. “DEMUX” means a demultiplexer. The multiplexed MPEG data is converted into video ES and audio ES.

  The video ES memory 103 is a memory for temporarily storing the video ES obtained by the DEMUX 102.

  The video decoder 104 is a decoder that decodes the video ES into a data format that can be displayed on the monitor 105.

  The simple video encoder 106 is an encoder for re-encoding the video data decoded by the video decoder 104. Unlike the normal video encoder of the MPEG standard, the simple video encoder 106 can generate only I pictures. Therefore, a frame memory or the like for predictive coding is unnecessary and can be simplified.

  The audio ES memory 107 is a memory for temporarily storing the audio ES obtained by the DEMUX 102.

  The audio decoder 108 is a decoder that decodes the audio ES into a data format that can be output by the speaker 109.

  The mute generator 110 is for outputting a silent audio ES (hereinafter referred to as “mute audio ES”).

  The stream changeover switch 111 is for switching the TS to be output (transmitted) between normal reproduction and special reproduction.

  The TS_MUX 112 is for generating a TS by multiplexing the video ES and the audio ES. “MUX” means a multiplexer.

  The external I / F 113 is an IEEE 1394 interface.

  The CPU 114 is for controlling the overall operation of the data transmission / reproduction device 140, and functions by executing a program (firmware) stored in the ROM 115.

  The ROM 115 is a nonvolatile memory for storing a program executed by the CPU 114.

  The RAM 116 is a volatile memory that is used as a work area when the CPU 114 executes a program stored in the ROM 115.

  In addition, the data transmission / reproduction device 140 includes an operation unit (not shown), and the user can give an instruction to the data transmission / reproduction device 140 via the operation unit.

  Next, the configuration of the display device 141 will be described.

  The external I / F 118 is an IEEE1394 interface.

  The TS_DEMUX 119 is a demultiplexer that converts the TS transmitted from the data transmission / reproduction device 140 into a video ES and an audio ES.

  The video decoder 120 is a decoder that decodes the video ES converted by the TS_DEMUX 119 into a data format that can be displayed on the monitor 121.

  The audio decoder 122 is a decoder that decodes the audio ES converted by the TS_DEMUX 119 into a data format that can be output by the speaker 123.

  The CPU 124 is for controlling the operation of the entire display device 141, and functions by executing a program (firmware) stored in the ROM 125.

  The ROM 125 is a nonvolatile memory for storing a program executed by the CPU 124.

  The RAM 126 is a volatile memory used as a work area when the CPU 124 executes a program stored in the ROM 125.

  In addition, the display device 141 includes an operation unit (not shown), and the user can give an instruction to the display device 141 via the operation unit.

<TS during normal playback and special playback>
FIG. 2 is a diagram schematically showing TS at the time of normal reproduction and special reproduction of MPEG data, images output to the monitor 105, and the like. Hereinafter, with reference to FIG. 2 and FIGS. 3 to 6, the operation of the data transmission / reproduction device 140 during normal reproduction, the operation of the display device 141, the operation of the data transmission / reproduction device 140 during special reproduction, and the normal reproduction from the special reproduction. The operation of the data transmission / reproduction device 140 when switching to will be described.

<Operation of Data Transmission / Reproduction Device 140 at Normal Reproduction>
FIG. 3 is a flowchart showing the flow of data transmission processing of the data transmission / reproduction device 140 during normal reproduction of MPEG data. When the data transmission / reproduction device 140 receives an instruction for normal reproduction of MPEG data, the processing of this flowchart starts. The data transmission / reproduction device 140 can receive a normal reproduction instruction via an operation unit (not shown) of the data transmission / reproduction device 140, the IEEE 1394 cable 117, or the like.

  During normal playback, the video side (left) of the stream selector switch 111 in FIG. 1 is connected to “a”, and the audio side (right) is connected to “c”.

  In step S <b> 301, the CPU 114 in FIG. 1 reads MPEG data stored in the storage medium 100 and stores it in the buffer memory 101. The format of the temporarily stored MPEG data may be TS, PS (program stream), or ES in which video data and audio data are not multiplexed.

  In step S302, the CPU 114 determines whether the multiplexed MPEG data stored in the buffer memory 101 is a TS or PS in which video data and audio data are multiplexed. If it is multiplexed, the process proceeds to step S303, and if not multiplexed, the process proceeds to step S304.

  In step S303, the DEMUX 102 converts the MPEG data stored in the buffer memory 101 into a video ES and an audio ES.

  In step S <b> 304, the CPU 114 stores the video ES and audio ES stored in the buffer memory 101 in the video ES memory 103 and audio ES memory 107.

