[Libav-user] Decoding Problem (got_picture always return 0)

[Việt Hùng Nguyễn]

And before you send data to decoder, remember put 4 bytes header 0x00 0x00
0x00 0x01.

Hung, Nguyen Viet
On Mar 23, 2012 8:48 PM, "Việt Hùng Nguyễn" <hungtrodt5 at gmail.com> wrote:

> Hi, you should use CODEC_ID_H264, cause libx264 produces h.264 video
> stream and ffmpeg mpeg4 decoder can not decode h.264 video stream.
>
> Hung, Nguyen Viet
> On Mar 23, 2012 8:11 PM, "ZHAO Yinxia" <hydezhao at gmail.com> wrote:
>
>> Hi huanggh0108,
>>
>> I am sure I have no audio frame... While, I use libx264 to encode the
>> frames, and I am not sure I chose the right CODEC_ID for decoding.
>>
>> I use CODEC_ID_MPEG4. CODEC_ID_H264 looks more reasonable, but returns a
>> "no frame" error.
>>
>> 2012/3/23 huanggh0108 <huanggh0108 at sina.com>
>>
>>> **
>>> I guess the data may be audio frame, not video frame.  The data should
>>> be filtered before sending at the server end.
>>>
>>>
>>> 2012-03-23
>>> ------------------------------
>>>  huanggh0108
>>> ------------------------------
>>> *发件人：* Yinxia
>>> *发送时间：* 2012-03-23  00:52:01
>>> *收件人：* libav-user
>>> *抄送：*
>>> *主题：* [Libav-user] Decoding Problem (got_picture always return 0)
>>>   Hi dear all,
>>>
>>> I am a newbie to ffmpeg and I would like to decode the bitstream, which is
>>>
>>> encoded using libx264 at the server end and sent to client frame by frame.
>>>  I wrote a function decodeFrame to decode this bitstream frame by frame,
>>> this function is called in a loop, each time recieves a new frame:
>>>  void decodeFrame( int size, unsigned char *data)
>>> {
>>>  avpkt.size = size;
>>> avpkt.data = (uint8_t *)(data);
>>>  /*decode each frame*/
>>>  len = avcodec_decode_video2(c, picture, &got_picture, avpkt.size);
>>> if (len < 0) {
>>>  fprintf(stderr, "[avcodec][Err] Error while decoding frame %d\n",frame);
>>>  exit(1);
>>> }
>>>  if (got_picture) {
>>> printf("[avcodec] Saving frame %3d\n",frame);
>>>  fflush(stdout);
>>> _snprintf(buf, sizeof(buf), "/temp/video%d.pgm", frame); // not found
>>>
>>>  pgmSave(picture->data[0], picture->linesize[0], c->width, c->height, buf);
>>>  frame++;
>>> }
>>> }
>>>  I can successfully get the value of len, which is exactly the size of
>>> frame, however, *the value of *got_picture *is always 0. *Can anyone help
>>> me with this?
>>> *
>>> *
>>> PS. this is the init function of decoder.
>>>  void initDecoder()
>>> {
>>> avcodec_register_all();
>>>  av_init_packet(&avpkt);
>>> memset(inbuf + INBUF_SIZE, 0, FF_INPUT_BUFFER_PADDING_SIZE);
>>>  printf("[avcodec] Frame decoding initializing\n");
>>>  /*choose correct video decoder*/
>>>  codec = avcodec_find_decoder(CODEC_ID_MPEG4);
>>> if ( !codec ) {
>>> fprintf(stderr, "[avcodec][Err] codec not found!\n");
>>>  exit(1);
>>> }
>>>  c = avcodec_alloc_context3(codec);
>>>  picture = avcodec_alloc_frame();
>>>  if(codec->capabilities&CODEC_CAP_TRUNCATED)
>>>            c->flags|= CODEC_FLAG_TRUNCATED; /* we do not send complete
>>> frames */
>>>      /* open it */
>>>     if (avcodec_open2(c, codec, NULL) < 0) {
>>>         fprintf(stderr, "[avcodec][Err] could not open codec\n");
>>>         exit(1);
>>>     }
>>>  frame = 0;
>>>  }
>>>  Thank you very much!
>>> Yinxia
>>>  --
>>> View this message in context:
>>> http://libav-users.943685.n4.nabble.com/Decoding-Problem-got-picture-always-return-0-tp4496039p4496039.html
>>> Sent from the libav-users mailing list archive at Nabble.com.
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>>
>> _______________________________________________
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>>
>>
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