JP2006270595A - Image encoding circuit, image encoding device, and multiplexing circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image encoding circuit which is capable of converting a local time stamp normally into a PTS even if O revolving occurs. <P>SOLUTION: An ES parse unit 21 divides an H. 264 elementary stream by a frame, outputs the divided H. 264 elementary stream divided by the frame as a PES payload, analyses the component element of each PES payload, and extracts information necessary for a time stamp conversion process in a PTS generating unit 23. A O-revolving determination unit 22 determines whether the O-revolving occurs or not, and when it is found that the O-revolving has not occurred, a PTS generating unit 23 generates the PTS by normal processing, by using a normal processing means 23a. When the O-revolving has occurred, the PTS generating unit 23 adds a correction δ which is obtained on the basis of the bit length of the local time stamp of the previous frame to the PTS obtained by usual processing by using a O-revolving processing means 23b, and a new PTS composed of the original PTS and a correction value δ is made to serve as the PTS. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a video encoding apparatus that encodes a moving image signal using a moving image compression method in which a local time stamp can be set with an arbitrary bit length.

  As is well known, for example, video compression methods such as ITU-T (International Telecommunication Union-Telecommunication Sector) recommendation H.264 make it possible to set the local time stamp to an arbitrary bit length (1 to 32 bits). (For example, refer nonpatent literature 1).

However, since the bit length can be arbitrarily set, there is a possibility of causing 0 rounds depending on the set value. There has been a problem that when the encoder makes 0 rounds, the local time stamp cannot be normally converted into a PTS (Presentation Time Stamp).
"H.264 / AVC textbook" supervised by Satoshi Okubo, Impress Communications Inc., July 30, 2004.

In a conventional video encoding device, when a moving image compression method capable of setting a local time stamp to an arbitrary bit length is adopted, there is a possibility of causing 0 rounds depending on the set value of the bit length. When this occurs, there is a problem that the local time stamp cannot be normally converted to PTS.
The present invention has been made to solve the above-described problem. A video encoding circuit, a video encoding device, and a multiplexing circuit capable of normally converting a local time stamp into PTS even when 0 rounds occur are provided. The purpose is to provide.

  In order to achieve the above object, the present invention uses a moving image compression method in a video encoding circuit that encodes a moving image signal using a moving image compression method in which a time stamp can be set with an arbitrary bit length. An encoding unit that encodes a moving image signal into encoded data in units of frames and adds a time stamp to the encoded data, and a time stamp that detects a time stamp added to the encoded data generated by the encoding unit Detection means, zero-round detection means for detecting occurrence of zero rounds based on the count value of the time stamp detected by the time stamp detection means, and encoded data based on the time stamp detected by the time stamp detection means The presentation time stamp indicating the presentation time of the current time is generated, and when the 0 lap detection means detects the occurrence of 0 lap, 0 is displayed. The presentation time stamp generating means for correcting the generated presentation time stamp based on the bit length of the time stamp used by the zero-round detection means to detect the occurrence of the number of times, and the encoded data generated by the encoding means are packetized. And packet generating means for adding the presentation time stamp generated by the presentation time stamp generating means to the encoded data packetized by the packetizing means.

As described above, in the present invention, the 0-round detection means detects the occurrence of 0 rounds, and when the 0 rounds occur, the presentation time stamp corrected based on the bit length of the time stamp is obtained. Yes.
Therefore, according to the present invention, it is possible to provide a video encoding device capable of normally converting a local time stamp into a presentation time stamp even when 0 rounds occur.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a functional block diagram showing the configuration of a video encoding circuit according to the present invention, and this circuit is implemented in a video encoding device. The video encoding circuit includes an H.264 encoder 10 and an MPEG-2 Systems TS multiplexer 20. Although shown here as functional blocks, these configurations can also be realized by one DSP chip and its control program.

  The H.264 encoder 10 performs encoding processing according to the video compression method of ITU-T recommendation H.264 on video information of moving images, and generates H.264 elementary stream (ES) as encoded data. Is generated.

  The H.264 encoder 10 is based on an HRD (Hypothetical Reference Decoder) model as shown in FIG. This HRD model includes a CPB (Coded Picture Buffer) 1, a decoder 2, and a DPB (Decoded Picture Buffer) 3. CPB1 buffers the encoded data and outputs it to decoder 2. The data decoded by the decoder 2 is output after being buffered by the DPB 3.

  In the following description, the time when the encoded data of the nth frame is output from CPB1 is tr, n (n), and the time when the decoded data is output from DPB3 is to, dpb (n). explain. In DPB3, it is assumed that only time dpb_output_delay (n) is buffered.

  The MPEG-2 Systems TS multiplexer 20 packetizes video data such as the H.264 elementary stream, audio data, and other data into 188-byte TS (Transport Stream) packets, and multiplexes them. A port stream (TS) is generated. In the following description, the configuration related to the H.264 elementary stream will be described in detail.

  As shown in FIG. 3, the MPEG-2 Systems TS multiplexer 20 includes an ES (Elementary Stream) parsing unit 21, a 0-round determination unit 22, a PTS (Presentation Time Stamp) generation unit 23, and a PES. A (Packetized Elementary Stream) packet generator 24, a TS (Transport Stream) packet generator 25, and a multiplex switch 26 are provided.

