[Libav-user] got_picture_ptr of avcodec_decode_video2 always returns 0 for a particular MTS file
Simon Daniels
simondaniels23 at gmail.com
Tue Feb 7 07:14:25 CET 2012
I updated all the deprecated functions and I'm still having the same
problem.
On Mon, Feb 6, 2012 at 9:47 PM, Simon Daniels <simondaniels23 at gmail.com>wrote:
> Hi Andrey,
>
> Thanks for the help!
>
> 1. Lib versions: Using the shared library and my code below, I tried 0.8.3
> (PC) and 08d2cee4 (Mac) and could not scan the file. However, I tried the
> static executable of 0.8 and 0.10 on Mac and I *could* transcode it to MP4.
>
> 2. Link to video (it's almost 2gb):
> http://dl.dropbox.com/u/28441949/00793.MTS
>
> 3. Simplified, but compilable source code:
>
> int Scan(const char *inputfile)
> {
>
> totalFrames = 0;
> frameLocation = 0;
>
> AVFormatContext *pFormatCtx;
> unsigned int i, videoStream;
> AVCodecContext *pCodecCtx;
> AVCodec *pCodec;
> AVFrame *pFrame;
> AVFrame *pFrameYUV;
> int numBytes;
> uint8_t *buffer;
>
> clock_t start = clock();
>
> // Register all formats and codecs
> av_register_all();
>
> // Open video file
> if(av_open_input_file(&pFormatCtx, inputfile, NULL, 0, NULL)!=0)
> {
> return -1; // Couldn't open file
> }
>
> // Retrieve stream information
> if(av_find_stream_info(pFormatCtx)<0)
> {
> return -2; // Couldn't find stream information
> }
>
> // Dump information about file onto standard error
> dump_format(pFormatCtx, 0, inputfile, false);
>
> // Find the first video stream
> videoStream=-1;
> for(i=0; i<pFormatCtx->nb_streams; i++)
> {
> if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
> {
> videoStream=i;
> break;
> }
> }
> if(videoStream==-1)
> {
> return -3; // Didn't find a video stream
> }
>
> // Get a pointer to the codec context for the video stream
> pCodecCtx = pFormatCtx->streams[videoStream]->codec;
>
> // get duration
> double duration = double(pFormatCtx->duration) / AV_TIME_BASE;
> cout << "Video duration: " << duration << std::endl;
>
> // Find the decoder for the video stream
> pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
> if(pCodec==NULL)
> {
> return -4; // Codec not found
> }
>
> // Inform the codec that we can handle truncated bitstreams -- i.e.,
> // bitstreams where frame boundaries can fall in the middle of packets
> if(pCodec->capabilities & CODEC_CAP_TRUNCATED)
> pCodecCtx->flags|=CODEC_FLAG_TRUNCATED;
>
> // Open codec
> if(avcodec_open(pCodecCtx, pCodec)<0)
> {
> return -5; // Could not open codec
> }
>
> std::cout << "Using codec: " << pCodec->name << std::endl;
>
>
> // Allocate video frame
> pFrame=avcodec_alloc_frame();
>
> // Allocate an AVFrame structure
> pFrameYUV=avcodec_alloc_frame();
> if(pFrameYUV==NULL)
> {
> return -6;
>
> }
>
> // Determine required buffer size and allocate buffer
> // originally: PIX_FMT_RGB24
> numBytes=avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width,
> pCodecCtx->height);
> buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
>
> // Assign appropriate parts of buffer to image planes in pFrameRGB
> // originally: PIX_FMT_RGB24
> avpicture_fill((AVPicture *)pFrameYUV, buffer, PIX_FMT_YUV420P,
> pCodecCtx->width, pCodecCtx->height);
>
> totalFrames = pFormatCtx->streams[videoStream]->nb_frames;
> printf("Frames: %d\n", totalFrames);
>
> AVPacket packet;
> int isFrameFinished = 0;
>
> int pixelScanCount = 0;
>
> std::cout << "videoWidth = " << pCodecCtx->width << std::endl;
> std::cout << "videoHeight = " << pCodecCtx->height << std::endl;
>
>
> while (av_read_frame(pFormatCtx, &packet) >= 0)
> {
>
> // Is this a packet from the video stream?
> if (packet.stream_index == videoStream &&
> frameLocation++ % frameSkip == 0)
> {
> // Decode video frame
>
> avcodec_decode_video2(pCodecCtx, pFrame, &isFrameFinished,
> &packet);
>
>
> // Did we get a video frame?
> if (isFrameFinished) {
>
> // SCANNING GOES HERE
> pixelScanCount = 0;
>
> for (int y = 0; y < pCodecCtx->height; y++)
> {
> uint8_t *p = pFrame->data[0] + y *
> pFrame->linesize[0]; // this gets Y' in YUV
>
> for (int x = 0; x < pCodecCtx->width; x++)
> {
>
> pixelScanCount++;
>
> //printf("Frame %d at %d, %d has Y'=%d\n",
> frameLocation, x, y, p[x]);
> }
>
> }
>
> av_free_packet(&packet);
>
> }
> else // frame isn't finished. not sure why we'd hit this
> {
> av_free_packet(&packet);
> }
>
>
> }
>
> }
>
> delete [] buffer;
> av_free(pFrameYUV);
>
>
> // Free the YUV frame
> av_free(pFrame);
>
> // Close the codec
> avcodec_close(pCodecCtx);
>
> // Close the video file
> av_close_input_file(pFormatCtx);
> }
>
>
> 4. When I enabled av_log_set_level(AV_LOG_DEBUG) in my app, I saw several
> of these:
> [h264 @ 09FC0940] Frame num gap 10 8
> [h264 @ 09FC0940] Frame num gap 15 12
> [h264 @ 09FC0940] Frame num gap 15 13
> [h264 @ 09FC0940] Frame num gap 20 17
> ...
>
>
> So considering the fact that the command-line utility was able to
> transcode, I'm assuming there's something wrong in my code. I've seen some
> warnings for deprecated functions so maybe that's my problem?
>
> Thanks!
>
> Simon
>
>
>
>
>
>
> On Mon, Feb 6, 2012 at 2:56 AM, Andrey Utkin <
> andrey.krieger.utkin at gmail.com> wrote:
>
>> Please help us help you - provide
>> - version of libs you use
>> - compilable minimized source code of your app
>> - this sample file
>>
>> BTW, did you try to transcode it with ffmpeg command-line utility? If
>> it also fails, please provide its full output with -loglevel debug
>> BTW2 try to av_log_set_level(AV_LOG_DEBUG); in your app - maybe you'll
>> see useful messages on stderr.
>>
>>
>> --
>> Andrey Utkin
>> _______________________________________________
>> Libav-user mailing list
>> Libav-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/libav-user
>>
>
>
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