[FFmpeg-user] Remux doubts

[Austin Einter]

Hi All
I am new to FFmpeg.
But I am really excited to learn more about it.

I tried remuxing example as a first step.

I have taken remux example available at
http://ffmpeg.org/doxygen/trunk/doc_2examples_2remuxing_8c-example.html.

I compiled andlinked to ffmpeg .so files.
Everything went fine.

Now I downloaded a webm file (small.webm).
It contains vp8 and vorbis frames.

I did remux it and output file is remuxed.webm

I can play the remuxed webm file.

So far so good.

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Now  I wanted to remux a webm file that contains vp8 and opus frames.
I could not get such file in internet.

So I converted small.webm file to another file say output.webm that
contains vp8 and opus frames using below command.

*./ffmpeg -i small.webm -c:v libvpx -c:a libopus -qmin 0 -qmax 20
output.webm*

I opened output.webm in a mozilla browser and I am able to play it. Looks
everything fine here.

Then I did remux of output.webm and say resultant file is remuxed.webm.

If I try to pay remuxed.webm in mozilla browser, it does not play.
It gives an error "Video can't be played because the file is corrupt".

Can somebody help me to understand when I remux vp8/vorbis file it works,
and when I remux vp8/opus file it does not work using the example at
http://ffmpeg.org/doxygen/trunk/doc_2examples_2remuxing_8c-example.html.

I am using ffmpeg 2.7.1 version.

Thanks
Austin