  In step S <b> 305, the video decoder 104 decodes the video ES stored in the video ES memory 103 and outputs the decoded video ES to the monitor 105. Also, the audio decoder 108 decodes the audio ES stored in the audio ES memory 107 and outputs it to the speaker 109. An example of a video frame (picture) and audio output here is shown in the upper part of FIG.

  In step S306, the TS_MUX 112 multiplexes the video ES and audio ES stored in the video ES memory 103 and the audio ES memory 107 to generate a TS. Since the stream format on IEEE1394 is TS, MPEG data can be transmitted to the display device 141.

  In step S307, the external I / F 113 transmits the TS generated in step S306 to the display device 141 via the IEEE 1394 cable 117. An example of TS to be transmitted is the middle part of FIG.

  In step S308, the CPU 114 determines whether or not the reproduction of MPEG data has been completed. The end of reproduction occurs, for example, when the data transmission / reproduction device 140 transmits MPEG data being transmitted to the end, or when a reproduction end instruction is received from an operation unit (not shown) or the like. When the reproduction is finished, the process of this flowchart is finished. If reproduction has not ended, the process returns to step S301, and the above-described processing is repeated.

<Operation of Display Device 141>
FIG. 4 is a flowchart showing a flow of data reproduction processing of the display device 141 that is common during normal reproduction and special reproduction of MPEG data. The processing at the time of normal playback and special playback is common because the data transmission and playback device 140 transmits different TSs according to the type of playback, but the packet format is the same for both playbacks. When the external I / F 118 detects that a TS has been sent via the IEEE 1394 cable 117, the processing of this flowchart starts.

  In step S401, the external I / F 118 receives the TS via the IEEE 1394 cable 117.

  In step S402, TS_DEMUX 119 converts TS into video ES and audio ES.

  In step S <b> 403, the video decoder 120 decodes the video ES and outputs it to the monitor 121. Also, the audio decoder 122 decodes the audio ES and outputs it to the speaker 123. An example of a video frame (picture) and audio output here in the case of normal reproduction is shown in the lower part of FIG. An example of a video frame (picture) and audio output in the case of special reproduction is shown in the lower part of FIG. 2B, and details will be described later.

<Operation of Data Transmission / Reproduction Device 140 at Special Reproduction>
FIG. 5 is a flowchart showing the flow of data transmission processing of the data transmission / reproduction device 140 during special reproduction of MPEG data. Steps for performing the same processing as in normal reproduction in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted. When the data transmission / reproduction device 140 receives an instruction for special reproduction of MPEG data or receives an instruction to change to special reproduction during normal reproduction, the processing of this flowchart starts.

  In the present embodiment, it is assumed that an instruction to change to still playback is received during normal playback. Here, it is assumed that the data transmission / reproduction device 140 receives a still reproduction instruction at the beginning timing of the section where “freeze image” is displayed in the upper part of FIG.

  In step S501, the CPU 114 in FIG. 1 connects the video side (left) of the stream changeover switch 111 to “b” and the audio side (right) to “d”. Further, the CPU 114 issues DIT information indicating the discontinuity of the stream from the external I / F 118 and notifies the display device 141 that the stream is divided. Further, the CPU 114 acquires the bit rate of the video ES before decoding from the video ES memory 103 and notifies the video simple encoder 106 of the bit rate. Further, the CPU 114 acquires the audio ES bit rate, sampling frequency, and encoding mode such as MPEG1 audio and AC3 from the audio ES memory 107 and notifies the mute generator 110 of them.

  In step S <b> 502, the CPU 114 acquires (reads) MPEG data stored in the storage medium 100 and stores it in the buffer memory 101. However, unlike the step S301, the reading here differs in the interval of image frames read from the MPEG data according to the type of special reproduction. For example, in the case of still playback, the video frame does not advance to the next frame, so that a new image frame is not read during still playback. In the case of slow reproduction, all MPEG data is sequentially read from the storage medium 100, but is read in units of a predetermined encoding unit (GOP), and the reading interval is in accordance with the reproduction speed. For fast-forward playback, image frames are read every predetermined number of frames. Therefore, as described above, the case of still reproduction will be described in the present embodiment, but the same can be said for other types of special reproduction by adjusting the interval between image frames to be read.

