Re: SMPTE parsing algorithm?
Re: SMPTE parsing algorithm?
- Subject: Re: SMPTE parsing algorithm?
- From: Herbie Robinson <email@hidden>
- Date: Mon, 14 Jan 2008 11:13:14 -0500
Correct on both counts; however, I believe the existing algorithms
are correcting for non-locked sample frequency clocks which are high
frequency and low jitter. The output from parsing LTC is low
frequency and high jitter. It is possible in a post processing
environment: You could low pass the frame clocks with a massive FIR
low pass filter to get rid of jitter and compensate for the delay by
shifting samples. You still have the problem of picking the corner
frequency that responds to speed variations fast enough, but doesn't
let jitter through. Given that the audio quality is compromised by
gunky heads, too, it would seem to make more sense to redo the
transfer.
2008/1/14, Herbie Robinson <email@hidden>:
They can be filtered to average them out, but that probably won't be
any good for driving a time stretching algorithm to compensate for
local variations (I'm guessing that's what you are thinking about
doing?).
I think you're talking about "varispeed" here... Time stretching would
preserve pitch, which would result in the corrected track having the
right timing but variations in pitch.
Btw. there was some free sample code somewhere which demonstrated the
capabilities of the CAClock class for exactly this purpose. I'm pretty
sure Bill and the others from the CA team know where it can be
found...
--th
At 1:30 AM -0500 1/14/08, Jaime Magiera wrote:
If the tape was gunky, the LTC is going to have problems as well.
Yikes, that's 2400 possibilities for error per second. Good luck.
If tape was that bad, the audio would probably be audibly
compromised. LTC will actually survive encoding as 128Kb MP3, but
not much more than that (surprised me, too).
Does sound like this LTC track might make a nice test case.
--
-*****************************************
** http://www.curbside-recording.com/ **
******************************************
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden