JP2012015928A - Video transmission device - Google Patents

Abstract

The present invention provides a video transmission apparatus that reduces a delay from when an instruction to start reproduction is given to a video device to when an image is displayed on a television depending on a user's usage tendency and a receiver situation.
A video transmission apparatus transmits a transcode or a stream with a high network bandwidth so that a certain time at the beginning of the video can be displayed with a low delay. The length of the first fixed period is determined from the user's operation tendency, the processing instruction of the player, or the connection receiver information recorded in advance.
[Selection] Figure 3

Description

  The present invention relates to an apparatus for transmitting video.

  As a background art of this technical field, for example, there is JP 2008-206039 A (Patent Document 1). According to the publication, “[Problem] Since transcoding processing needs to be performed after the user's operation is accepted, a large delay occurs until the video is updated after the operation is reflected. For several seconds from the time when the history is retained and operations such as fast forward and rewind are performed, pre-read data is acquired in parallel with the transcode processing of the playback data currently used for playback, and transcoding is performed. After processing, create and save the pre-read data that has been converted, and when the user performs a fast-forward operation, if the pre-read data is available, the pre-read data is instantly sent to the mobile phone. Send to. "

Moreover, there exists Unexamined-Japanese-Patent No. 2010-28516 (patent document 2), for example. The gazette “[Problem] Reduces the waiting time until video is played at the start of video content distribution. [Solution] A basic layer that guarantees a minimum image quality for the video content and the basic layer together. By decoding, it consists of an enhancement layer that can obtain an image quality higher than the result of decoding only the base layer,
The distribution data amount of the base layer detected by the distribution data amount detection means from the start of the distribution of the video content is the first target amount (it is necessary to buffer in order to perform stable reproduction in the video reception device. The basic layer data amount) (initial distribution state) is within the range that does not exceed the available network bandwidth, provided that the available network bandwidth is larger than the encoded bit rate of the basic layer. Is increased from the encoding bit rate, and the distribution bit rate of the higher enhancement layer is decreased accordingly. "

JP 2008-206039 A JP 2010-28516 A

  When a video recorded on a video device is played back on a television, the video device has a configuration in which an information-compressed video stream is sent to the television and the video stream is decoded and displayed on the television side. Both connections are not direct connections, but can be made through a network bus common to other devices, so there are a wide variety of connection configurations, and standardization is being promoted by industry groups such as DLNA (Digital Living Network Alliance). Therefore, it is expected that such a connection form will spread.

  When the video device sends a video stream to the television, the video device outputs the video stream in a format that can be decoded by the television. For example, when a video device records in MPEG-4 AVC (ISO / IEC 14496-10) and a television supports MPEG-2 (ISO / IEC 13818-2) decoding, the video device uses MPEG-4. Transcodes from AVC to MPEG-2 and transmits the video stream to the television.

  Also, since a network bus common to other devices is used, transmission / reception of video streams is affected by delay due to transmission / reception of other data.

  Due to the delay associated with the transcoding process and the decoding delay associated with the network delay, the delay until the playback image is displayed on the TV after the user has issued a special playback instruction such as playback start, fast forward, or rewind to the video device. This is larger than the conventional method of transmitting a video signal using a dedicated line.

  When a stream is transmitted / received via the network bus at the start of reproduction, the delay until display can be reduced to some extent by using a large band exceeding the bit rate necessary for displaying the stream. However, the higher the quality of the video, the higher the bit rate, and the more delayed the display. Although the display can be accelerated by lowering the bit rate, the image quality is lowered. The image quality and the delay until the start of reproduction are in a trade-off relationship, and depending on the user's usage trend and the operation status, which is more important depends on the setting, and it is difficult to set an appropriate setting.

  The technology of Japanese Patent Application Laid-Open No. 2008-206039 is a technology that reduces the delay while pre-reading data to maintain the image quality. However, depending on the usage tendency of the user and the situation of the receiver, the image quality may not be maintained and low. It cannot cope with a case where priority is given to reducing delay using an image quality stream.

  The technology disclosed in Japanese Patent Laid-Open No. 2010-28516 is a method of reducing delay by using hierarchical encoding, and it is necessary for a video device and a television to support decoding of a video stream that has been hierarchically encoded. Since broadcasting using a hierarchically encoded video stream is not performed, televisions that support digital broadcasting often do not support hierarchically encoded video streams.

