Hi, List I'm starting to try to burn video from bt878 to CD. 1) I do the grabbing with the only tool I found that ensures very good sync between audio and video, which uses low CPU, which runs without framedrops at high resolutions at a K6III-450 and which keeps sync also in case of eventual framedrops: "mp1e" 2) Finally I want to have a File with MPEG4 and MP2/3 inside. So I convert the movie with ffmpeg from MPEG1 to MPEG4. 3) The resulting video quality is always worse than the MPEG1- source. Even with high bitrates. I found one systematic problem: Isn't the MPEG4-format meant to allow for better quality at low bitrates? Of course, conversions are lossy. I'm not quite sure, but I think, that the MPEG4-encoder suffers from the MPEG1-artefacts, and it could give much better results at the same bitrate, if it would get a more original-like picture for input. Two questions come to mind: 1) If there is a large harddisk availlable, one could bear a relatively low, but sufficiently artefact/lossless encoding while recording and recompress better afterwards. Which tools are availlable for this? (reliable capture and optimal recompression) 2) Could ffmpeg's encoders benefit from a postprocessing-filter between the decoder and the encoder while doing recoding? One text I read at the internet gave theese thoughts to me: At "http://www.math.berkeley.edu/~benrg/huffyuv.html#MJPEG";, which describes a project for lossless video-grabbing one can read: > Why not use Motion JPEG? > If you capture video in order to edit it and output it back to tape, > then Motion JPEG is probably perfectly adequate. It's also a good > archival format. However, if you're producing MPEG video (or any lossy > format), you should avoid using MJPEG (or any lossy format) in your > intermediate files if you can. The reason is that JPEG was designed > for viewing, not image processing. JPEG achieves its compression > by exploiting known weaknesses in the human perceptual system, but > computers don't see images the way people do: an MJPEG clip which > looks fine to you may not look so good to an MPEG encoder. As > a rule, MPEG encoders are very sensitive to noise, and MJPEG > is basically an avoidable source of noise. Regards, Ralf ----------------------------------------------------------------- | Ralf Oehler | GDI - Gesellschaft fuer Digitale Informationstechnik mbH | | E-Mail: R.Oehler@xxxxxxxxxx | Tel.: +49 6182-9271-23 | Fax.: +49 6182-25035 | Mail: GDI, Bensbruchstraße 11, D-63533 Mainhausen | HTTP: www.GDImbH.com ----------------------------------------------------------------- time is a funny concept
