On Thu, 2007-11-22 at 17:07 +0100, Richard Spindler wrote: > 2007/11/22, Burkhard Plaum <[EMAIL PROTECTED]>: > > > Problem #6: Temporally compressed Video processing, MPEG, GOPs > > > Subproblem 1#: „Give me Frame 10"! No matter whether B, P or I > > > Frame. No consideration of Performance. > > > > This is handled by libquicktime and (AFAIK) by quicktime4linux as well. > > Needless to say, that editing temporally compressed sources is suboptimal > > to begin with...
Temporally compressed video aquisition formats are already a fact of life, both for amateurs (DVD, HDV and AVCHD) and professionals (XDCAM, Betacam SX, others?). I don't expect them to go away any time soon. For quick editing turnaround, optimal quality and viable disk space requirements, it is vital that Cinelerra supports compressed source material well. > btw. the following problem proposition was posted by salsaman on the piksel > ML: > > Am Freitag, den 16.11.2007, 18:57 +0100 schrieb [EMAIL PROTECTED]: > > - on the fly mpeg decoding - needs to be fast, so for example if I ask for > > frame 110, I don't care if the decoder gives me frames 105 - 115 for > > example - host can cache these and pull the frame which is required. > > While accurate positioning is good, for certain use cases, speed is > more important, for example through fast-forward, or quick seeking, > scrolling through footage. Maybe the codec libraries need some NLE extensions to support "sloppy" decoding, at least for the most common aquisition codecs. For example, instead of asking the codec for a particular frame, one asks for a range, and gets the frame that is fastest to retrieve within that range. The codec also needs to cache frames, or use Cinelerra's frame cache to avoid a lot of repeaded decoding. If the codec has to decode frame 2-4 to deliver frame 5, it should be able to reuse those for decoding frame 1 or frame 6 later. (memory or disk footprint permitting) -- Herman Robak _______________________________________________ Cinelerra mailing list [email protected] https://init.linpro.no/mailman/skolelinux.no/listinfo/cinelerra