  In view of the above problems, the present invention provides a video transmission device that reduces the delay from the time when an instruction to start playback is given to a video device to the time when an image is displayed on the television depending on the user's usage tendency and the situation of the receiver The purpose is to provide.

  In order to achieve the above object, the present invention is configured as follows.

  The above object can be achieved by the invention described in the claims.

  According to the present invention, there is provided a video transmission apparatus that reduces a delay from when a user gives an instruction to start playback to a video device to when an image is displayed on a television depending on a user's usage tendency and a receiver situation. can do.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

Schematic showing an example of a video transmission device in the first embodiment Sequence diagram showing until recording video stream is output in the first embodiment Flow chart until the transcoder outputs a stream in the first embodiment Transition of buffer amount of VBV model in the first embodiment Sequence diagram for special playback in the third embodiment Schematic which shows an example of the video transmission apparatus in a 4th Example. Transition of buffer amount of VBV model in the fourth embodiment Schematic which shows an example of the video transmission apparatus in a 5th Example. Transition of VBV without transcoding Sequence diagram when a pause operation is performed in the first embodiment Transition of VBV when transcoding with reduced quantization accuracy

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an example of a video transmission apparatus.

  The video transmission device 100 is connected to the video reception device 300 via the network 200, receives a control signal from the video reception device 300, and outputs a video stream to the video reception device 300 when the control signal is a playback start control signal.

  The video transmission apparatus 100 includes a network I / F 110, a control unit 120, a bus 130, a recording medium 140, a switch 150, a transcoder 160, and a switch 170.

  The network I / F 110 receives information from the network 200, supplies the information to the control unit 120, and outputs data output from the control unit 120 and the switch 170 to the network 200.

  The control unit 120 receives a control signal output from the video reception device 300 through the network 200 and the network I / F 110, and controls the recording medium 140, the switch 150, the transcoder 160, and the switch 170 according to the control signal.

  The bus 130 is a bus that supplies a control signal output from the control unit 120 to the recording medium 140, the switch 150, the transcoder 160, and the switch 170.

  The recording medium 140 is a medium for recording a plurality of video streams. The file name and playback start time are received from the control unit 120, and the corresponding recorded video stream data is output to the switch 150.

  The switch 150 receives a control signal from the control unit 120 via the bus 130, and switches whether the video stream included in the recording medium 140 is output to the transcoder 160 or the switch 170.

  The transcoder 160 receives the video stream via the switch 150, receives the reproducible video stream format from the control unit 120 via the bus 130, transcodes the video stream into the reproducible video stream format, and outputs the output video stream. . In this embodiment, a method for transcoding a video stream to MPEG-2 will be described.

  The switch 170 receives a control signal from the control unit 120 through the bus 130, selects a video stream output from the switch 150 and the transcoder 160, and outputs the video stream to the video reception device 300 through the network I / F 110.

  FIG. 2 is a sequence diagram showing the process from when the video transmitting apparatus 100 receives a playback start control signal from the video receiving apparatus 300 to when it outputs a recorded video stream.

  When the video transmission device 100 and the video reception device 300 are connected to the network 200, they cannot recognize each other's presence. For this reason, the video transmitting apparatus 100 sends the notification 400 to the network at predetermined time intervals. When receiving the notification 400 from the network, the video reception device 300 can obtain the address of the video transmission device 100 and returns a device discovery 410 to the video transmission device 100. By receiving the device discovery 410, the video transmission apparatus 100 can obtain the address of the video reception apparatus 300, and can send data only to the video reception apparatus 300.

  Subsequently, the video reception device 300 outputs the device / service information acquisition 420 to the video transmission device 100 to obtain device / service information 430. The device service information 430 includes services provided by the video transmission apparatus 100, and includes information on a server that distributes a video stream, protocol information used for communication, and the like. The video receiving apparatus 300 can recognize that the video transmitting apparatus 100 can distribute the video stream.

  The video receiving apparatus 300 transmits the device description 440. The device description 440 includes information on a video format that can be played back by the video receiver 300, bit rate information at the start of playback, and the like.

