Topic: latency, buffering, protools 9 – confused!

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Replied August 19, 2011 at 08:29 #1951032

John
Moderator

The latency is the result of the Buffer Size, which the computer needs to be able to interpret the incoming signal and decide how to deal with it, so to speak.
Now, 64 samples Buffer Size @ 88,2kHz would (at least in theory) mean 0,72 ms latency (in live practice it would be at least times 2). This you cannot hear. Most ordinary musicians do not notice a latency of 10-12 ms. Drummers are generally more sensitive, of course.
Pro Tools 9 (and most other DAWs) takes any buffer sizes into consideration when recording and aligns audio and MIDI correctly. When playing back and latency inducing plugins are present, the correct amount of samples are compensating each track’s delay, making use of the Automatic Delay Compensation.

IOW, don’t worry and don’t nudge.

Best Regards,
John

John Rammelt - Toontrack
Technical Advisor

Replied August 19, 2011 at 15:11 #1951042

btlguy
Participant

Thanks so much for the info. I have a related question, that when answered, should put to rest my latency concerns, and my incomplete understanding of the issues, although much better now. “In theory”… at a sample rate of 44.1 with hardware buffer size of 64, is the latency identical to a sample rate of 88.2 with buffer size 128 samples? Makes sense in my mind, but trying to confirm the math. Also…what is the formula “in theory” for calculating ms of latency based on buffer size? How did you come up with the numbers in your reply. Thanks, and that should do it for me!

Replied August 19, 2011 at 15:54 #1951045

John
Moderator

Buffer Size / Sample Rate ≈ Latency (times 2 if it’s a I/O round trip and, depending on hardware involved, external delay)
128 / 44,1 ≈ 2,9 ms
64 / 44,1 ≈ 1,45 ms
128 / 88,2 ≈ 1,45 ms

At least this is how I calculate, someone better informed may correct me, should I be wrong.

John Rammelt - Toontrack
Technical Advisor
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latency, buffering, protools 9 – confused!

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