Hi !
I'm working on a project that generates a kind of CBR video file and I want to
reproduce the same following command line in code :
ffmpeg -i videoFile.ts -qmin 10 -qmax 51 -vcodec libx264 -vb 300k -acodec
libfaac -ab 64k videoFile.mp4
It generates correctly a video file with about 300k bit / s for the video and
64k bit / s for the audio = 364 kb/s.
But when I'm trying to do the same thing by sing fmpeg library in C. It never
creates a videoFile with the bitrate set.
Here is a sample of my code, I think that some initialisations are missing ...
AVOutputFormat * pAVOutputFormat =
::guess_format(NULL, wFilesOut[i].strFileOut, NULL);
wFilesOut[i].pAVFormatCtxW =
::av_alloc_format_context();
AVFormatContext* pAVFormatCtxW =
wFilesOut[i].pAVFormatCtxW;
pAVFormatCtxW->oformat = pAVOutputFormat;
strcpy(pAVFormatCtxW->filename,
wFilesOut[i].strFileOut);
pAVFormatCtxW->ctx_flags = AVFMTCTX_NOHEADER;
pAVFormatCtxW->oformat->flags |=
AVFMT_GLOBALHEADER;
// add stream video
AVStream* pAVStream =
::av_new_stream(pAVFormatCtxW, pAVFormatCtxW->nb_streams);
avcodec_get_context_defaults2(pAVStream->codec,
AVMEDIA_TYPE_VIDEO);
pAVStream->codec->codec_id = CODEC_ID_H264;
pAVStream->codec->codec_type = CODEC_TYPE_VIDEO;
AVCodecContext * pAVCodecContext =
pAVStream->codec;
pAVCodecContext->width = srcWidth;
pAVCodecContext->height = srcHeight;
pAVCodecContext->time_base.num = 1;
pAVCodecContext->time_base.den = 25;
pAVCodecContext->bit_rate = video_bitrate;
pAVCodecContext->pix_fmt = PIX_FMT_YUV420P;
pAVCodecContext->strict_std_compliance = -2;
pAVCodecContext->flags |=
CODEC_FLAG_GLOBAL_HEADER;
pAVCodecContext->qmin = qmin;
pAVCodecContext->qmax = qmax;
pAVCodecContext->gop_size = gop_size;
pAVCodecContext->bit_rate_tolerance = 0;
AVCodec* pAVCodecVideo =
::avcodec_find_encoder(pAVStream->codec->codec_id);
int nRes = avcodec_open(pAVStream->codec,
pAVCodecVideo);
if (nRes < 0)
{
cerr<<"ERROR : avcodec_open
failed for video"<<endl;
return nRes;
}
// Add stream audio
pAVStream = ::av_new_stream(pAVFormatCtxW,
audio_channel);
avcodec_get_context_defaults2(pAVStream->codec,
AVMEDIA_TYPE_AUDIO);
pAVStream->codec->codec_id = CODEC_ID_AAC;
pAVStream->codec->codec_type = CODEC_TYPE_AUDIO;
pAVCodecContext = pAVStream->codec;
pAVCodecContext->channels = audio_channel;
pAVCodecContext->sample_rate = audio_sample_rate;
pAVCodecContext->bit_rate = audio_bitrate;
pAVCodecContext->channels = audio_channel;
pAVCodecContext->sample_rate = srcAF;
pAVCodecContext->flags |=
CODEC_FLAG_GLOBAL_HEADER;
AVCodec* pAVCodecAudio =
::avcodec_find_encoder(pAVStream->codec->codec_id);
//AVCodec* pAVCodecAudio =
::avcodec_find_encoder_by_name("libfaac");
pAVCodecContext->sample_fmt =
pAVCodecAudio->sample_fmts[0];
nRes = avcodec_open(pAVStream->codec,
pAVCodecAudio);
I thought :
pAVCodecContext->bit_rate = video_bitrate;
pAVCodecContext->qmin = qmin;
pAVCodecContext->qmax = qmax;
and
pAVCodecContext->bit_rate = audio_bitrate;
pAVCodecContext->qmin = qmin;
pAVCodecContext->qmax = qmax;
could solved the issue, but no, it simply generates a kind of CBR does not
depend on video or audio bitrate set.
Does somebody know why?
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