incorrect dts when encoding in ffmpeg
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YIRAN LI
Sep 5, 2013, 7:53:10 AM9/5/13
to webm-d...@webmproject.org
Hi friend,
I'm writing an application using ffmpeg libs on Windows (with --enable-libvpx).
Today I found something strange. In this application we call avcodec_encode_video2 first to get a AVPacket instance and write this packet into file with av_write_frame
I found that the pst values of returned packet is correct, they are 1, 2, 3, 4 .... (in input video stream time base). but dts values are always 0. I transferred the pts values to corresponding values (in output video stream time base) and keep 0 for dts. Then the webm files generated in this way can't be played correctly in ffplay (reported warnings of 0 DTS).
If I set all dts values to AV_NOPTS_VALUE, then the output video is perfect.
In fact I found that if use avcodec_encode_video to encode, then dts are AV_NOPTS_VALUE.
I'm building from latest libvpx code, could anyone help to check if it's a libvpx bug?
Great thanks!
James Zern
Sep 10, 2013, 1:38:42 AM9/10/13
to WebM Discussion
On Thu, Sep 5, 2013 at 4:53 AM, YIRAN LI <mrfun...@gmail.com> wrote:
> Hi friend,
>
> I'm writing an application using ffmpeg libs on Windows (with
> --enable-libvpx).
>
> Today I found something strange. In this application we call
> avcodec_encode_video2 first to get a AVPacket instance and write this packet
> into file with av_write_frame
>
> I found that the pst values of returned packet is correct, they are 1, 2, 3,
> 4 .... (in input video stream time base). but dts values are always 0. I
> transferred the pts values to corresponding values (in output video stream
> time base) and keep 0 for dts. Then the webm files generated in this way
> can't be played correctly in ffplay (reported warnings of 0 DTS).
These values are both set in the wrapper, libvpxenc.c [1], to the same
> Hi friend,
>
> I'm writing an application using ffmpeg libs on Windows (with
> --enable-libvpx).
>
> Today I found something strange. In this application we call
> avcodec_encode_video2 first to get a AVPacket instance and write this packet
> into file with av_write_frame
>
> I found that the pst values of returned packet is correct, they are 1, 2, 3,
> 4 .... (in input video stream time base). but dts values are always 0. I
> transferred the pts values to corresponding values (in output video stream
> time base) and keep 0 for dts. Then the webm files generated in this way
> can't be played correctly in ffplay (reported warnings of 0 DTS).
value. The wrapper has always forwarded the pts from the input frame.
>
> If I set all dts values to AV_NOPTS_VALUE, then the output video is perfect.
>
> In fact I found that if use avcodec_encode_video to encode, then dts are
> AV_NOPTS_VALUE.
>
> I'm building from latest libvpx code, could anyone help to check if it's a
> libvpx bug?
>
> Great thanks!
>
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