[Bug 732631] Missing frames when encoding 16x16 video to MPEG4/MPEG2/H264

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=732631
  GStreamer | gst-libav | git

--- Comment #6 from Vincent Penquerc'h <vincent.penquerch at collabora.co.uk> 2014-07-03 12:05:18 UTC ---
According to http://dvd.sourceforge.net/dvdinfo/mpeghdrs.html, it seems the
picture header can be not only variable size, but of any size (at least if
crafted):

> additionally if the next bit is "1" (extra_bit_picture) it is followed by 8
> bits of "extra" data (discarded by decoders). This continues until a "0" bit
> is encountered. 

So for at least one case, we can't seem to have a high bound on the amount of
data that's present in the buffer prior to encoding a MB.

A middle ground would be to allocate some reasonably sized extra space that
should be enough in most cases (hopefully all reasonable ones). In the case of
such very large picture headers, encoding would still fail as it does now, but
cases like that 16x16 frame would pass.

Opinions ?

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