  In step S503, the video simple encoder 106 re-encodes each frame of the video signal decoded by the video decoder 104 as a video ES including only I pictures. The re-encoding here may be performed a plurality of times for the same image frame depending on the reproduction mode. For example, in the case of still reproduction, the video simple encoder 106 continues to re-encode a specific image frame until it is released. For example, in the case of 1/3 times slow reproduction, the video simple encoder 106 re-encodes each image frame three times to adjust the reproduction speed. The re-encoding algorithm is the same as normal MPEG encoding, and variable-length encoding is performed by combining DCT (discrete cosine transform), quantization, zigzag scanning, and the like. Note that the simple video encoder 106 determines a quantization step and the like with the goal that the re-encoded video ES is equal to or lower than the bit rate notified in step S501.

  In step S503, the mute generator 110 also generates a mute audio ES that matches the format notified in step S501. The mute audio ES is obtained by sampling silence at a predetermined sampling frequency and encoding it in a predetermined format. Therefore, if the sampling frequency is indefinite, it is generated in real time, but if the sampling frequency is fixed and can be specified in advance, the mute audio ES becomes fixed data. Therefore, the data prepared in advance in the ROM 115 or the like is used. Also good.

  In step S504, the TS_MUX 112 multiplexes the video ES generated by the video simple encoder 106 and the mute audio ES generated by the mute generator 110 to generate a TS.

  An example of TS transmitted at the time of still reproduction is an I picture that continues for 4 frames from the “DIT” display on the left side in the middle of FIG. 2B and mute data corresponding thereto. As described above, an example of a video frame (picture) and audio output to the display device 141 is shown in the lower part of FIG. 2B, and the left “DIT” display in the middle part of FIG. 2B. This is a portion corresponding to an I picture that lasts for 4 frames from.

<Operation of Data Transmission / Reproducing Device 140 when Switching from Special Playback to Normal Playback>
FIG. 6 is a flowchart showing the flow of data transmission processing of the data transmission / reproduction device 140 when the MPEG data reproduction method is switched from special reproduction to normal reproduction. Steps for performing the same processing as in normal reproduction in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted. When the data transmission / reproduction device 140 receives an instruction to change to normal reproduction during special reproduction of MPEG data, the processing of this flowchart starts.

  In step S601, the CPU 114 in FIG. 1 connects the audio side (right) of the stream selector switch 111 to “c”. As a result, the audio ES is switched from that generated by the mute generator 110 to that included in the MPEG data stored in the storage medium 100. On the other hand, the video side (left) of the stream selector switch 111 is not switched. This is because the video decoder 120 of the display device 141 uses the I picture by the simple video encoder 106 until the I picture enters the video ES memory 103 because it can be decoded only by the video ES starting from the I picture. .

  In step S602, the CPU 114 determines whether a picture obtained from the video ES stored in the video ES memory 103 is an I picture. If it is an I picture, the process proceeds to step S605, and if it is not an I picture, the process proceeds to step S603.

  In step S603, similar to step S503 in FIG. 5, the video simple encoder 106 re-encodes each frame of the video signal decoded by the video decoder 104 as a video ES including only I pictures. However, unlike step S503, the mute generator 110 does not generate the mute audio ES.

  In step S604, the TS_MUX 112 multiplexes the video ES generated by the video simple encoder 106 and the audio ES stored in the audio ES memory 107 to generate a TS.

  In step S602, if the picture obtained from the video ES stored in the video ES memory 103 is an I picture, the process proceeds to step S605 as described above.

  In step S605, the CPU 114 connects the video side (left) of the stream selector switch 111 to “a”. Further, the CPU 114 issues DIT information indicating the discontinuity of the stream from the external I / F 118 and notifies the display device 141 that the stream is divided. Next, the process returns to the normal reproduction process (FIG. 3).

  FIG. 2B shows the output and TS of the monitor 105 and the like when the data transmission / reproduction device 140 is switched from special reproduction to normal reproduction. A portion corresponding in time to three I pictures lined up to the left from the “DIT” display on the right side in the middle of FIG. 2B corresponds to the processing of this flowchart.

  In this embodiment, the type of special reproduction is still reproduction, but as described with reference to FIG. 5, the flowchart of FIG. 6 can be applied to other types of special reproduction (for example, slow reproduction and frame advance reproduction). The CPU 114 connects the audio side (right) of the stream selector switch 111 to “c” simultaneously with the change to normal playback. Further, when the picture obtained from the video ES stored in the video ES memory 103 becomes an I picture, the video side (left) is connected to “a”. This is because there is no difference depending on the type of special reproduction.

<Summary of First Embodiment>
As described above, according to this embodiment, in the special transmission of MPEG data, the data transmission / reproduction device 140 re-encodes the video ES into a video ES composed of only I pictures. Further, the mute generator 110 generates a mute audio ES. The TS_MUX 112 multiplexes the video ES by the video simple encoder 106 and the mute audio ES by the mute generator 110 to generate a TS.

