[FFmpeg-user] AVStream time_base not getting set

[basteon]

hi,
you could try 601 for den and 12 for num.


On 28 June 2013 13:28, Zach Jacobs <zachjacobs at gmail.com> wrote:

> Hello,
>
> I am attempting to open an AVFormatContext for writing to a file but I do
> not think my AVStream time_base is getting set correctly when calling
> avformat_write_headers.
>
> Here is what I am doing:
>
> AVFormatContext* oF = (AVFormatContext*)outputFile.ToPointer();
> code = avformat_alloc_output_context2(&oF,null,null,outputPath);
>
> outputFile = new IntPtr(oF);
> if (code < 0)
>    throw new Exception("EncodingError: Could not open path " + outputPath);
>
> code = avio_open(&oF->pb, outputPath,AVIO_FLAG_WRITE);
>
> if (code < 0)
> {
>      string avError = EncoderUtilities.GetFFmpegErrorString(code);
>      throw new Exception("EncodingError: Couldn't connect to stream " +
> outputPath + ": " + avError);
> }
>
> AVCodec* vidCod = avcodec_find_encoder(AV_CODEC_ID_H264);
> if (videoCodec == null)
>     throw new Exception("FFMPEG Encoder Error: Codec Not Found");
>
> AVCodecContext* vidCodCon = avcodec_alloc_context3(vidCod);
> vidCodCon->bit_rate = encoderInfo.Settings.OutputVideoBitrate/8;
> vidCodCon->bit_rate_tolerance = encoderInfo.Settings.OutputVideoBitrate/8;
>
> vidCodCon->width = encoderInfo.Settings.OutputVideoWidth;
> vidCodCon->height = encoderInfo.Settings.OutputVideoHeight;
>
> vidCodCon->gop_size = encoderInfo.Settings.KeyFrameInterval;
> vidCodCon->max_b_frames = 0;
> vidCodCon->pix_fmt = AV_PIX_FMT_YUV420P;
>
> vidCodCon->flags |= CODEC_FLAG_GLOBAL_HEADER;
>
> vidCodCon->time_base.num = 1;
> vidCodCon->time_base.den = TIMEBASE_DENOMINATOR;  //30000
> vidCodCon->codec_type = AVMEDIA_TYPE_VIDEO;
> vidCodCon->codec_id = AV_CODEC_ID_H264;
>
> av_opt_set(vidCodCon->priv_data, "preset", "superfast", 0);
> av_opt_set(vidCodCon->priv_data, "profile", "main", 0x0001); //
> AV_OPT_SEARCH_CHILDREN
> av_opt_set(vidCodCon->priv_data, "crf", "22", 0);
>
> vidCodCon->rc_min_rate = bitrate/8;
> vidCodCon->rc_max_rate = bitrate/8;
> vidCodCon->rc_buffer_size = bitrate / 8;
>
> if (avcodec_open2(vidCodCon, vidCod, null) < 0)
>     throw new Exception("FFmpeg Encoder Error: could not open video
> codec");
>
> AVStream* vidStr = avformat_new_stream(outFile, vidCod);
>
> if (vidStr == null)
>     throw new Exception("Encoder Error: could not allocate video stream");
>
> vidStr->codec = (AVCodecContext*)av_malloc((uint)sizeof(AVCodecContext));
> EncoderUtilities.MemoryCopy(vidStr->codec, vidCodCon, (uint)sizeof
> (AVCodecContext));
>
> vidStr->codec->extradata =
> (byte*)av_malloc((uint)vidStr->codec->extradata_size);
> EncoderUtilities.MemoryCopy(vidStr->codec->extradata, vidCodCon->extradata,
> (uint)vidStr->codec->extradata_size);
>
> code = avformat_write_header(oF, null);
>
>
> I can verify that the vidStr->codec has the correct timebase.  No fcns
> return <0 error codes.  After I call avformat_write_header(), the
> videoStr.time_base doesn't get updated as indicated by the API here:
>     /**
>      * This is the fundamental unit of time (in seconds) in terms
>      * of which frame timestamps are represented.
>      *
>      * decoding: set by libavformat
>      * encoding: set by libavformat in avformat_write_header. The muxer may
> use the
>      * user-provided value of @ref AVCodecContext.time_base
> "codec->time_base"
>      * as a hint.
>      */
>     AVRational time_base;
>
> When running my program, Libx264 throws a "non-strictly-monotonic PTS"
> error.
>
> Any ideas on what could be going wrong?  Am I setting everything up
> correctly?  Thank you!
>
> Zach
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