Hi Patrick,
As Marius noted, the best CODEC depends on what you are going to do with the video. The MPEG gang of CODECs (from MPEG-2 on through H-264) are very good for standard playback and have a good quality/file-size ratio. All visual CODECs use spatial coding - reduction of perceptual redundancies in the 2D plane of a given frame; but another way these CODECs achieve such good ratios is by using temporal coding to reduce frame to frame redundancies. They take a GOP (Group of Pictures, not an antediluvian near-extinct political party) and make decisions about what information is important. Some frames are fully represented and other frames are coded with reference to the ones around them. This saves a lot of space, but you do not have a full representation of each frame. During normal playback this is not a problem, but if you want to mess with the playback rate it is.
If you want to do any scrubbing, varispeed or playing backwards of the video, you need a CODEC which does not use temporal compression. Photo-JPEG is in fact a very good choice in this case and if compressed at 320 X 240 you get a good balance of file-size, picture quality and processor load. JPEG 2000 should also be a good choice (supported by QuickTime and there are libraries which support it on Linux but not sure if it will play in GEM). I have used DV video with good results and this may be a good option if you need high quality playback.
However, if you have unlimited bandwidth and storage, why not just go for uncompressed D-1 video? (~30M/s) ;)
cheers, Andrew
On Fri, 30 Nov 2007, pd-list-request@iem.at wrote:
hi,
i am on linux running the very last version of gem from cvs. i am trying to find a good codec for gem. here's my basic research:
the best codec for quicktime is jpeg: transcode -i yourvideo -y mov,null -F jpeg,,jpeg_quality=70 -o gem.mov
gem cpu usage is 38% mplayer cpu usage is 27% ffplay cpu usage is 16% lqtplay cpu usage is 1% **
for avi i tried ffmpeg / mjpeg: transcode -i yourvideo -y ffmpeg,null -F mjpeg -o gem.avi
gem cpu usage is 33% mplayer cpu usage is 33% ffplay cpu usage is 22%
the really best codec around is mpeg4: transcode -i yourvideo -y ffmpeg,null -F mpeg4 -o gem.avi
gem cpu usage is: crashed** mplayer cpu usage is 16% ffplay cpu usage is 11%
- lqtplay seems to make a excellent job for decoding is own codec. would
it be possible to make a pix_qt based on the source of this player???
** anybody can test this codec? that would be my second choice... after lqtplay ported to gem...
pat