[theora] macro block artifacts of ogv file converted from mpeg(libthusnelda I 20090527)

Gregory Maxwell gmaxwell at gmail.com
Fri Jun 5 14:54:35 PDT 2009

On Fri, Jun 5, 2009 at 5:07 PM, Orton AKINCI aka .-_-.
<ortonak at yahoo.com> wrote:
> hi,
> there is a problem when i convert some mpeg files to ogv with libthusnelda I
> 20090527... i don't know it this helps you but i am sending information
> about it...

This appears to be an ffmpeg problem.

If I use ffplay from ffmpeg SVN-r18213 to play
02_mpeg_converted_from_original_avi.mpg I see the flashing block in
the lower left corner.

Transcoding the file using ffmpeg2theora-0.24-thusnelda.linux32.bin
gives the same result in the transcoded output, which is unsurprising
because it uses a recent FFMPEG for decoding.

I will report this to the ffmpeg developers.

The reason you don't see it with other older converters must be
because they are using a different version of ffmpeg for decode.

Thank you for the detailed report which allowed me to quickly exclude
many possible causes.

In the future you may want to use zip or tar for sending files like
this, because unrar is not free software many Linux distributions do
not ship it and developers on these platforms may need to undertake
extra effort to decode your archive.

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