On Wed, 2006-11-29 at 09:30 -0500, Dan Maas wrote: > > What do you have in mind when you say lossless re-encoding ? > > If a frame has already been passed through a DV codec, then it is > (theoretically) possible to re-encode it with no quality loss, by > using the exact same bitstream. This is desirable for video editing > systems where you might end up re-encoding a frame several times. You > can even do sub-frame lossless re-encoding. For example, if you > super-impose a title on top of the video, any macroblocks not affected > by the title could be re-compressed losslessly. That's what I thought. So basically, if I understand you correctly the only application of such a lossless re-encoding would be to do a sort of "injection" of additional video material into an existing DV frame. Titles, of course, spring to mind right away, but they also bring the fundamental difficulty of doing so with DV to the surface -- titles (as I would expect any kind of such "injection") are quite localized and "linear", DVs macroblocks on the other hand were specifically designed to have DCT blocks shuffled all over the frame. Which means that in order to inject something, lets say, close to the bottom of the frame you will also have to requantize quite a few DCT blocks without any relation to the bottom of the frame. My fear is that it might actually void all of your efforts, simply because such "collateral" changes will sweep a pretty wide area pretty quickly. What do you think ?
> > > - ffmpeg's DV-in-MOV encoding is broken. It does not insert the DV > > > audio and header data into the embedded DV stream, as required by > > > Quicktime. > > > > Most of the issues regarding video have been fixed. If there's > > anything that remains -- please let me know. > > The problem is that when ffmpeg creates a MOV file with the DV codec, > it uses only the video encoder, not the DV muxer, I've fixed that. Everything that doesn't require a knowledge of frame counting or audio is now being inserted by a codec, not by a muxer. The only pieces left are those having to do with audio. Or may be you're saying that even this is not good enough for your application ? Thanks, Roman. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
