[lug] individual frames from AVI file?

Tkil tkil at scrye.com
Thu Jun 10 01:10:04 MDT 2004

>>>>> "Rodger" == Rodger Wilson <Wilson> writes:

Rodger> I think Canon uses something a little strange like jpeg for
Rodger> their movies.

Well, it's an MJPEG ("MJPG") stream inside a RIFF-style AVI container.
Which many tools seemed to recognize ("tcprobe", etc)... but decoding
those into frames seemed much harder.

And MJPEG is indeed different from MPEG; the latter uses full key /
inter / delta frames, with motion detection magic, etc.  I believe
MJPEG is much much simpler, which is why devices with less CPU power
prefer to encode video as MJPEG instead of even MPEG-1.

On top of being MJPEG and not MPEG, it seems that Canon digicams use
an unusual YUV coding method; it is likely still within the applicable
standard, but it is probable that it doesn't get as much testing as
more mainstream codings.  (Or so I infer from the fact that someone
had to issue a patch explicitly to support that coding format, and
someone else replied that it allowed them to decode Canon-created
MJPEG streams...)

Anyway, I eventually used "mplayer" to get individual frames out of
the AVI, various single-image viewers to find a likely loop, then
"convert" to create a single animated GIF out of the frames I liked.

Thanks for the reminder anyway.  :) This is exactly the sort of stupid
oversight I've lost whole nights to.

Thanks again,

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