Output black when I decode h264 720p with ffmpeg - ffmpeg

Question

First, sorry for my english. When I decode h264 720p in ardrone2.0 my output is black and I cant see anything.
I have try to change the value of pCodecCtx->pix_fmt = AV_PIX_FMT_BGR24; to pCodecCtx->pix_fmt = AV_PIX_FMT_YUV420P; and the value of pCodecCtxH264->pix_fmt = AV_PIX_FMT_BGR24; to pCodecCtxH264->pix_fmt = AV_PIX_FMT_YUV420P; but my program crash. What am I doing wrong?. Thank you, see part of my code:
av_register_all();
avcodec_register_all();
avformat_network_init();
// 1.2. Open video file
if(avformat_open_input(&pFormatCtx, drone_addr, NULL, NULL) != 0) {
mexPrintf("No conecct with Drone");
EndVideo();
return;
}
pCodec = avcodec_find_decoder(AV_CODEC_ID_H264);
pCodecCtx = avcodec_alloc_context3(pCodec);
pCodecCtx->pix_fmt = AV_PIX_FMT_BGR24;
pCodecCtx->skip_frame = AVDISCARD_DEFAULT;
pCodecCtx->error_concealment = FF_EC_GUESS_MVS | FF_EC_DEBLOCK;
pCodecCtx->err_recognition = AV_EF_CAREFUL;
pCodecCtx->skip_loop_filter = AVDISCARD_DEFAULT;
pCodecCtx->workaround_bugs = FF_BUG_AUTODETECT;
pCodecCtx->codec_type = AVMEDIA_TYPE_VIDEO;
pCodecCtx->codec_id = AV_CODEC_ID_H264;
pCodecCtx->skip_idct = AVDISCARD_DEFAULT;
pCodecCtx->width = 1280;
pCodecCtx->height = 720;
pCodecH264 = avcodec_find_decoder(AV_CODEC_ID_H264);
pCodecCtxH264 = avcodec_alloc_context3(pCodecH264);
pCodecCtxH264->pix_fmt = AV_PIX_FMT_BGR24;
pCodecCtxH264->skip_frame = AVDISCARD_DEFAULT;
pCodecCtxH264->error_concealment = FF_EC_GUESS_MVS | FF_EC_DEBLOCK;
pCodecCtxH264->err_recognition = AV_EF_CAREFUL;
pCodecCtxH264->skip_loop_filter = AVDISCARD_DEFAULT;
pCodecCtxH264->workaround_bugs = FF_BUG_AUTODETECT;
pCodecCtxH264->codec_type = AVMEDIA_TYPE_VIDEO;
pCodecCtxH264->codec_id = AV_CODEC_ID_H264;
pCodecCtxH264->skip_idct = AVDISCARD_DEFAULT;
if(avcodec_open2(pCodecCtxH264, pCodecH264, &optionsDict) < 0)
{
mexPrintf("Error opening H264 codec");
return ;
}
pFrame_BGR24 = av_frame_alloc();
if(pFrame_BGR24 == NULL) {
mexPrintf("Could not allocate pFrame_BGR24\n");
return ;
}
// Determine required buffer size and allocate buffer
buffer_BGR24 =
(uint8_t *)av_mallocz(av_image_get_buffer_size(AV_PIX_FMT_BGR24,
pCodecCtx->width, ((pCodecCtx->height == 720) ? 720 : pCodecCtx->height) *
sizeof(uint8_t)*3,1));
// Assign buffer to image planes
av_image_fill_arrays(pFrame_BGR24->data, pFrame_BGR24->linesize,
buffer_BGR24,AV_PIX_FMT_BGR24, pCodecCtx->width, pCodecCtx->height,1);
// format conversion context
pConvertCtx_BGR24 = sws_getContext(pCodecCtx->width, pCodecCtx->height,
pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_BGR24,
SWS_BILINEAR | SWS_ACCURATE_RND, 0, 0, 0);
// 1.6. get video frames
pFrame = av_frame_alloc();
av_init_packet(&packet);
packet.data = NULL;
packet.size = 0;
}
//Captura un frame
void video::capture(mxArray *plhs[]) {
if(av_read_frame(pFormatCtx, &packet) < 0){
mexPrintf("Error al leer frame");
return;
}
do {
do {
rest = avcodec_send_packet(pCodecCtxH264, &packet);
} while(rest == AVERROR(EAGAIN));
if(rest == AVERROR_EOF || rest == AVERROR(EINVAL)) {
printf("AVERROR(EAGAIN): %d, AVERROR_EOF: %d,
AVERROR(EINVAL): %d\n", AVERROR(EAGAIN), AVERROR_EOF,
AVERROR(EINVAL));
printf("fe_read_frame: Frame getting error (%d)!\n", rest);
return;
}
rest = avcodec_receive_frame(pCodecCtxH264, pFrame);
} while(rest == AVERROR(EAGAIN));
if(rest == AVERROR_EOF || rest == AVERROR(EINVAL)) {
// An error or EOF occured,index break out and return what
// we have so far.
printf("AVERROR(EAGAIN): %d, AVERROR_EOF: %d, AVERROR(EINVAL): %d\n",
AVERROR(EAGAIN), AVERROR_EOF, AVERROR(EINVAL));
printf("fe_read_frame: EOF or some othere decoding error (%d)!\n",
rest);
return;
}
// 2.1.1. convert frame to GRAYSCALE [or BGR] for OpenCV
sws_scale(pConvertCtx_BGR24, (const uint8_t* const*)pFrame->data,
pFrame->linesize, 0,pCodecCtx->height, pFrame_BGR24->data,
pFrame_BGR24->linesize);
//}
av_packet_unref(&packet);
av_init_packet(&packet);
mwSize dims[] = {(pCodecCtx->width)*((pCodecCtx->height == 720) ? 720 :
pCodecCtx->height)*sizeof(uint8_t)*3};
plhs[0] = mxCreateNumericArray(1,dims,mxUINT8_CLASS, mxREAL);
//plhs[0]=mxCreateDoubleMatrix(pCodecCtx->height,pCodecCtx-
>width,mxREAL);
point=mxGetPr(plhs[0]);
memcpy(point, pFrame_BGR24->data[0],(pCodecCtx->width)*(pCodecCtx-
>height)*sizeof(uint8_t)*3);
}

Answer 1

Go to debugger and see your memcpy. I am not sure if it works for all dimensions that you want. Also, there may be more memory problems. For example, try to see what is the value of buffer_BGR24 and pFrame. I bet that sometimes, they do not return right values. Check them out in the code.