  When the MPEG data playback method is switched from special playback to normal playback, the audio ES is immediately switched from that generated by the mute generator 110 to that based on MPEG data stored in the storage medium 100. However, until the picture obtained from the video ES stored in the video ES memory 103 by the CPU 114 becomes an I picture, the video ES continues to use the video ES generated by the video simple encoder 106.

  As a result, since the mute audio ES is used during special reproduction, the sound is silent and no unnatural interruption of sound occurs. Further, when the video simple encoder 106 generates a video ES including only I pictures, it is not necessary to invalidate the data indicating the storage amount of the virtual input buffer of the decoder, so that the decoder of the display device 141 fails. Can be prevented. Furthermore, since the video simple encoder 106 does not perform inter-frame prediction, the video simple encoder 106 can have a simple configuration, and cost and power consumption can be reduced.

[Second Embodiment]
In the first embodiment, during the special reproduction of MPEG data, the video simple encoder 106 of FIG. 1 generates a video ES consisting of only I pictures. In the second embodiment, a mode will be described in which the video simple encoder 106 generates a video ES including a copy picture in addition to an I picture at the time of special reproduction of MPEG data. The copy picture is a kind of P picture and represents the same image as the image represented by the immediately preceding picture.

  In the present embodiment, the configurations of the data transmission / reproduction device 140 and the display device 141 may be the same as those in the first embodiment (FIG. 1), and the description thereof is omitted. The flow of data transmission processing of the data transmission / reproduction device 140 during normal reproduction of MPEG data and the flow of reproduction processing of MPEG data by the display device 141 are also the same as in the first embodiment (FIGS. 3 and 4). Therefore, explanation is omitted.

<Composition of copy picture>
FIG. 7 is a diagram illustrating a configuration of a copy picture. Each block in FIG. 7 represents a macro block (MB). Since the copy picture represents the same image as the image represented by the immediately preceding picture, most of the MB is composed of skipped macroblocks (SMB). However, since MB at both ends of the slice cannot use SMB according to the MPEG specification, MB (MBH) with macroblock_type set to MC and NotCoded is used. MBH is MB that has MB address information and a motion vector of (0, 0) and does not have a DCT coefficient.

  Since the copy picture is mostly fixed data, it is stored in advance in the ROM 115 in FIG. 1 or the like, and the video simple encoder 106 uses this to generate a video ES during special reproduction of MPEG data. Also good. Alternatively, the CPU 114 may analyze the sequence header of the video ES to check the size of the picture, and the video simple encoder 106 may generate a copy picture accordingly. As described above, the video simple encoder 106 does not include a frame memory and cannot generate a P picture in principle. However, since a copy picture does not perform motion compensation, the video simple encoder 106 can generate it.

  Note that the copy picture may be configured not in the P picture format but in the B picture format. Even in this case, the copy picture, which is a kind of B picture, represents the same image as the image represented by the immediately preceding picture.

  Since the copy picture has a smaller data amount than the I picture, unlike the first embodiment in which the video ES is generated using only the I picture, a large amount of code can be obtained without increasing the data transmission bit rate. Can be assigned. Therefore, the image quality can be improved when special reproduction of MPEG data is performed.

<TS during normal playback and special playback>
FIG. 8 is a diagram schematically showing a TS during normal reproduction and special reproduction of MPEG data, an image output to the monitor 105, and the like. The operation of the data transmission / reproduction device 140 during special reproduction and the operation of the data transmission / reproduction device 140 when switching from special reproduction to normal reproduction will be described below with reference to FIGS. 8 and 9 to 12.

<Operation of Data Transmission / Reproduction Device 140 at Special Reproduction>
FIG. 9 is a flowchart showing the flow of data transmission processing of the data transmission / reproduction device 140 during special reproduction of MPEG data. Steps that perform the same processing as in the first embodiment (FIG. 5) are assigned the same reference numerals, and descriptions thereof are omitted. When the data transmission / reproduction device 140 receives an instruction for special reproduction of MPEG data or receives an instruction to change to special reproduction during normal reproduction, the processing of this flowchart starts.

  In this embodiment, as in the first embodiment, it is assumed that an instruction to change to still playback is received during normal playback. The data transmission / reproduction device 140 receives a still reproduction instruction at the beginning timing of the section where “freeze image” is displayed in the upper part of FIG.