  A user operating the video receiving device 300 performs an operation of displaying the recorded video stream of the video transmitting device 100. At this time, the video receiving device 300 outputs a content acquisition 450 and obtains a content list 460. The content list 460 describes file names held by the video transmission device 100. By obtaining the content list 460, the video receiving device 300 displays a list of file names to the user.

  When the user selects one recorded video stream from the list of file names and performs a playback operation, the video receiver 300 transmits a playback start 470. The playback start 470 includes a playback start command, file name, playback start time, and playback time. Here, the file name indicates information for specifying a recording video stream included in the recording medium. The reproduction start time indicates a time position at which reproduction on the time axis of the recorded video stream indicated by the file name is started. The playback time indicates the time for playback from the playback start time on the time axis of the recorded video stream.

  Upon receiving the playback start 470, the video distribution device 100 performs stream transmission 480 and outputs an output video stream. The video receiving apparatus 300 decodes and displays the obtained output video stream, so that the user can see the reproduced image.

  The process from when the video transmission apparatus 100 receives the reproduction start 470 of FIG. 2 to the stream transmission 480 will be described in detail with reference to FIG.

  Upon receiving the playback start 470, the video transmitting apparatus 100 separates the playback start command, file name, playback start time, and playback time included in the playback start 470 using the control unit 120 in S100. The control unit 120 outputs a control signal to the recording medium 140 so that a recorded video stream equal to the file name is output from the reproduction start time. Also, a control signal is sent to the switch 150 and the switch 170 so that the output video stream of the recording medium 140 is output from the network I / F 110 through the transcoder 160.

  In S110, the recording medium 140 reads the stream and outputs it to the switch 150.

  In S120 and S140, the control unit 120 determines an encoding method for transcoding. As an encoding method, intra-picture encoding (I picture), forward predictive encoding (P picture) for performing predictive encoding with reference to a picture whose playback time is earlier than the picture to be transcoded, and reproduction of the picture to be transcoded. There are three types of bi-predictive coding (B picture) in which predictive coding is performed using pictures before and after time.

  In S130, S150, and S160, each picture is transcoded, and in S170, the picture is compared with the reproduction time information included in the reproduction start 470. When reproduction is not completed, the process returns to S110, and the recorded video stream is read.

  Next, the selection method of the encoding method of S120 and S140 in FIG. 3 will be described.

  The I picture is selected at the start of transcoding or at predetermined intervals.

  The selection of the P picture and the B picture (S140) is a VBV (Video Buffer Verifier) model indicating a buffer transition by a virtual decoder of the output video stream when the transcoder encodes into a video format that can be reproduced by the video receiving device 300. This is done by changing the buffer amount.

  FIG. 4 shows changes in the buffer amount of the VBV model.

  The horizontal axis indicates time, and the vertical axis indicates the buffer amount of the VBV model. t0 to t7 indicate timings at which the decoder decodes and displays the picture. In addition, I0, P1, P2, P3, I6, B4, B5, P9, B7, and B8 indicate the type and display order of encoding, and I0 is a picture displayed at the 0th (first) I picture. Show.

  The transcoder determines the code amount of the first I picture according to the bit rate at the start of playback defined by the device description 440 in FIG.

  The first I picture (I0) is decoded, and the time (t0) when the buffer amount a that does not exhaust the VBV buffer amount even when the buffer amount is reduced is recorded in the picture header as the vbv_delay value. The time t0 is also used to create a DTS (Decoding Time Stamp) value, and the DTS value is added to the output video stream. Thereafter, according to the frame rate, decoding is performed at equal intervals of t1 and t2, and the bit rate is controlled so that the amount of VBV buffer is not exhausted even when a picture is decoded from the VBV buffer.

  The B picture subjected to bi-prediction is predicted using pictures before and after the reproduction time of the picture to be displayed. Therefore, the pictures are rearranged and output at the time of decoding. For this reason, the I picture I6 decoded at t3 to t4 is not displayed at the time t4. On the other hand, since the video stream encoded with only the I picture and the P picture can be displayed in the decoding order, the I picture decoded at t0 can be displayed first, and the delay can be reduced.

