Subject: Re: [linux-audio-dev] MTC, SMPTE, etc.
From: Jörn Nettingsmeier (nettings_AT_folkwang.uni-essen.de)
Date: Mon Jul 24 2000 - 00:43:55 EEST
Paul Barton-Davis wrote:
>
> >I'm doubly confused... I was under the impression that SMPTE resolved to
> >"bits" which are 1/80th of a frame (at whatever frame rate we are using)...
>
> Ah. OK. I've used SMPTE-via-MTC so far, and I've never managed to find
> specs on the analog version of the signal. I assumed that SMPTE was
> limited to the same resolution as was represented in the MTC stream.
>
> Apologies if this is wrong.
>
> >i.e. approx. 0.5 ms
>
> but still pretty weak as a timebase for positioning an audio stream, eh ?
given the normal usage of smpte, which is synchronizing a/v, and the
time it was invented (mostly analog gear), it's ok imho.
hope i don't get beaten for this, but what is the practical use of
having phase-accurate or even sample-accurate locking between
devices anyway ? (except for scenarios that can be solved by placing
two timing-critical tracks like xy-stereo on one machine.)
throwing 44k timestamps per second around seems like masturbation
(quoting linus here): it might feel good, but you won't actually get
much done :D
plus you can record smpte on analog gear. i dare not compute the
bandwidth needed for 44k timestamps/sec, but i think you'd need 192
khz...
just my 10e7 nanodollars,
jörn
-- Jörn Nettingsmeier Kurfürstenstr. 49 45138 Essen, Germany http://www.folkwang.uni-essen.de/~nettings/
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