  In step S901, the CPU 114 in FIG. 1 performs processing similar to the initialization setting performed in step S501, and in addition, initializes the variable m to a constant n. The constant n is a value indicating how many I-pictures appear in the video ES composed of I-pictures and copy pictures. Since the value of the constant n determines the update frequency of the image output by the monitor 121 or the like during special reproduction of MPEG data, the CPU 114 determines the value of the constant n according to the type of special reproduction. The relationship between the value of the constant n and the type of special reproduction will be described later with reference to FIGS.

  In step S902, the CPU 114 determines whether m <n. If m <n, since the next picture is an I picture, the process proceeds to step S903. If m <n, since the next picture is a copy picture, the process advances to step S904.

  In step S903, the video simple encoder 106 re-encodes one picture decoded by the video decoder 104 as an I picture. Further, the mute generator 110 generates a mute audio ES. Further, the variable m is set to 0.

  In step S904, the video simple encoder 106 generates a copy picture or acquires a copy picture stored in advance in the ROM 115. Further, the mute generator 110 generates a mute audio ES. Further, 1 is added to the variable m.

Similar to the first embodiment, the video ES including the pictures generated in steps S903 and S904 is generated with the goal that the video simple encoder 106 is equal to or lower than the bit rate notified in step S901. Here, since the data amount of the copy picture is constant, the video simple encoder 106

(((Data amount of I picture) + (data amount of copy picture) × (n−1)) / n)
X (frame rate) = (target bit rate)

The quantization step and the like are determined so that the I picture is generated.

  An example of TS transmitted at the time of still playback is shown in the middle of FIG. 8B, the “I, C, C, I” picture that continues four frames from the “DIT” display on the left side, and the corresponding mute. It is data.

  Similarly to the first embodiment, the process of the flowchart in FIG. 9 can also be applied to special playback other than still playback.

<Determination of constant n>
As described above, the value of the constant n determines the update frequency of the image output by the monitor 121 or the like during special reproduction of MPEG data, so the CPU 114 determines the value of the constant n according to the type of special reproduction.

  When the special reproduction type is still reproduction, the output image does not need to be updated, so the CPU 114 determines a large constant n. This value may be practically infinite. For example, when n = 0, the data transmission / reproduction device 140 may be configured so that the constant n is regarded as infinite.

  When the type of special reproduction is slow reproduction, the CPU 114 determines a constant n based on how many times the slow reproduction, in other words, how many frames the same image is continuously output. FIG. 10 is a diagram schematically showing a TS when n = 3 and n = 2 and an image output to the monitor 105 or the like in the slow reproduction at 1/3 speed.

  At this time, two freeze images (the same image as the immediately preceding image) are continuously output for each updated image to the monitor 105 of the data transmission / reproduction device 140. Therefore, as shown in the upper part of FIG. 10, when n = 3, the image output to the monitor 121 of the display device 141 is updated at the most appropriate frequency. In other words, when the value of the constant n is determined so as to coincide with the image update period in the slow reproduction, the followability of the image output to the monitor 121 of the display device 141 becomes the best.

  When the type of special playback is frame advance playback, the number of freeze images following one updated image is not constant. Therefore, as shown in FIG. 11, when a value obtained by adding 1 to the minimum number of frozen images in frame-by-frame playback or a natural number less than that is a constant n, the followability of the image output to the monitor 121 of the display device 141 Will improve.

  Note that in the playback mode in which the image frames included in the MPEG data are displayed every predetermined number of frames as in the case of the special playback type fast-forward playback, the video simple encoder 106 uses a copy picture with n = 1. do not do. Further, as in the first embodiment, the CPU 114 acquires (reads out) MPEG data stored in the storage medium 100 every predetermined number of frames.

<Operation of Data Transmission / Reproducing Device 140 when Switching from Special Playback to Normal Playback>
FIG. 12 is a flowchart showing the flow of data transmission processing of the data transmission / reproduction device 140 when the MPEG data reproduction method is switched from special reproduction to normal reproduction. Steps that perform the same processing as in the first embodiment (FIG. 6) are assigned the same reference numerals, and descriptions thereof are omitted. When the data transmission / reproduction device 140 receives an instruction to change to normal reproduction during special reproduction of MPEG data, the processing of this flowchart starts.

  In step S1201, the CPU 114 determines whether m <n as in step S902. Here, the values of the variable m and the constant n are the same as the values at the time of special reproduction before the data transmission / reproduction device 140 receives an instruction to change to normal reproduction. If m <n, since the next picture is an I picture, the process advances to step S1202. If m <n, since the next picture is a copy picture, the process advances to step S1203.

  In step S1202, the video simple encoder 106 re-encodes one picture decoded by the video decoder 104 as an I picture, as in step S903. Also, the variable m is set to 0. However, unlike step S903, the mute generator 110 does not generate the mute audio ES.

  In step S1203, the video simplified encoder 106 generates a copy picture, or acquires a copy picture stored in advance in the ROM 115, as in step S904. Also, 1 is added to the variable m. However, unlike step S904, the mute generator 110 does not generate the mute audio ES.

  FIG. 8B shows the output and TS of the monitor 105 and the like when the data transmission / reproduction device 140 is switched from special reproduction to normal reproduction. The portion corresponding temporally to the three “C, C, I” pictures arranged on the left of the “DIT” display on the right side of the middle stage in FIG. 8B corresponds to the processing of this flowchart.

  As described above, when the data transmission / reproduction device 140 receives an instruction to change to the normal reproduction during the special reproduction, the audio transmission immediately returns to the normal reproduction. However, the reproduction of the video continues the special reproduction until the picture obtained from the video ES stored in the video ES memory 103 becomes an I picture.

  In the present embodiment, the type of special playback is still playback. However, as in the first embodiment, the flowchart of FIG. 12 can also be applied to other types of special playback (for example, slow playback and frame feed playback). The CPU 114 connects the audio side (right) of the stream selector switch 111 to “c” simultaneously with the change to normal playback. Further, when the picture obtained from the video ES stored in the video ES memory 103 becomes an I picture, the video side (left) is connected to “a”. This is because there is no difference depending on the type of special reproduction.

<Summary of Second Embodiment>
As described above, according to the present embodiment, at the time of special reproduction of MPEG data, the data transmission / reproduction device 140 generates a video ES including a copy picture in addition to an I picture.

  Thereby, the image quality can be improved when the display device 141 performs special reproduction of the MPEG data. This is because a copy picture has a smaller amount of data than an I picture, so that a larger amount of code can be assigned to an I picture without increasing the bit rate of the TS to be transmitted.

[Other Embodiments]
<Discard audio ES during special playback>
In each of the above-described embodiments, during special playback of MPEG data, the mute generator 110 generates the mute audio ES, and the TS_MUX 112 multiplexes this with the video ES to generate the TS. Prevented.

  However, the same effect can be obtained by discarding the audio ES included in the MPEG data without using the mute audio ES.

  FIG. 13 is a diagram schematically showing a TS and an image output to the monitor 105 or the like when the audio ES is discarded during special reproduction of MPEG data. As shown in the middle part of FIG. 13B, the audio ES is discarded while the video ES is being re-encoded. Unlike the first and second embodiments, even when the data transmission / reproduction device 140 receives an instruction to change to normal reproduction, until the picture obtained from the video ES stored in the video ES memory 103 becomes an I picture. The audio ES is discarded. This is because it is not preferable to change the stream multiplexed by the TS_MUX 112 until the “DIT” is issued, because the stream is divided by discarding the audio ES.

<Conversion of interlaced format to progressive format>
In each embodiment described above, when the video data included in the MPEG data recorded on the storage medium 100 is in the interlace format, it may be converted into the progressive format when special reproduction is performed. In this case, the simple video encoder 106 converts the interlaced video data decoded by the video decoder 104 into a progressive format and then re-encodes it to generate a video ES.

  If the interlace format is converted to the progressive format, the image quality during special reproduction of MPEG data can be improved. This is because, in the case of the interlaced format, when the same frame is continuously displayed on the monitor 121, fields that are temporally changed are alternately displayed, and flickering occurs. On the other hand, in the case of the progressive format, since each frame is composed of image data at a single time, flicker does not occur even if the same frame is continuously displayed on the monitor 121.

  The CPU 114 can determine whether the video data is in the interlace format or the progressive format by referring to the Progressive Frame (PF) that is the header information of the video ES. If PF = 1, the video data is in progressive format, and if PF = 0, it is in interlace format.

  Conversion of video data from interlaced format to progressive format can be performed using any known technique. Here, a method for determining a reference field at the time of conversion will be described.

  The reference field at the time of conversion uses the final field at the time of normal reproduction of MPEG data. FIG. 14 is a diagram showing a table used when determining the final field during normal reproduction of MPEG data.

  When Repeat First Field (RF) is 0, the frame is composed of two fields. Therefore, the reverse value of Top Field First (TF) is the final field. That is, if TF = 1 (Top Field First), Bottom Field is the last field. When TF = 0 (Bottom Field First), Top Filed is the last field.

  Conversely, when RF is 1, Top Field is the final field when TF = 1, and Bottom Filed is the final field when TF = 0.

<Others>
The processing of each embodiment described above may provide a system or apparatus with a storage medium storing software program codes embodying each function. The functions of the above-described embodiments can be realized by the computer (or CPU or MPU) of the system or apparatus reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying such a program code, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, or the like can be used. Alternatively, a CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like can be used.

  The functions of the above-described embodiments are not only realized by executing the program code read by the computer. In some cases, an OS (operating system) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. include.

  Further, the program code read from the storage medium may be written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. After that, the CPU of the function expansion board or function expansion unit performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

It is a functional block diagram which shows the structure of the data transmission reproduction | regeneration apparatus 140 which can apply this invention, and the display apparatus 141 as an external apparatus. It is a figure which shows typically the image etc. output to TS at the time of normal reproduction | regeneration of MPEG data and special reproduction | regeneration, the monitor 105 grade | etc.,. It is a flowchart which shows the flow of the data transmission process of the data transmission / reproducing apparatus 140 at the time of normal reproduction | regeneration of MPEG data. 14 is a flowchart showing a flow of data reproduction processing of the display device 141, which is common during normal reproduction and special reproduction of MPEG data. It is a flowchart which shows the flow of the data transmission process of the data transmission / reproducing apparatus 140 at the time of special reproduction | regeneration of MPEG data. It is a flowchart which shows the flow of the data transmission process of the data transmission / reproducing apparatus 140 at the time of switching the reproduction | regeneration system of MPEG data from special reproduction to normal reproduction. It is a figure which shows the structure of a copy picture. It is a figure which shows typically the image etc. output to TS at the time of normal reproduction | regeneration of MPEG data and special reproduction | regeneration, the monitor 105, etc. It is a flowchart which shows the flow of the data transmission process of the data transmission / reproducing apparatus 140 at the time of special reproduction | regeneration of MPEG data. FIG. 5 is a diagram schematically showing a TS when n = 3 and n = 2 and a frame output to a monitor 105 or the like in slow reproduction at 1/3 speed. FIG. 6 is a diagram schematically showing TS when n = 3 and n = 4 and a frame output to a monitor 105 or the like in frame-by-frame playback with a minimum number of freeze images of 2. It is a flowchart which shows the flow of the data transmission process of the data transmission / reproducing apparatus 140 at the time of switching the reproduction | regeneration system of MPEG data from special reproduction to normal reproduction. It is a figure which shows typically TS, the image output to the monitor 105, etc. when discarding audio ES at the time of special reproduction | regeneration of MPEG data. It is a figure which shows the table used when determining the last field at the time of normal reproduction | regeneration of MPEG data.

Explanation of symbols

106 Video simple encoder 110 Mute generator 111 Stream changeover switch 140 Data transmission / reproduction device 141 Display device

Claims (12)

Reproducing means for reproducing an encoded data sequence including moving image data encoded using intraframe encoding and interframe predictive encoding from a recording medium;
Decoding means for decoding moving image data reproduced by the reproduction means;
Encoding means for outputting encoded moving image data obtained by encoding the moving image data decoded by the decoding means only by the intra-frame encoding;
Transmission that selects one of the moving image data reproduced by the reproducing unit or the encoded moving image data output from the encoding unit, and transmits the selected moving image data to the external device in an encoded form Means,
Normal playback mode in which the moving image data is played back at a normal playback speed, and the transmission means transmits the moving image data played back by the playback means, and the moving image data is played back at a speed different from the normal playback speed; A playback device comprising: mode switching means for switching the special playback mode in which the transmission means transmits moving image data output from the encoding means. Reproducing means for reproducing an encoded data sequence including moving image data encoded using intraframe encoding and interframe predictive encoding from a recording medium;
Decoding means for decoding moving image data reproduced by the reproduction means;
Encoding means for converting the moving picture data decoded by the decoding means into encoded moving picture data composed of intra-frame encoded data and copy picture data for decoding the same data as the reference frame; and
Transmission that selects one of the moving image data reproduced by the reproducing unit or the encoded moving image data output from the encoding unit, and transmits the selected moving image data to the external device in an encoded form Means,
Normal playback mode in which the moving image data is played back at a normal playback speed, and the transmission means transmits the moving image data played back by the playback means, and the moving image data is played back at a speed different from the normal playback speed; A playback device comprising: mode switching means for switching the special playback mode in which the transmission means transmits moving image data output from the encoding means.   3. The reproduction according to claim 2, wherein the special reproduction mode includes a slow reproduction mode, and the encoding means determines an insertion timing of the intra-frame encoded data according to a reproduction speed in the slow reproduction mode. apparatus.   4. The transmission unit according to claim 1, wherein, when switching from the special reproduction mode to the normal reproduction mode, the transmission unit starts transmission from the data of the intra-coded frame in the moving image data. The playback device according to any one of the above.   The said transmission means transmits the discontinuity information which shows the discontinuity of coding data according to switching of the said normal reproduction mode and special reproduction mode, The one of the Claims 1 thru | or 4 characterized by the above-mentioned. Playback device.   The encoded data sequence further includes audio data, and the transmission means transmits the audio data together with the reproduced moving image data in the normal reproduction mode, and the encoding means in the special reproduction mode. The reproduction apparatus according to claim 1, wherein mute data is transmitted together with the moving image data output from.   Determining means for determining whether the moving image data is an interlaced format or a progressive format, and conversion for converting the moving image data in the interlaced format decoded by the decoding unit into a progressive format based on the determination by the determining unit 7. The reproduction apparatus according to claim 1, wherein the encoding unit encodes the moving image data converted by the conversion unit. A reproduction step of reproducing an encoded data sequence including moving image data encoded using intraframe encoding and interframe predictive encoding from a recording medium;
A decoding step of decoding moving image data reproduced from the reproduction step;
An encoding step of outputting encoded moving image data obtained by encoding the moving image data decoded by the decoding step only by the intra-frame encoding;
Transmission that selects one of the moving image data reproduced in the reproduction step or the encoded moving image data output from the encoding step, and transmits the selected moving image data to the external device in an encoded form Process,
Normal playback mode in which the moving image data is reproduced at a normal reproduction speed, and the transmission step transmits the moving image data reproduced in the reproduction step; and the moving image data is reproduced at a speed different from the normal reproduction speed; A reproduction method comprising: a mode switching step in which the transmission step switches between a special reproduction mode for transmitting the moving image data output from the encoding step. A reproduction step of reproducing an encoded data sequence including moving image data encoded using intraframe encoding and interframe predictive encoding from a recording medium;
A decoding step of decoding moving image data reproduced from the reproduction step;
An encoding step of converting the moving image data decoded by the decoding step into encoded moving image data composed of intra-frame encoded data and copy picture data for decoding the same data as the reference frame; and
Transmission that selects one of the moving image data reproduced in the reproduction step or the encoded moving image data output from the encoding step, and transmits the selected moving image data to the external device in an encoded form Process,
Normal playback mode in which the moving image data is reproduced at a normal reproduction speed, and the transmission step transmits the moving image data reproduced in the reproduction step; and the moving image data is reproduced at a speed different from the normal reproduction speed; A reproduction method comprising: a mode switching step in which the transmission step switches between a special reproduction mode for transmitting the moving image data output from the encoding step. On the computer,
A reproduction step of reproducing an encoded data sequence including moving image data encoded using intraframe encoding and interframe predictive encoding from a recording medium;
A decoding step of decoding moving image data reproduced from the reproduction step;
An encoding step of outputting encoded moving image data obtained by encoding the moving image data decoded by the decoding step only by the intra-frame encoding;
Transmission that selects one of the moving image data reproduced in the reproduction step or the encoded moving image data output from the encoding step, and transmits the selected moving image data to the external device in an encoded form Process,
Normal playback mode in which the moving image data is reproduced at a normal reproduction speed, and the transmission step transmits the moving image data reproduced in the reproduction step; and the moving image data is reproduced at a speed different from the normal reproduction speed; A program for causing the transmission step to execute a mode switching step of switching between a special reproduction mode for transmitting the moving image data output from the encoding step. On the computer,
A reproduction step of reproducing an encoded data sequence including moving image data encoded using intraframe encoding and interframe predictive encoding from a recording medium;
A decoding step of decoding moving image data reproduced from the reproduction step;
An encoding step of converting the moving image data decoded by the decoding step into encoded moving image data composed of intra-frame encoded data and copy picture data for decoding the same data as the reference frame; and
Transmission that selects one of the moving image data reproduced in the reproduction step or the encoded moving image data output from the encoding step, and transmits the selected moving image data to the external device in an encoded form Process,
Normal playback mode in which the moving image data is reproduced at a normal reproduction speed, and the transmission step transmits the moving image data reproduced in the reproduction step; and the moving image data is reproduced at a speed different from the normal reproduction speed; A mode switching step in which the transmission step switches between a special reproduction mode for transmitting the moving image data output from the encoding step;
A program for running   A computer-readable storage medium storing the program according to claim 11 or 12.

Images