[Bug 669164] theoraparse asserts about frame >= keyframe again

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=669164
  GStreamer | gst-plugins-base | 0.10.x

Vincent Penquerc'h <vincent.penquerch> changed:

           What    |Removed                     |Added
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                 CC|                            |vincent.penquerch at collabora
                   |                            |.co.uk

--- Comment #1 from Vincent Penquerc'h <vincent.penquerch at collabora.co.uk> 2012-02-01 13:50:27 UTC ---
It looks like the culprit is oggdemux, not theoraparse.
I *think* what's happening is that oggdemux places "interpolated" granpos
values on outgoing packets, and syncs when it sees an actual granpos. When a
page contains several packets, with one of these packets being a keyframe, and
where the number of frames comes close to the max keyframe distance (in this
file, a granshift of 5 means only 32 frames), the interpolated granpos may
violate that max distance (and wrap the "distance since last keyframe" part of
the granpos).

See dump from oggz validate showing this. Last known granpos is 398|23, max
granpos without needing an intervening keyframe would be 398|31. 422|8 is the
true granpos, but simple interpolation makes it an invalid 398|32, which is
equivalent to 398|0.

I guess the right fix is to detect keyframes, and bump/reset granpos
accordingly when interpolating.

00:00:17.458: serialno 1602069339, granulepos 398|21, packetno 421: 20.003 kB
00:00:17.500: serialno 1602069339, granulepos 398|22, packetno 422: 17.324 kB
00:00:17.541: serialno 1602069339, calc. gpos 398|23, packetno 423: 21.417 kB
00:00:17.583: serialno 1602069339, calc. gpos 422|0, packetno 424: 95 bytes
00:00:17.625: serialno 1602069339, calc. gpos 422|1, packetno 425: 0 bytes
00:00:17.666: serialno 1602069339, calc. gpos 422|2, packetno 426: 0 bytes
00:00:17.708: serialno 1602069339, calc. gpos 422|3, packetno 427: 0 bytes
00:00:17.750: serialno 1602069339, calc. gpos 422|4, packetno 428: 0 bytes
00:00:17.791: serialno 1602069339, calc. gpos 422|5, packetno 429: 0 bytes
00:00:17.833: serialno 1602069339, calc. gpos 422|6, packetno 430: 0 bytes
00:00:17.875: serialno 1602069339, calc. gpos 422|7, packetno 431: 0 bytes
00:00:17.916: serialno 1602069339, calc. gpos 422|8, packetno 432: 0 bytes
00:00:17.958: serialno 1602069339, calc. gpos 422|9, packetno 433: 0 bytes
00:00:18.000: serialno 1602069339, calc. gpos 422|10, packetno 434: 0 bytes
00:00:18.041: serialno 1602069339, calc. gpos 422|11, packetno 435: 0 bytes
00:00:18.083: serialno 1602069339, calc. gpos 422|12, packetno 436: 0 bytes
00:00:18.125: serialno 1602069339, calc. gpos 422|13, packetno 437: 0 bytes
00:00:18.166: serialno 1602069339, granulepos 422|14, packetno 438: 1.042 kB

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