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Le 15/10/2012 11:26, Chandranath Bhattacharyya a écrit :<br>
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<p class="MsoNormal">Hi All,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I downloaded windows ffmpeg build from <a
moz-do-not-send="true"
href="http://ffmpeg.zeranoe.com/builds/">http://ffmpeg.zeranoe.com/builds/</a>.
The build downloaded is
ffmpeg-20121009-git-f3f35f7-win32-shared.7z &
ffmpeg-20121009-git-f3f35f7-win32-dev.7z.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I built “examples/demuxing.c” using Visual
Studio 10 on windows. However, it’s not working. When invoked
with command line: <exename> output.mp4, it’s exiting
with the following errors:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">[mp4 @ 00582ea0] Encoder did not produce
proper pts, making some up.<o:p></o:p></p>
<p class="MsoNormal">[mp4 @ 00582ea0] pts (0) < dts (1) in
stream 0<o:p></o:p></p>
<p class="MsoNormal">Error while writing video frame<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I figured out that
av_interleaved_write_frame is failing because a call to
avcodec_encode_video2 is not changing
AVCodecContext::coded_frames->pts. It’s always 0, and hence
AVPacket.pts is 0. However the call to avcodec_encode_video2
is increasing the AVPacket.dts value from -2, -1, 0, 1. So in
4<sup>th</sup> call to av_interleaved_write_frame,
AVPacket.pts < AVPacket.dts causing the issue.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I made some code changes to ensure that pts
> dts, and then the file was written. However when opened
in Windows Media Player Classic, the file is showing a frame
rate of 12800. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I was using following. Modified
STREAM_DURATION to 10.0 from 200.0.<o:p></o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-size:9.5pt;font-family:Consolas;color:blue">#define</span><span
style="font-size:9.5pt;font-family:Consolas">
STREAM_DURATION 10.0<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-size:9.5pt;font-family:Consolas;color:blue">#define</span><span
style="font-size:9.5pt;font-family:Consolas">
STREAM_FRAME_RATE 25 <span style="color:green">/* 25
images/s */</span><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-size:9.5pt;font-family:Consolas;color:blue">#define</span><span
style="font-size:9.5pt;font-family:Consolas">
STREAM_NB_FRAMES ((<span style="color:blue">int</span>)(STREAM_DURATION
* STREAM_FRAME_RATE))<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-size:9.5pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none">With these
parameters,<span style="font-size:9.5pt;font-family:Consolas">
AVStream::codec->time_base = { num: 1, den: 25}, </span>but
just after call to<span
style="font-size:9.5pt;font-family:Consolas">
avformat_write_header, the AVStream::time_base = { num: 1,
den: 12800 }.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-size:9.5pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none">What’s going
wrong?<span style="font-size:9.5pt;font-family:Consolas">
AVStream::time_base.den = 12800; </span>seems to be wrong
data. Other than fixing some compilation errors, I did not
modify anything else in examples/demuxing.c.<o:p></o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-size:9.5pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal">Regards,<o:p></o:p></p>
<p class="MsoNormal">Chandranath<o:p></o:p></p>
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<br>
<br>
It seems i've got the same troubles since the 3 last zeranoe
packages. Previous ones were ok, but last 3 gives 12800 fps frame
for .mp4 rate and i've got some others troubles like that with other
encoders / containers...<br>
So i'm very interested in an answer to this question too !<br>
And as a bonus question : Should be set .pts for each frame to a
correct value for the encoder and for the container or can we keep
AV_NOPTS_VALUE ?<br>
<br>
regards<br>
<br>
Stephane<br>
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