  In FIG. 4, the head part (I0 to P3) of the output video stream is composed of I picture and P picture, encoded according to the bit rate at the start of playback defined by the device description 440, and I6 and B4 from the buffer amount of the VBV buffer. Encoding using the B picture is performed from the stage (t3) where it is not depleted even if it is extracted.

  In the video distribution apparatus of the present embodiment, the time to display the image can be shortened by predictively encoding the head portion of the output video stream using the I picture and P picture.

  Also, by decoding the first I picture according to the bit rate at the start of reproduction, the value of point a where decoding of the recorded video stream is started can be lowered, and the time t0 can be advanced.

  FIG. 9 shows the transition of VBV when the transcoding of the head part of the stream is not performed. As shown in the decoding process of I3, when decoding a B picture, in order to decode B0 displayed in advance, I3 used by B0 as a reference image is decoded first. For this reason, vbv_delay is delayed by a maximum of one frame period (33 ms for 30 frames per second) in addition to the delay until buffering up to point a.

  In FIG. 2, by adding pictures I0 to P3 before I6, the output video stream of this embodiment improves the delay of about 33 ms, and the operation response from the start of reproduction to display is improved.

  In addition, the image quality of a moving image is improved by predictive encoding using a B picture at the stage of storing a data amount that does not cause depletion of the VBV buffer. By performing predictive coding using a B picture, the image quality is improved by about 2 dB. Therefore, it is possible to obtain a higher image quality than when transcoding only with I and P pictures except immediately after the start of reproduction.

  In this embodiment, since the delay from the user operation is reduced by the combination method of P picture and B picture used in digital broadcasting, the video receiving apparatus 300 that can decode the video stream output from the video transmitting apparatus 100 with low delay is easy. Can be configured.

  In this embodiment, the recorded video stream is read from the recording medium 140. However, the recorded video stream may be received from the network bus 200, temporarily recorded on the recording medium 140, and then read. Further, a demodulating circuit that receives and demodulates broadcast waves may be provided, and a recorded video stream may be obtained from the demodulating circuit.

  In this embodiment, the transcoder transcodes the head portion of the recorded video stream into an I picture and a P picture, but the head portion may be transcoded with only the I picture.

  By performing transcoding of only I pictures, the processing amount of predictive coding is reduced, so that the processing amount of the transcoder 160 is reduced, the transcoding speed is increased, and the first I0 picture output can be accelerated.

  In this embodiment, the transcoder transcodes the recording video stream. However, when the recording video stream and the output video stream have the same video stream format and the same predictive encoding method, the transcoding is performed from the timing of point b in FIG. You may output without doing.

  By transcoding only the beginning of the recorded video stream, the processing load on the transcoder can be reduced, and even if multiple video receivers are connected to the video distribution device, the transcoder performs time-sharing processing. A video stream can be output.

  In this embodiment, the bit rate information at the start of playback is received from the device description 440. However, any one of the screen resolution, maximum brightness setting, and contrast ratio of the video receiving apparatus 300 is received from the device description 440 in FIG. You may code.

  Here, the screen resolution is described. The bit rate of the output video stream is proportional to the screen resolution. By transcoding according to the screen resolution displayed by the video receiving device 300, the bit rate of the output video stream can be lowered according to the video receiving device, and the delay associated with network transmission can be reduced.

  Similar effects can be obtained with respect to the maximum luminance setting and the contrast ratio.

  In the present embodiment, it has been described that transcoding using I pictures and P pictures is performed until the buffer amount at point b in FIG. 4 is reached, but the predictive encoding method is not changed as shown in FIG. The bit rate may be lowered by lowering the quantization accuracy. When a stream is transmitted by the method shown in FIG. 4, it is necessary to decode two pictures in the period from t3 to t4. By lowering the quantization accuracy and the bit rate, a decoded image can be displayed without decoding two pictures in one frame period. In addition, the value of point a in the recorded video stream can be lowered, and the time t0 can be advanced.

  In this embodiment, the bit rate information at the start of playback is received from the device description 440. However, the bit rate may be lowered using the frequency of generation of the control signal output by the video receiving apparatus 300. When searching for a desired portion from the video being viewed, the user views while repeating fast forward and playback. In this case, since priority is given to searching for the target video portion over the image quality of the video, it is desirable to lower the image quality and increase the operation response. When the video receiving apparatus 300 receives a playback start command and a fast-forward special playback command at short intervals, the bit rate until reaching the buffer amount at point b in FIG. The bit rate information may be transcoded by lowering the value.

