Thanks Matthew.
That all helped, but I am still finding that if I do not set the pts before
my call to avcodec_encode_video I keep getting "non-strictly-monotonic PTS"
warning messages.
Do you not set the pts value on your AVFrame* before encoding?
Regards,
Zac Shenker
On Sat, Nov 5, 2011 at 3:16 AM, Matthew Einhorn <moiein2...@gmail.com>wrote:
> On Fri, Nov 4, 2011 at 2:40 AM, Zac Shenker <z...@zacshenker.com> wrote:
> > Hi,
> > I have started working on some code based on the decoding_encoding.c
> sample
> > file to encode the test pattern as h.264 video.
> > The settings I am using on my AVCodecContext is as follows:
> > c->width = 352;
> > c->height = 288;
> > c->time_base.num = 1;
> > c->time_base.den = 25;
> > c->pix_fmt = PIX_FMT_YUV420P;
> > c->gop_size = 1;
> > if(codec_id == CODEC_ID_H264)
> >
> > av_opt_set(c->priv_data, "preset", "slow", 0);
> >
> > I am having a number of issues:
> > 1) Even when I set the AVFrame->pts to AVS_NOPTS_VALUE, I still get
> > "non-strictly-monotonic PTS" warning messages. How should I be setting
> the
> > PTS value?
>
> See my code below. I don't set the pts or anything else in the frame
> other than copying the image data to the picture.
>
> > 2) For the first 13 frames my call to avcodec_encode_video returns a
> size of
> > 0, should this be happening?
> Yes, because it needs to buffer a couple of frames so it can calculate
> best compression.
>
> > 3) The output file that gets written does not seem to have a
> duration(using
> > ffprobe or VLC to check)
>
> Maybe you have to write the header and trailer before and after the
> video is written. I.e. avformat_write_header(m_pFormatCtx, NULL) and
> av_write_trailer(m_pFormatCtx);
>
> > So far to figure out how things work I have been searching through the
> > ffmpeg & x264 source, is there any up-to-date examples of doing h264
> video
> > encoding (no audio) anywhere?
>
> Look in ffmpeg.c and ffplay.c
>
>
>
> Here's how my code looks:
> if (m_pFormatCtx->oformat->flags & AVFMT_RAWPICTURE)
> {
> /* raw video case. The API will change slightly in the near
> future for that. Latency won't happen here. */
> AVPacket sPkt;
> av_init_packet(&sPkt);
>
> sPkt.flags |= AV_PKT_FLAG_KEY;
> sPkt.stream_index= m_pAVStream->index;
> sPkt.data= (unsigned char *)m_pAVFrame;
> sPkt.size= sizeof(AVPicture);
>
> nRes = av_interleaved_write_frame(m_pFormatCtx, &sPkt);
> } else
> {
> /* Encode the image, if flushing pass null frame. */
> nTemp = avcodec_encode_video(pCodecCtx, m_auchVideoOutBuf,
> m_nBuffer,
> auchBuffer?m_pAVFrame:NULL);
> /* If zero size, it means the image was buffered and will
> need to be
> flushed later. */
> if (nTemp > 0)
> {
> AVPacket sPkt;
> av_init_packet(&sPkt);
>
> // Save pts of frame
> if (pCodecCtx->coded_frame &&
> pCodecCtx->coded_frame->pts != AV_NOPTS_VALUE)
> sPkt.pts=
> av_rescale_q(pCodecCtx->coded_frame->pts,
> pCodecCtx->time_base, m_pAVStream->time_base);
> if(sPkt.pts == AV_NOPTS_VALUE && sPkt.dts ==
> AV_NOPTS_VALUE &&
> !(m_pFormatCtx->oformat->flags & AVFMT_NOTIMESTAMPS))
> sPkt.dts= 0;
>
> // Is it a key frame?
> if(pCodecCtx->coded_frame &&
> pCodecCtx->coded_frame->key_frame)
> sPkt.flags |= AV_PKT_FLAG_KEY;
> sPkt.stream_index= m_pAVStream->index;
> sPkt.data= m_auchVideoOutBuf;
> sPkt.size= nTemp;
> /* Write the compressed frame in the media file */
> nRes = av_interleaved_write_frame(m_pFormatCtx,
> &sPkt);
> } else
> {
> nRes = nTemp; // If zero it's ok, if none zero it
> means error.
> if (!auchBuffer) // Either way, no more
> frames to flush, if flushing
> m_bDone= true;
> }
> }
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