  For example, the ES parsing unit 21 divides the H.264 elementary stream into frames and outputs the PES payload as a PES payload to the PES packet generation unit 24, and analyzes the components (syntax) of each PES payload, Information necessary for the time stamp conversion process in the generation unit 23 is extracted from the PES payload and notified to the PTS generation unit 23. Of the extracted information, the local time stamp is output to the 0-round determination unit 22.

The 0-round determination unit 22 compares the local time stamps of each frame detected by the ES parsing unit 21 between frames to determine whether or not 0 rounds have occurred in the local time stamp, and this determination result is used as the PTS. The data is output to the generation unit 23. Specific detection methods here, the time t _n indicated by the time stamp of a frame f _n, is subtracted from the frame f _{n + 1} time stamp indicates the time t _{n + 1} subsequent to the frame f _n, the subtraction result When the sign of is negative, it is determined that 0 rounds have occurred.

  The PTS generator 23 includes a normal processing unit 23a and a zero-round processing unit 23b. Both the normal processing means 23a and the 0-round processing means 23b generate a PTS (Presentation Time Stamp). However, if the 0-round determination unit 22 does not detect the occurrence of 0 rounds, the normal processing means 23a On the other hand, when PTS is generated and occurrence of 0 rounds is detected, PTS is generated by the 0 round processing means 23b.

The normal processing means 23a obtains the PTS based on the following expressions (1) and (2). Here, PTS corresponds to to, dpb (n) in the following equation (2). n indicates that the frame to be processed is the nth frame.

  In the above equation, tr, n (nb) is tr, n (n) obtained for the most recent IDR frame (nbth frame) as seen from the nth frame. In preparation for this, tr, n (nb) is held by the PTS generator 23. Specifically, the PTS generation unit 23 detects that tr, n (n) obtained by the PTS generation unit 23 is related to the IDR frame based on information notified from the ES parsing unit 21, and detects this tr, n (nb) is retained until at least processing for the next IDR frame is performed.

  In the above equations (1) and (2), tc represents the time resolution per clock. Further, cpb_removal_delay (n) corresponds to the value of the local time stamp, and a value detected by the ES parsing unit 21 from the PES payload is substituted. Similarly, tc uses a value detected from the PES payload by the ES parsing unit 21. Also for dpb_output_delay (n), the value detected from the PES payload by the ES parsing unit 21 is used.

  On the other hand, the 0-round processing means 23b obtains the time to, dpb (n) by the processing of the normal processing means 23a as described above, and considers the 0-round by taking the value obtained by adding the correction value δ to PTS. The generated value is generated and output to the PES packet generator 24.

  For example, the correction value δ is obtained as follows. The bit length of the local time stamp cpb_removal_delay (n−1) of the previous frame (n−1) is detected based on the information notified from the ES parsing unit 21, and the maximum time t_max (n− Find 1). A value obtained by subtracting the cpb_removal_delay (n-1) from the t_max (n-1) is set as a correction value δ. For this reason, the PTS generation unit 23 holds at least the above-mentioned information of one frame before the information notified from the ES parsing unit 21.

  The PES packet generation unit 24 generates a PES header into which the PTS obtained by the PTS generation unit 23 is inserted, adds this to the head of the PES payload output from the ES parsing unit 21, and generates a PES packet. .

  The TS packet generator 25 divides the PES packet into 184-byte TS (Transport Stream) payloads, adds a TS (Transport Stream) header to the head of each TS payload, and generates a TS (Transport Stream) packet.

  The TS packet generated by the TS packet generation unit 25 is multiplexed with audio data or the like converted into TS packets by another system (not shown) by the multiplexing switch 26 and output as a transport stream (TS). The

  As described above, in the video encoding device having the above-described configuration, the 0-round determination unit 22 determines whether or not the 0-round has occurred, and if the 0-round does not occur, the PTS generator 23 performs the normal processing unit. A PTS is generated by normal processing using 23a. On the other hand, when 0 rounds occur, the PTS generator 23 uses the 0 round processing means 23b to correct the PTS obtained by normal processing based on the bit length of the local time stamp of the previous frame. A value obtained by adding the value δ is set as PTS.

  Therefore, according to the video encoding device having the above-described configuration, even if 0 rounds occur by shortening the bit length of the local time stamp, the local time stamp can be normally converted to PTS. For this reason, the bit length of the local time stamp can be shortened, and the amount of transmission information can be reduced.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. Further, for example, a configuration in which some components are deleted from all the components shown in the embodiment is also conceivable. Furthermore, you may combine suitably the component described in different embodiment.

1 is a circuit block diagram showing a configuration of an embodiment of a video encoding circuit according to the present invention. The figure which shows the HRD model of the H.264 encoder of the video coding circuit shown in FIG. FIG. 2 is a circuit block diagram showing a configuration of an MPEG-2 Systems TS multiplexer of the video encoding circuit shown in FIG. 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... CPB, 2 ... Decoder, 3 ... DPB, 10 ... H.264 encoder, 20 ... MPEG-2 Systems TS multiplexer, 21 ... ES parse unit, 22 ... 0 round trip determination unit, 23 ... PTS generation unit, 23a ... Normal processing means, 23b... 0 round processing means, 24... PES packet generation section, 25... TS packet generation section, 26.

