[PD] Codecs in Gem (again!) & ffmpeg

B. Bogart ben at ekran.org
Mon Aug 29 17:23:07 CEST 2005

Hello all, sorry for the cross-posting,

Back to the old codec issue here. I was hapiliy working with photo-jpg
compressed quicktime files for the last couple years. Now I'm working on
an installation that I'm aiming to make using only open-source software.

My "orginal" footage is a sequence of 300,000 jpeg frames (80% quality)
And all I need is a video file that matches the jpg quality of the
frames, and most importantly is seekable and loadable in Gem.

So what I want to do is create a quicktime file, using photo-jpeg as the
codec. Simple eh? hmmm.

My first try was:

ffmpeg -i %d.jpg -sameq -vcodec ljpeg output.mov

Which created the file fine (where, FYI, quicktime pro died miserably)
but was very big (which is ok) but I could not get vlc,mplayer,totem to
load it. ffmpeg printed something about "MS style codec tag" when
creating the file. so I also tried:

ffmpeg -i %d.jpg -sameq -vcodec mjpeg output.mov

which did about the same thing, so I gave up on quicktime and tried a
couple AVIs:

ffmpeg -i %d.jpg -sameq -vcodec mjpeg output.avi
ffmpeg -i %d.jpg -sameq -vcodec ljpeg output.avi

A little better, many of my Gem decoders loaded the file, but not a
single one was able to make it seekable, I tried all the decoders... all
return -1 frames.

So right now I'm building a mpeg2 to try out, though I know decoding is
going to be less efficient.

So my final questions are:

1. What codec should I use for 300,000 frames (14GB or so) and is well
suited to build from jpg frames? What container?

2. How can I create the [answer to #1] using ffmpeg or some other linux
land app?

Thank you!

Oh and Johannes, I do have the v4l_compat module loaded, so I don't know
why xawtv reads my v4l2 video stream but Gem does not. Any ideas?

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