Subject: [linux-audio-dev] MIDI timecode, mea culpa
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: Fri May 05 2000 - 10:15:38 EEST
Once again, I hang my head in shame.
It turns out that the MTC receiver in my case (a mackie digital 8 bus)
was quite happy to recieve MTC with enormous jitter. What it didn't
like was being sent multiple sets of 4 qtr frame messages that
indicated the same value. I put in some code to do the "frame
catchup", added a quick printf to see what it was doing.
This helped me realize that because I was running with audio 5msec
latency, there was less than 1 SMPTE frame per audio interface
interrupt. My old code had sent a qtr frame message unconditionally,
resulting in duplicate MTC messages.
As a test of the new code, I also ran with about 100msec latency, and
the mackie was happy as well. This is despite a huge "error" in the
delivery rate of MTC. So it was clearly all my fault.
For now, problem solved, shame absorbed, i move onto the next step in
the long, arduous path (x-fade on punch out).
:)
--p
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