JP2010239575A - Content playback apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce video signal playback display processing, when it is determined that decoding of audio signals is delayed. <P>SOLUTION: An audio output controller 54f reads out audio signals decoded by an audio decoder 54d and stored in a decoded audio buffer 54e; sends the audio signals to a D/A converter 25 to output them from a loudspeaker; and monitors the quantity of audio signals stored in the decoded audio buffer 54e. When the quantity is less than a predetermined threshold, a video decoder 54b is instructed to store video images into a decoded video buffer 54c, by thinning a video frame decoded by the video decoder 54b. Thus, the processing for an application unit 53 for processing the video frames stored in the decoded video buffer 54c and for writing them into a display RAM 22 is reduced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a content reproduction apparatus, and more particularly to suppression of sound interruption of reproduced audio.

  It is known that when reproducing the encoded content, processing such as decoding is performed by a general-purpose CPU (Central Processing Unit) without using a dedicated DSP (Digital Signal Processor). Here, the content includes at least video and audio. Since a general-purpose CPU also performs processes other than this decoding, the decoding cannot be performed at a sufficient speed under a heavy load, and reproduction may be interrupted. In particular, when sound interruption occurs due to delay in decoding of an audio signal, content viewers are likely to feel uncomfortable, and suppression of sound interruption is desired.

  Therefore, it is monitored whether or not the playback is performed at a necessary speed, and when it is determined that the playback speed is slow, for example, when the playback of the video is stopped or a video having a plurality of image quality is obtained, Processing for changing to low-quality video playback is known (for example, see Patent Document 1).

JP 2001-346139 A (2nd and 7th pages, FIG. 4)

  However, in the method disclosed in Patent Document 1 described above, there is a problem that the viewer feels uncomfortable when the reproduction of the video is stopped. There was a problem that could not be changed to video playback.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a content playback apparatus that reduces video signal playback display processing when it is determined that audio signal decoding is delayed. .

  In order to achieve the above object, a content playback apparatus of the present invention is a content playback apparatus for playing back content including at least an encoded video frame and an encoded audio signal, wherein the encoded video is Video decoding means for decoding the frame, application means for displaying the video frame decoded by the video decoding means on the display means, audio decoding means for decoding the encoded audio signal, and decoding by the audio decoding means Decoded speech storage means for storing the decoded speech signal, and speech output control means for outputting the decoded speech signal stored in the decoded speech storage means from a speaker, and stored in the decoded speech storage means When the amount of the decoded audio signal is less than a predetermined threshold, the video decoding means Thinned and decode and / or the application unit may be displayed on the display means by thinning out video frames decoded by said video decoding means.

  According to the present invention, when it is determined that the decoding of the audio signal is delayed, it is possible to reduce the reproduction / display processing of the video signal.

The block diagram which shows the hardware constitutions of the mobile communication apparatus which concerns on embodiment of this invention. The block diagram which shows the software structure of the mobile communication apparatus which concerns on embodiment of this invention. The block diagram which shows the detailed structure of the content decoding part which concerns on embodiment of this invention. The flowchart of the content reproduction output operation | movement by the application part which concerns on embodiment of this invention. The flowchart of the operation | movement which reduces the process of the video signal by the audio | voice output control part which concerns on embodiment of this invention. The figure which shows the condition of the reduction | restoration of the process of the video signal which concerns on embodiment of this invention.

  Hereinafter, an embodiment of a mobile communication device to which a content reproduction device according to an embodiment of the present invention is applied will be described with reference to the drawings. FIG. 1 is a block diagram showing a hardware configuration of a mobile communication device according to an embodiment of the present invention.

  The mobile communication device includes a mobile communication network communication unit 11 belonging to a baseband group, an antenna 11a that transmits and receives radio waves between a base station (not shown) of the mobile communication network, a speaker 11b for calling, Microphone 11c for call, baseband CPU 12, near field communication unit 21 belonging to application group, antenna 21a for transmitting / receiving radio waves to / from an access point (not shown) of the near field communication network, and display A RAM (Random Access Memory) 22, a display unit 23, an input unit 24, a D / A (Digital / Analog) conversion unit 25, a content reproduction speaker 26, an application CPU 27, and each unit of the two groups. It consists of a primary storage unit 31 and a secondary storage unit 32 to be accessed.

  In this block diagram, all the units are illustrated as being connected by a common bus, but this is for the sake of easy understanding and is not limited thereto. A configuration including a bus that connects each unit belonging to the baseband group, a bus that connects each unit belonging to the application group, and a bus that connects these buses may be used.

  In addition, although the primary storage unit 31 and the secondary storage unit 32 are accessed by the respective units of the two groups, this is for ease of understanding and is not limited thereto. Instead of or in addition, a configuration having a primary storage unit dedicated to each group and a secondary storage unit may be used.

  The operation of each part of the hardware of the information processing apparatus according to the embodiment of the present invention configured as described above will be described with reference to FIG.

  The mobile communication network communication unit 11 amplifies, converts and demodulates a high frequency signal transmitted from a base station (not shown) of the mobile communication network and received by the antenna 11a, and converts the digital audio signal obtained thereby into an analog audio signal. It converts into a signal, amplifies it, and sends it to the speaker 11b. The obtained control signal is sent to the baseband control unit. Here, the baseband control unit is software using the baseband CPU 12 and controls each unit belonging to the baseband group.

  The mobile communication network communication unit 11 amplifies the analog audio signal output from the microphone 11c, modulates the digital audio signal converted from the analog audio signal, and the control signal output from the baseband control unit, converts the frequency, and amplifies the signal. Then, a high frequency signal is obtained and transmitted from the antenna 11a.

  The baseband CPU 12 is used by software related to each unit belonging to the baseband group including the baseband control unit, and operates with reference to the primary storage unit 31 and the secondary storage unit 32.

  The short-range communication unit 21 performs wireless LAN (Local Area Network) communication. That is, a high-frequency signal transmitted from an access point (not shown) of the Internet network and received by the antenna 21a is amplified, frequency-converted and demodulated, and a control signal obtained thereby is sent to the application control unit. The application control unit is software that uses the application CPU 27 and controls each unit belonging to the application group. The short-range communication unit 21 stores the obtained digital content signal in a content buffer in the application group.

  All the buffers including the content buffer are storage areas set in the primary storage unit 31 and / or the secondary storage unit 32. The storage area management method is a file system or cyclic method, that is, when information is sequentially stored in the storage area and information is stored in all areas, the oldest stored information is stored. It does not matter whether the information is stored in a new area or is assigned to a variable and has no structure.

  The short-range communication unit 21 further modulates, frequency converts, and amplifies the control signal output from the application control unit, obtains a high-frequency signal, and transmits it from the antenna 21a.

  The display RAM 22 stores an image image displayed on the display unit 23 written by software using the application CPU 27 in accordance with an instruction from the application control unit. This image image is an arbitrary still image, and includes an image of content, letters / numbers including a cursor, and the like.

  The display unit 23 is, for example, an LCD (Liquid Crystal Display) with a backlight, and displays an image image stored in the display RAM 22 or stops display according to control of the application control unit.

  The input unit 24 designates a telephone number of a communication partner, and a plurality of keys including a numeric key for inputting hiragana characters, alphabetic characters and symbol characters by a toggle type input method, a cursor movement key, and a scroll key. It consists of keys including function keys. When the key of the input unit 24 is pressed, the identifier of the key is notified to the application control unit.

  The D / A conversion unit 25 converts a digital audio signal, which is a PCM (Pulse Code Modulation) signal transmitted by software using the application CPU 27 in accordance with an instruction from the application control unit, into an analog audio signal, and converts the converted analog audio signal. An audio signal is generated from the speaker 26.

  The application CPU 27 is used by software related to each unit belonging to the application group including the application control unit, and operates with reference to the primary storage unit 31 and the secondary storage unit 32.

  FIG. 2 is a block diagram showing a software configuration of the mobile communication apparatus according to the embodiment of the present invention, and also shows a storage configuration. This mobile communication device includes a baseband control unit 41 belonging to a baseband group, an application control unit 51 belonging to an application group, a content buffer 52 in which content received by the short-range communication unit 21 is stored, and an application unit 53 And a content decrypting unit 54 and an image editing library 55.

  A baseband control unit 41 that controls the entire baseband group and an application control unit 51 that controls the entire application group are connected. With this connection, information can be transmitted / received even between parts belonging to different groups, and in this embodiment, the information transmission / reception is not performed via the baseband control unit 41 and the application control unit 51. Explained.

  FIG. 3 is a block diagram showing a detailed configuration of the content decrypting unit 54, and also shows a flow of content until the content stored in the content buffer 52 is reproduced by the application unit 53. Here, the arrows indicate the flow of content.

  The content decoding unit 54 is connected to the content buffer 52, a separation unit 54a, a video decoding unit 54b, an application unit 53, and a decoded video buffer 54c that stores a video signal decoded by the video decoding unit 54b. The audio decoding unit 54d, the decoded audio buffer 54e in which the audio signal decoded by the audio decoding unit 54d is stored, and the audio output control unit 54f connected to the D / A conversion unit 25.

  The operation of each part of the software of the information processing apparatus according to the embodiment of the present invention configured as described above will be described with reference to FIGS.

  The application unit 53 is a browser, for example, and instructs the short-range communication unit 21 to receive content. Then, the content stored or being stored in the content buffer 52 by the reception is displayed on the display unit 23 and generated from the speaker 26. Here, H. The video and audio content encoded by the H.263 system, the MP3 system, or the like is decoded by the content decoding unit 54, and the decoded audio signal is instructed to the content decoding unit 54 to be generated from the speaker 26. On the other hand, the application unit 53 creates an image to be displayed from the decoded video signal and an image that does not need to be decoded by the content decoding unit 54 and causes the display unit 23 to display the image.

  The operation of each unit of the content decrypting unit 54 will be described. Each unit of the content decryption unit 54 operates according to an instruction from the application unit 53. The separation unit 54 a is stored in the content buffer 52 and designated by the application unit 53. Video and audio content encoded by the H.263 system, the MP3 system, or the like is read. Then, the content is separated into a video signal and an audio signal, and the video signal is sent to the video decoding unit 54b and the audio signal is sent to the audio decoding unit 54d.

  The video decoding unit 54b decodes the received encoded video signal. Here, the encoded video signal is a signal in which a still image (hereinafter referred to as a video frame) cut out at a predetermined time interval is encoded. Therefore, decoding is performed for each video frame. Then, when there is a request for a decoded video frame from the application unit 53, the decoded video buffer 54c is stored together with the video frame and a time stamp attached when the video frame was encoded. To provide.

  Note that the video decoding unit 54 b does not necessarily provide all of the decoded video frames to the application unit 53. In accordance with an instruction from the audio output control unit 54f, a part thereof may not be provided, that is, thinned out. Decoding of the thinned video frame does not need to be performed. For example, when one of the video frames is intra-frame encoded and a predetermined number of video frames following the video frame are inter-frame encoded with reference to the immediately preceding video frame, If an encoded video frame is skipped, it is not necessary to decode that frame. However, when providing an interframe-encoded video frame that refers to a thinned video frame, the thinned video frame is decoded.

  The audio decoding unit 54d decodes the received encoded audio signal. Here, the encoded audio signal is a signal obtained by encoding an audio signal cut out with a predetermined time width. Therefore, each extracted audio signal is decoded, and the obtained digital audio signal, which is a PCM signal, is stored in the decoded audio buffer 54e. A time stamp is attached to a part of the encoded audio signal. Therefore, the time stamp is stored in the decoded audio buffer 54e together with the decoded audio signal.

  The audio output control unit 54f refers to the time stamp stored in the decoded audio buffer 54e, and sends the decoded audio signal stored therein to the D / A conversion unit 25 to generate it from the speaker 26. The audio output control unit 54f deletes the generated audio signal from the decoded audio buffer 54e.

  The audio output control unit 54f monitors the amount of the decoded audio signal stored in the decoded audio buffer 54e. When this amount is smaller than the predetermined amount, it is determined that the processing of the audio decoding unit 54d is delayed, that is, the load on the application CPU 27 is excessively high, and the video decoding unit 54b receives all of the encoded video frames. The application unit 53 is instructed not to be provided without being provided.

  The image editing library 55 is a software package for editing a still image. That is, synthesis of a given still image, change in color tone, and change in size are performed. Here, the change in size includes reduction, enlargement, and partial cutout. Reduction or enlargement may involve changing the number of pixels representing a still image in accordance with the screen resolution of the display unit 23. Still images include characters that are displayed as images.

  Hereinafter, an operation for reducing the reproduction display processing of the video signal when it is determined that the decoding of the audio signal by the mobile communication device according to the embodiment of the present invention is delayed will be described.

(Content reproduction output operation by the application unit 53)
FIG. 4 shows a flowchart of the content reproduction output operation by the application unit 53. The application unit 53 starts a content reproduction output operation by a predetermined key operation of the input unit 24 (step S101), and instructs the short-range communication unit 21 to start receiving the content specified by the key operation (step S101). S102).

  This content is The application unit 53 includes the video encoded by the H.263 system and the audio content encoded by the MP3 system. Instruct each unit of the content decoding unit 54 to decode the content encoded by the H.263 method and the MP3 method and to generate a decoded audio signal from the speaker 26 (step S103).

  Then, the presence / absence of a video frame not displayed on the display unit 23 is determined (step S104). This determination is made by H.H. This can be determined by the time required to reproduce the content included in the beginning of the content encoded by the H.263 method and the time stamp added to the video frame. Further, the application unit 53 may make a determination by inquiring whether there is a video frame that is not provided to the video decoding unit 54b.

  If there is a video frame that is not displayed, the application unit 53 requests the video frame to be displayed next from the video decoding unit 54b, and acquires the video frame from the decoded video buffer 54c (step S105). Then, in the content received by the short-range communication unit 21, the application unit of the display unit 23 combines information that does not require the content decoding unit 54 to decode, for example, a still image or a character. An image displayed in the window assigned to 53 is created using the image editing library 55 (step S106). This displayed image is, for example, an image according to the arrangement in the page specified in the Web page.

  The created image to be displayed is displayed on the display unit 23 by being stored in the display RAM 22 at the time indicated by the time stamp added to the video frame acquired in step S105 (step S107). Move to judgment operation. In this way, by referring to the time stamp and storing it in the display RAM 22, the video displayed by the operation of step S107 and the audio output by the content decoding unit 54 are synchronized.

  If a change in the size of the window allocated to the application unit 53, a scroll request, or the like is performed by a predetermined key operation of the input unit 24 during the loop operation of step S104 to step S107, the application unit 53 In step S106, an image according to the request is created using the image editing library 55. In step S105, if a video frame cannot be acquired, it is determined that there is no video frame not displayed (not shown).

  On the other hand, if there is no undisplayed video frame in step S104, the application unit 53 ends the content reproduction output operation (step S108). Here, the operation of each unit of the short-range communication unit 21 and the content decryption unit 54 is stopped. Since the image stored in the display RAM 22 is not changed, the display on the display unit 23 is not erased.

(Operation for reducing video signal reproduction / display processing by the audio output control unit 54f)
FIG. 5 is a flowchart of an operation for reducing the video signal reproduction / display processing by the audio output control unit 54f. The audio output control unit 54f starts operation according to the instruction of the application unit 53 (step S201), reads out the decoded audio signal from the decoded audio buffer 54e, sends it to the D / A conversion unit 25, and generates it from the speaker 26 The read audio signal is deleted from the decoded audio buffer 54e (step S202). Here, the amount of the audio signal to be read out is an audio signal decoded once or a plurality of times. For example, the amount depends on the size of the storage area provided in the audio output control unit 54f.

  Then, the audio output control unit 54f compares the data amount of the audio signal stored in the decoded audio buffer 54e with the first threshold A (step S203). If it is equal to or greater than the first threshold A, the data amount of the audio signal stored in the decoded audio buffer 54e is compared with a second threshold B exceeding the first threshold A (step S204). If it is greater than or equal to the second threshold B, the load on the application CPU 27 is examined (step S205). This load can be checked by inquiring the OS function of the application control unit 51.

  When the load of the application CPU 27 is equal to or less than the predetermined threshold, the audio output control unit 54f instructs the video decoding unit 54b to provide all video frames to the application unit 53 (step S206), and the video signal The operation for reducing the reproduction display process is terminated (step S207).

  If it is less than the threshold value B in step S204, and if the predetermined threshold value is exceeded in step S205, the audio output control unit 54f ends the operation for reducing the video signal reproduction display processing (step S207). Note that if it is equal to or greater than the first threshold A in step S203, the audio output control unit 54f immediately performs step unless the instruction to the video decoding unit 54b immediately provides a part of video frames to the application unit 53. Moving to S207, the operation is the same as ending the operation of reducing the video signal reproduction / display processing.

  If it is less than the first threshold A in step S203, the audio output control unit 54f instructs the application unit 53 to provide a part of the video frames (step S208), and performs video signal reproduction display processing. The reduction operation is terminated (step S207).

  In the operation of step S208, if the instruction to the video decoding unit 54b immediately before does not provide all the video frames to the application unit 53, the audio output control unit 54f immediately moves to step S207, and the video signal This is the same operation as ending the operation for reducing the reproduction display processing. Here, when the audio output control unit 54f starts operation, the instruction to the immediately preceding video decoding unit 54b is considered to provide all the video frames to the application unit 53.

  It is a well-known technique to compare the data amount of the audio signal stored in the decoded audio buffer 54e with two threshold values, that is, the first threshold value A and the second threshold value B. That is, when compared with one threshold value, when the data amount frequently fluctuates between the threshold value and less than the threshold value, an instruction to provide all video frames in step S206 and a part of step S208 are provided. There is a possibility that an instruction to provide a video frame is frequently performed unnecessarily. If compared with two threshold values, this frequent instruction is not given.

(Operation for providing all or part of the decoded video frame by the video decoding unit 54b)
The video decoding unit 54b receives a video from the application unit 53 when receiving an instruction from the audio output control unit 54f to provide all video frames to the application unit 53, and when the video decoding unit 54b starts operating. In response to the frame request, one decoded video frame to be displayed next on the display unit 23 is stored in the decoded video buffer 54c and provided to the application unit 53. Here, a time stamp indicating the time when the video frame should be displayed on the display unit 23 is attached to the video frame.

  When receiving an instruction from the audio output control unit 54f to provide some video frames to the application unit 53, the video decoding unit 54b responds to the video frame request from the application unit 53 with the decoded video frame. A predetermined percentage of the video frames, for example, one video frame is selected in order of time stamp, and one video frame to be displayed next on the display unit 23 is decoded with the selected video frame. The data is stored in the video buffer 54 c and provided to the application unit 53.

  The video decoding unit 54b refers to the time stamp to detect a video frame that has already been determined that the time to be displayed on the display unit 23 has passed, and does not provide the detected frame. For this reason, some video frames may be discarded regardless of an instruction from the video decoding unit 54b.

  As described above, the video decoding unit 54b immediately changes the number of video frames provided to the application unit 53 in accordance with an instruction from the audio output control unit 54f, and changes the load of the application CPU 27 with the minimum delay time. Can do. For this reason, it is effective to store one video frame in the decoded video buffer 54 c, and storage management such as deleting the video frame stored in the decoded video buffer 54 c without providing it to the application unit 53. There is no need to do.

  Since the two processing units of the video decoding unit 54b and the application unit 53 access this buffer, the storage management is a complicated process including exclusive control. On the other hand, according to the present embodiment, since the decoded video frame is stored in the video decoding unit 54b until it is stored in the decoded video buffer 54c, it is easily managed by the video decoding unit 54b.

  How the video frames provided to the application unit 53 are reduced by the above-described operation for reducing the reproduction display of the video signal will be described with reference to FIG. Here, the horizontal axis is time, which is the time indicated by a clock that is referred to in order to determine whether or not a time stamp for displaying a video frame has been reached.

  FIG. 6A shows a request for a video frame from the application unit 53 when the decoding is performed at a sufficient speed and the playback / display processing of all the video frames is performed, and video decoding is performed in response to the request. The video frame provided by the unit 54b is shown. When the request 1 is transmitted from the application unit 53, in response to the request, the video decoding unit 54b provides the video frame 1 at an appropriate time, that is, sufficiently before the time T1 at which the frame is displayed. Thus, the application unit 53 displays the video frame.

  Thereafter, when the request i is transmitted from the application unit 53, the video decoding unit 54b provides the video frame i at an appropriate time in response to the request, so that the application unit 53 displays the video frame. The situation is indicated by a natural number i from 1 to 6 (1 ≦ i ≦ 6).

  FIG. 6B shows a situation in which after the video frame 1 is provided at an appropriate time, the audio output control unit 54f instructs the video decoding unit 54b to provide half of the video frame. When the request 2 is subsequently transmitted from the application unit 53, in response to the request, the video decoding unit 54b displays the video frame 3 at an appropriate time without providing the video frame 2, that is, the frame is displayed. By providing it sufficiently before the time T3, the application unit 53 displays the video frame.

  Note that the time at which the video frame 3 is provided has no significant meaning. For example, even if the frame is provided well before time T2, the video frame is displayed at time T3 by the time stamp provided with the video frame.

  Subsequently, when the request 3 is transmitted from the application unit 53 (this transmission is after time T3 when the already provided video frame 3 is displayed), in response to the request, the video decoding unit 54b The video frame 5 is provided at an appropriate time without providing the video frame 4. Thus, the video frame 2 and the video frame 4 are not provided.

  FIG. 6C shows a situation where the application unit 53 is not processed at a sufficient speed after the video frame 1 is provided at an appropriate time, and the processing for requesting the video frame to the video decoding unit 54b is delayed. Show. The request 2 is subsequently transmitted from the application unit 53. The request is transmitted after time T2 when the video frame 2 is displayed. Therefore, the video decoding unit 54b provides the video frame 3 at an appropriate time without providing the video frame 2, that is, sufficiently before the time T3 when the frame is displayed. The video frame is displayed.

  Subsequently, the request 3 is transmitted from the application unit 53. The request is transmitted after time T4 when the video frame 4 to be displayed next to the video frame 3 already displayed is displayed according to the time stamp. It was. Therefore, the video decoding unit 54b provides the video frame 5 at an appropriate time without providing the video frame 4, that is, sufficiently before the time T5 when the frame is displayed. Next, a request 4 is transmitted from the application unit 53. The request is transmitted sufficiently before the time T6 when the video frame 6 is displayed. Therefore, the video decoding unit 54b provided the video frame 6 at an appropriate time.

  According to this situation, video frames that are not provided to the application unit 53 are not provided with regularity, for example, one of the two displayed in succession is not provided, but when the application CPU 27 is heavily loaded, the application unit 53 By reducing the number of video frames to be reproduced and displayed, the high load can be reduced.

(Modification of the embodiment)
In the above description, the audio output control unit 54f instructs the video decoding unit 54b to provide the application unit 53 with all video frames or some video frames. It is not a thing. The ratio of the video frames to be provided to the total video frames may be indicated by three or more stages and further by a floating point number. Naturally, the smaller the amount of data stored in the decoded audio buffer 54e, the less the video frame is instructed to be provided.

  In the above description, it is assumed that the audio output control unit 54f monitors the amount of data stored in the decoded audio buffer 54e. Since the audio output control unit 54f reads out the audio signal stored in the decoded audio buffer 54e at approximately predetermined time intervals, it is suitable for monitoring the amount of the stored signal. However, the present invention is not limited to this, and the audio decoding unit 54d accessing the buffer may monitor. Alternatively, the video decoding unit 54b that has received an instruction from the audio output control unit 54f may monitor.

  Furthermore, the application unit 53 may monitor, and the time interval for requesting the video frame from the video decoding unit 54b may be changed based on the monitoring result. In this case, there is a possibility that a device-dependent part occurs in the operation of the application unit 53. However, if the possibility that the viewer feels uncomfortable due to the display by the application unit 53 is small even if the video frame is thinned out, appropriate processing depending on the application performed by the application unit 53, such as a large thinning out, is possible.

  In the above description, the content decrypted by the content decrypting unit 54 includes one video and one audio. However, the present invention is not limited to this. Each may be plural. The video decoding unit 54b and the audio decoding unit 54d are software that uses the application CPU 27, and can be decoded without any problem by generating a plurality of tasks.

  Here, when a plurality of videos are included, in providing video frames to the application unit 53, it is appropriate that the above-described operation for reducing the playback display processing is performed on the video frames of all videos. In addition, when the video to which this operation is applied is limited or the order in which the video is applied is specified and applied to a video, the amount of data stored in the decoded audio buffer 54e has increased or does not decrease, It may not be applied to other images. When a plurality of sounds are included, the sound output control unit 54f selects one of them. Alternatively, a plurality of sounds are added by the D / A conversion unit 25.

  In the above description, the short-range communication unit 21 performs wireless LAN communication, but is not limited thereto. For example, it may communicate with a device connected to the Internet by being connected to a hub connected to the Internet via a cable. Further, Bluetooth (registered trademark: Bluetooth) communication may be performed.

  In the above description, it is assumed that the content reproduced by the application unit 53 is content received by the short-range communication unit 21. Since the short-range communication unit 21 belongs to the application group, when the communication by the short-range communication unit 21 is unstable and frequent retransmissions occur, an interrupt for notifying the application control unit 51 of the communication status is generated. The effect of the present invention is great when the load of the application CPU 27 is large, such as when it occurs frequently.

  However, the content to be reproduced is not limited to the content received by the short-range communication unit 21. In the case of content received by the mobile communication network communication unit 11, in the case of content stored in the secondary storage unit 32, the removable external storage medium connected to the external storage medium connection unit (not shown) This applies to any case where the content is stored. Further, when the external storage medium connection unit belongs to the application group, the effect of application is great.

  In the above description, the content reproduced by the application unit 53 is H.264. It is assumed that the encoding is performed by the H.263 method and the MP3 method, but this is an example. Other methods such as H.264. Even if it is encoded by the H.264 system, the present invention can be applied without any change.

  In the above description, the mobile communication device includes two CPUs, but is not limited thereto. There is no limitation on the number of CPUs, and an effect of suppressing sound interruption caused by the high load of the CPU performing content reproduction can be obtained.

  Although the above description has been made taking an example in which the present invention is applied to a mobile communication device, the present invention is not limited to this. The present invention is naturally applicable to an apparatus for reproducing any content regardless of whether it is a fixed type or a portable type. The present invention is not limited to the above configuration, and various modifications are possible.

11 Mobile Communication Network Communication Unit 12 Baseband CPU
21 Short-range communication unit 22 Display RAM
23 Display Unit 24 Input Unit 25 D / A Conversion Unit 26 Speaker 27 Application CPU
41 Baseband control unit 51 Application control unit 52 Content buffer 53 Application unit 54 Content decoding unit 54a Separation unit 54b Video decoding unit 54c Decoded video buffer 54d Audio decoding unit 54e Decoded audio buffer 54f Audio output control unit 55 Image editing library

Claims (5)

A content playback device for playing back content including at least an encoded video frame and an encoded audio signal,
Video decoding means for decoding the encoded video frame;
Application means for displaying on the display means the video frame decoded by the video decoding means;
Audio decoding means for decoding the encoded audio signal;
Decoded speech storage means for storing the speech signal decoded by the speech decoding means;
Voice output control means for outputting the decoded voice signal stored in the decoded voice storage means from a speaker;
When the amount of the decoded audio signal stored in the decoded audio storage unit is less than a predetermined threshold, the video decoding unit decodes the encoded video frame by thinning out and / or the application unit Is a content reproducing apparatus characterized in that the video frame decoded by the video decoding means is thinned out and displayed on the display means. When the amount of the decoded audio signal stored in the decoded audio storage unit is less than a predetermined threshold, the audio output control unit sends a part of the decoded video frame to the application unit. The content reproduction apparatus according to claim 1, wherein the content reproduction apparatus is provided. 2. The content reproduction apparatus according to claim 1, wherein the application unit changes the size of the video frame decoded by the video decoding unit and causes the display unit to display the video frame. 2. The content reproduction apparatus according to claim 1, wherein the application unit synthesizes the video frame decoded by the video decoding unit and a still image included in the content and displays the synthesized image on the display unit. 2. The content reproduction apparatus according to claim 1, wherein the application unit synthesizes the video frame decoded by the video decoding unit and characters included in the content and causes the display unit to display them.

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