Date: Mon, 22 Dec 1997 10:16:24 -0800 From: Amancio Hasty <hasty@rah.star-gate.com> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: rhh@ct.picker.com (Randall Hopper), multimedia@FreeBSD.ORG Subject: Re: MPEG audio/video sync & Re: These mtv video pauses are murder Message-ID: <199712221816.KAA01478@rah.star-gate.com> In-Reply-To: Your message of "Mon, 22 Dec 1997 17:32:40 %2B0100." <199712221632.RAA02664@labinfo.iet.unipi.it>
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Thats a resonable assumption provided that the audio clock is sufficiently accurate and typically the SB cards have poor clocks . My guess is that Creative Labs is too busy pumping those cards and in large volumes is kind hard or to expensive to control the quality. Cheers, Amancio > > Luigi Rizzo: > > |I suppose the problem if any will be in the capture phase. We have a > > |way to timestamp (using the cpu clock) incoming video frames (do you > > |use that ?), but e.g. for audio you cannot rely on the sample rate > > > > I do store off a timestamp for each frame of data (video frame + > > accumulated audio to that point). This is used to know how many frames we > > missed, which is how many times the preceeding frame is replicated in the > > mpeg_encode input stream to normalize the video back up to the full FPS rate. > > well my point was that the right (I would even say "the only") approach > to get timing info in a video+audio steam is to use the audio sample > clock. It makes life easier in the reproduction phase since it is much > easier then to keep video in sync. > > Probably my previous posting was confused enough to obscure the above > point. > > Cheers > Luigi > -----------------------------+-------------------------------------- > Luigi Rizzo | Dip. di Ingegneria dell'Informazione > email: luigi@iet.unipi.it | Universita' di Pisa > tel: +39-50-568533 | via Diotisalvi 2, 56126 PISA (Italy) > fax: +39-50-568522 | http://www.iet.unipi.it/~luigi/ > _____________________________|______________________________________
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