Similarly, in the following cases, it is assumed that the improvement of the operation response is required, and the bit rate is determined from the value of the bit rate information at the start of reproduction included in the device description 440 until the buffer amount at point b in FIG. 4 is reached. You may lower and transcode.
When the user feels that the start of playback is slow and presses the playback button a plurality of times, and issues a playback start command a plurality of times before the time t0 when display is performed on the decoder side in FIG. When the next playback command is issued in a time shorter than the playback time included in the playback start 470 in order to start playback of the next program without watching to the end of the stream when selected, the user explicitly When the user wants to improve the response and updates the value of the bit rate information at the start of playback included in the device description 440 by pressing the response improvement operation button in the video receiving device 300. By reducing the bit rate at the start of reproduction, it is possible to balance the operation response and image quality according to the user.

  In this embodiment, the video stream to be transcoded is MPEG-2. However, the present invention is not limited to this, and the present invention can be used for video formats for predictive encoding such as MPEG-4 AVC and VC-1.

  In the second embodiment of the present invention, a method for improving image quality when a video reproduced by a video receiver is paused will be described. The configuration is the same as in FIG.

  FIG. 10 shows a playback method sequence. The same parts as those in FIG.

  During playback, the user performs a pause operation. At this time, a pause 490 is output from the video receiver 300 to the video transmitter 100. The pause 490 includes a pause command and information on the pause time.

  The control unit 120 receives the pause 490 and outputs the name of the file being played and the pause time to the recording medium 140. The recording medium 140 outputs a corresponding recorded video stream.

  The control unit 120 outputs a pause command and a reproducible video stream format to the transcoder 160. The transcoder 160 receives the recorded video stream through the switch 150, performs intra-picture encoding of one picture, and outputs the obtained output video stream as a still image stream 500.

  The forward prediction encoding and the bidirectional prediction encoding can maintain the image quality even at a low bit rate by using the predictive encoding, but the image quality is inferior to the intra prediction encoding because of the accumulation of prediction errors.

  In the video transmission apparatus of the present embodiment, it is possible to improve the picture quality of the screen at the time of pause by encoding the video stream at the time of pause and retransmitting it.

  In the third embodiment of the present invention, a processing method from when a user instruction is given during special reproduction such as fast-forwarding and rewinding until special reproduction operation is performed in the video receiver will be described. The configuration is the same as in FIG.

  FIG. 5 shows a sequence during special playback. The sequence up to the playback start 470 is the same as the sequence shown in FIG. When the user performs a fast-forward operation, the video reception device 300 outputs playback start 471 to 473. The playback start times 471 to 473 are different from each other by, for example, 2 seconds, and the playback time is specified to be 0.5 seconds, for example. The video receiving apparatus 300 receives the corresponding stream transmissions 481 to 483 and reproduces a part of the stream to obtain a fast-forward video.

  When the video transmitting apparatus 100 continuously receives a playback start command including a playback time shorter than a predetermined value, the video transmitting apparatus 100 determines that it is a fast-forward control and transcodes the transcoder at a lower bit rate. The control signal is output through the bus 130.

  The transcoder 160 performs transcoding according to the bit rate specified by the control unit 120.

  In the present embodiment, transcoding is performed by lowering the bit rate at the time of fast-forwarding, thereby reducing the delay caused by the network 200 and improving the response after the user performs a fast-forwarding operation.

  In the present embodiment, the case of fast-forwarding has been described. However, for rewinding, only the time order of the playback start times included in the playback start 471 to 473 is different, the operation of the control unit 120 is the same, and the operation response is improved. can do.

  Further, when the transcoder receives a control signal to be transcoded at a lower bit rate, the transcoder may transcode at a lower video resolution. By reducing the resolution, it is possible to reduce the transcoding processing load and the decoding processing load of the video receiving apparatus, and to improve the operation response. In addition, since the bit amount per pixel increases, the probability that block noise that can be visually recognized due to insufficient quantization accuracy of the transcoded video is reduced.

  Further, when the transcoder receives a control signal to be transcoded at a reduced bit rate, the transcoder may transcode so that more bits are allocated to the I picture than transcoding by a normal reproduction instruction. At the time of special reproduction, the video receiving apparatus may decode and display only the I picture and may not decode the remaining pictures. By allocating many bits to the I picture, the image quality with respect to the bit rate of the output video stream can be improved.

  In the fourth embodiment of the present invention, a method for changing bandwidth allocation when a stream is transmitted from a video transmission apparatus to a network bus according to a user's operation tendency will be described.

  FIG. 6 shows the configuration. The video distribution apparatus 101 in FIG. 6 is obtained by omitting the switch 150, the transcoder 160, and the switch 170 from the configuration of the video distribution apparatus 100 in FIG.

  The recording medium 140 receives a file name and playback start time from the control unit 120 and outputs a corresponding recorded video stream to the network I / F 110.

  The sequence from when the video distribution apparatus 101 receives the playback start control signal from the video reception apparatus 300 to when it outputs the recorded video stream is the same as that in FIG.

  FIG. 7 shows changes in the buffer amount of the VBV model. In this embodiment, since a transcoder is not used, during the period from I0 to B3, the network I / F 110 allocates a network band higher than the bit rate of the recorded video stream and transmits it to the network 200, and an underflow of the buffer occurs. Do not.

The network I / F 110 allocates a high network bandwidth by using the frequency of generation of the control signal output from the video reception device 300. As described in the first embodiment, the control unit 120 holds the number of occurrences of the following conditions for a certain period, and assigns a higher network bandwidth stepwise as the number of occurrences increases.
・ When the user searches for the desired part from the video being watched, by repeating fast forward and playback, the playback start command and the special playback command for fast forward are received at short intervals. Feeling, when the playback button is pressed multiple times, when a playback start command is issued a plurality of times before the time t0 for display on the decoder side in FIG. 7, when the user selects a stream to be played back, When the next playback command is issued in a time shorter than the playback time included in the playback start 470 in order to start playback of the next program without watching to the end, the user explicitly wants to improve response The value of the bit rate information at the start of playback included in the device description 440 is updated by pressing the response improvement operation button in the video receiver 300. In case the embodiment With the above configuration, the operation tendency of the user, because the network bandwidth at the start reproduction is increased in steps, it is possible to balance the operation response and image quality according to the user.

  By discarding the recording of the number of occurrences of the above condition after a certain period, the highly allocated network bandwidth is not retained, and the output of the video distribution apparatus 101 does not always occupy the network bus.

  In this embodiment, the network bandwidth at the start of playback is increased step by step depending on the user's operation tendency. However, any one of the screen resolution, maximum brightness setting, contrast ratio, and input buffer amount information of the video receiving device 300 is selected. The network bandwidth at the start of playback may be determined by receiving from the device description 440 in FIG.

Here, the screen resolution is described. The bit rate of the output video stream is proportional to the screen resolution. By increasing the network bandwidth in accordance with the screen resolution displayed by the video receiving device 300, it is possible to reduce the delay until display according to the video receiving device.
Similar effects can be obtained with respect to the maximum luminance setting, contrast ratio, and input buffer amount.

  In the fifth embodiment of the present invention, a method for changing the recording method of the recorded video stream to the recording medium in the video transmission device according to the user's operation tendency will be described.

  FIG. 8 shows the configuration. In the video distribution apparatus 102 in FIG. 8, the same components as those in the video distribution apparatus 101 in FIG.

  The transcoder 180 obtains a video stream from the network bus 200 via the network I / F 110, obtains a video stream format and screen resolution that can be played back by the video receiver 300 from the control unit 120, and performs transcoding processing. And output to the recording medium 141. The recording medium 141 records a recording video stream output from the transcoder 180.

  The recording medium 141 receives the file name and the reproduction start time from the control unit 120 and outputs the corresponding recorded video stream data to the network I / F 110.

  The sequence from when the video distribution apparatus 100 receives the playback start control signal from the video reception apparatus 300 to when the recorded video stream is output is the same as that in FIG.

  Based on the device description 440 in FIG. 2, the transcoder 180 receives one of the screen resolution, the maximum luminance setting, and the contrast ratio of the video receiving apparatus 300, and based on the flowchart of FIG. 3 so that the transition of the VBV model shown in FIG. Transcode.

Similar to the effect described in the first embodiment, by transcoding according to the screen resolution displayed by the video receiving device 300, the bit rate of the head portion of the recorded video stream is lowered according to the video receiving device, and the transmission is performed on the network. The associated delay can be reduced.
Similar effects can be obtained with respect to the maximum luminance setting and the contrast ratio.
Also, since the transcoded recorded video stream is recorded on the recording medium, the output delay of the video distribution apparatus 102 can be reduced at the start of reproduction.

In the present embodiment, transcoding is performed using information included in the device description 440. However, as described in the first embodiment, the control unit 120 holds the number of occurrences of the following conditions for a certain period, and the greater the number of occurrences, the greater the number of occurrences. The bit rate at the beginning of the recorded video stream may be assigned low.
・ When the user searches for the desired part from the video being watched, by repeating fast forward and playback, the playback start command and the special playback command for fast forward are received at short intervals. Feeling, when the playback button is pressed a plurality of times, when a playback start command is issued a plurality of times before the time t0 for display on the decoder side in FIG. 4. When the user selects a stream to be played back, When the next playback command is issued in a time shorter than the playback time in order to start playback of the next program without watching to the end, the user explicitly wants to improve response, and the video receiving device 300 When the value of the bit rate information at the start of playback included in the device description 440 is updated by pressing a certain response improvement operation button. By adopting such a configuration, it is possible to balance the operation response and the image quality according to the user by lowering the bit rate at the start of reproduction according to the user's operation tendency.

  As mentioned above, although preferred embodiment concerning this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. In addition, a configuration in which two or more embodiments are employed in whole or in part is also possible.

100 Video transmission device 110 Network I / F
DESCRIPTION OF SYMBOLS 120 Control part 130 Bus 140 Recording medium 150 Switch 160 Transcoder 170 Switch 200 Network 300 Image | video receiving apparatus

Claims (19)

A control unit that receives a control signal from the network and interprets the control signal;
A playback unit that reads the video stream from a recording medium on which a recorded video stream including a plurality of pieces of picture information is recorded;
A transcoder that performs information compression based on an instruction from the control unit and outputs an output video stream;
A network I / F for sending the output video stream output by the transcoder to the network;
With
The controller is
When the control signal is a device description, the format of the reproducible video stream included is separated,
When the control signal is a playback start command, the recorded video stream name and playback start time included are separated,
Output the playable video stream format to the transcoder,
Outputting a control signal to output the recorded video stream having the recorded video stream name from the recording medium from the playback start time;
When the transcoder transcodes the video stream to the output video stream in the reproducible video stream format, the transcoder transcodes a predetermined period at the beginning of the recorded video stream with a first bit rate value, Thereafter, transcoding is performed using the second bit rate value. In claim 1,
The video transmission apparatus according to claim 1, wherein the first bit rate value performed by the transcoder is determined by the control signal. In claim 1,
The control unit has history information for holding a history of the control signal,
A video transmitting apparatus characterized in that a transcoding period of a first bit rate value performed by the transcoder is determined based on the history information. In claim 1,
The control unit is connected to the network and separates connection information of a video receiving apparatus that decodes the output video stream from the device description,
A video transmitting apparatus characterized in that a transcoding period of a first bit rate value performed by the transcoder is determined based on the connection information. In claim 1,
The transcoder reads out the picture information 1 corresponding to the playback start time of the recorded video stream as the first bit rate, performs intra-screen coding based on the format of the video stream,
The picture information 2 displayed next to the picture information 1 is subjected to forward predictive encoding with reference to the picture information 1,
A video transmitting apparatus characterized in that subsequent picture information is subjected to forward predictive encoding with reference to encoded picture information. In claim 5,
The transcoder assumes a virtual buffer model for decoding the output video stream,
In the output video stream, even when the output video stream is created using the picture information subjected to bi-predictive coding, the buffer model has a buffer amount that does not run out.
A video transmission apparatus that performs encoding including bi-predictive encoding as the second bit rate. In claim 5,
The transcoder assumes a virtual buffer model for decoding the output video stream,
Even when the recording video stream is output as the output video stream, the buffer model does not exhaust the buffer amount.
A video transmission apparatus that outputs the recorded video stream as the output video stream as the second bit rate. In claim 1,
When the control unit receives a pause control signal, it extracts pause time information included in the control signal and outputs it to the transcoder,
The video transmission device, wherein the transcoder extracts picture information having time information of the pause time information from the recorded video stream, performs intra-screen coding, and outputs the picture information. In claim 1,
The controller is
When the control signal is a fast-forward or rewind control signal, the bit rate information lower than the first bit rate and a special reproduction command are output to the transcoder,
The video transmission apparatus, wherein the transcoder transcodes the recorded video stream at a bit rate described in the bit rate information. In claim 9,
The controller is
When the control signal is a fast-forward or rewind control signal, the transcoder receives resolution information lower than the resolution of the output video stream output by the playback start command, the bit rate information, and the special playback command. Output,
The video transmission apparatus, wherein the transcoder transcodes the recorded video stream at a resolution described in the resolution. In claim 9,
When the transcoder receives the special reproduction instruction and the bit rate information, the transcoder allocates more bits to picture information to be subjected to intra-picture encoding as compared with the reproduction start instruction. A control unit that receives a control signal from the network and interprets the control signal;
A playback unit that reads a recorded video stream from a recording medium on which a recorded video stream including a plurality of pieces of picture information is recorded;
A network I / F for sending the recording video stream output from the recording medium to the network;
With
The controller is
When the control signal is a playback start command, the recorded video stream name and playback start time included are separated,
Outputting a control signal to output the recorded video stream having the recorded video stream name to the recording medium from the playback start time;
The video transmission apparatus characterized in that the network I / F outputs a predetermined period at the beginning of the recorded video stream at a first bit rate value and then outputs at a second bit rate value. In claim 12,
The video transmission apparatus according to claim 1, wherein the first bit rate value output from the recording medium is determined by the control signal. In claim 12,
The control unit has history information for holding a history of the control signal,
An image transmitting apparatus characterized in that an output period of a first bit rate value output from the recording medium is determined based on the history information. In claim 12,
The control unit erases a control signal that has passed a predetermined period from the history information, and determines an output period of a first bit rate value output from the recording medium based on the history information. Video transmission device. In claim 12,
The control unit has connection information of a video receiving device connected to the network and decoding the output video stream,
An image transmitting apparatus characterized in that an output period of a first bit rate value output from the recording medium is determined based on the connection information. A control unit that receives a control signal from the network and interprets the control signal;
A playback unit that reads a recorded video stream from a recording medium on which a recorded video stream including a plurality of pieces of picture information is recorded;
A network I / F for sending the recording video stream output from the recording medium to the network;
With
The network I / F is
By the control information given from the control unit,
Output a predetermined period at the beginning of the recorded video stream from the recording medium by the first method, and then output by the second method,
Further, the control unit has history information for holding a history of the control signal,
A video transmitting apparatus characterized in that a period of the first method is determined based on the history information. A control unit that receives a control signal from the network and interprets the control signal;
A playback unit that reads a recorded video stream from a recording medium on which a recorded video stream including a plurality of pieces of picture information is recorded;
A network I / F for sending the recording video stream output from the recording medium to the network;
With
The network I / F is
By the control information given from the control unit,
Output a predetermined period at the beginning of the recorded video stream from the recording medium by the first method, and then output by the second method,
In addition, the control unit uses the control signal to
A video transmitting apparatus characterized in that a period of the first method is determined based on the history information. A control unit that receives a control signal from the network and interprets the control signal;
A playback unit that reads a recorded video stream from a recording medium on which a recorded video stream including a plurality of pieces of picture information is recorded;
A network I / F for sending the recording video stream output from the recording medium to the network;
With
The network I / F is
By the control information given from the control unit,
Output a predetermined period at the beginning of the recorded video stream from the recording medium by the first method, and then output by the second method,
Further, the control unit has connection information of a video receiving device connected to the network and decoding the output video stream,
An image transmitting apparatus characterized in that an output period of a first method for outputting from the recording medium is determined based on the connection information.

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