Claims (9)

In a video encoding circuit that encodes a moving image signal using a video compression method in which a local time stamp can be set with an arbitrary bit length,
Encoding means for encoding a moving image signal into encoded data in units of frames using the moving image compression method, and adding the local time stamp to the encoded data;
Local time stamp detecting means for detecting a local time stamp attached to the encoded data generated by the encoding means;
Based on the count value of the local time stamp detected by the local time stamp detecting means, 0 lap detecting means for detecting occurrence of 0 lap;
When the presentation time stamp indicating the presentation time of the encoded data is generated based on the local time stamp detected by the local time stamp detection means, and the zero lap detection means detects the occurrence of zero laps A presentation time stamp generating means for correcting the generated presentation time stamp based on the bit length of the local time stamp used by the zero turn detection means to detect the occurrence of the zero lap;
Packetizing means for packetizing the encoded data generated by the encoding means;
A video encoding circuit comprising: packet generation means for adding the presentation time stamp generated by the presentation time stamp generation means to the encoded data packetized by the packetization means.   2. The 0-round detection means detects occurrence of 0 rounds by comparing the count values of two consecutive local time stamps detected by the local timestamp detection means. Video encoding circuit.   The presenting time stamp generating means is configured to detect a time out of two local time stamps used by the zero lap detection means to detect the zero lap occurrence when the zero lap detection means detects the occurrence of the zero lap. The maximum count value represented by the bit length is obtained from the local time stamp preceding the local time stamp, and the generated presentation is based on a value obtained by subtracting the count value of the local time stamp preceding in time from the maximum count value. The video encoding circuit according to claim 2, wherein the time stamp is corrected. In a video encoding device that encodes a moving image signal using a video compression method in which a local time stamp can be set with an arbitrary bit length,
Encoding means for encoding a moving image signal into encoded data in units of frames using the moving image compression method, and adding the local time stamp to the encoded data;
Local time stamp detecting means for detecting a local time stamp attached to the encoded data generated by the encoding means;
Based on the count value of the local time stamp detected by the local time stamp detecting means, 0 lap detecting means for detecting occurrence of 0 lap;
When the presentation time stamp indicating the presentation time of the encoded data is generated based on the local time stamp detected by the local time stamp detection means, and the zero lap detection means detects the occurrence of zero laps A presentation time stamp generating means for correcting the generated presentation time stamp based on the bit length of the local time stamp used by the zero turn detection means to detect the occurrence of the zero lap;
Packetizing means for packetizing the encoded data generated by the encoding means;
A video encoding apparatus comprising: packet generation means for adding the presentation time stamp generated by the presentation time stamp generation means to the encoded data packetized by the packetization means.   5. The 0-round detection means detects occurrence of 0 rounds by comparing the count values of two consecutive local timestamps detected by the local timestamp detection means. Video encoding device.   The presenting time stamp generating means is configured to detect a time out of two local time stamps used by the zero lap detection means to detect the zero lap occurrence when the zero lap detection means detects the occurrence of the zero lap. The maximum count value represented by the bit length is obtained from the local time stamp preceding the local time stamp, and the generated presentation is based on a value obtained by subtracting the count value of the local time stamp preceding the time from the maximum count value. 6. The video encoding apparatus according to claim 5, wherein the time stamp is corrected. In a multiplexing circuit that packet-multiplexes encoded data of a moving image generated by a moving image compression method in which a local time stamp can be set with an arbitrary bit length, with other encoded data,
Local time stamp detecting means for detecting a local time stamp attached to the encoded data of the moving image;
Based on the count value of the local time stamp detected by the local time stamp detecting means, 0 lap detecting means for detecting occurrence of 0 lap;
When the presentation time stamp indicating the presentation time of the encoded data is generated based on the local time stamp detected by the local time stamp detection means, and the zero lap detection means detects the occurrence of zero laps A presentation time stamp generating means for correcting the generated presentation time stamp based on the bit length of the local time stamp used by the zero turn detection means to detect the occurrence of the zero lap;
Packetizing means for packetizing the encoded data generated by the encoding means;
A multiplexing circuit comprising: packet generation means for adding the presentation time stamp generated by the presentation time stamp generation means to the encoded data packetized by the packetization means.   8. The zero round detection unit detects occurrence of zero rounds by comparing the count values of two consecutive local time stamps detected by the local timestamp detection unit. Multiplexing circuit.   The presenting time stamp generating means is configured to detect a time out of two local time stamps used by the zero lap detection means to detect the zero lap occurrence when the zero lap detection means detects the occurrence of the zero lap. The maximum count value represented by the bit length is obtained from the local time stamp preceding the local time stamp, and the generated presentation is based on a value obtained by subtracting the count value of the local time stamp preceding in time from the maximum count value. The multiplexing circuit according to claim 8, wherein the time stamp is corrected.

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