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Envelope Errors With Multi-Channel Tracks Issue Tools
issueid=3025 10-21-2010 09:56 PM
Human being with feelings
Envelope Errors With Multi-Channel Tracks
Envelope Errors With Multi-Channel Tracks

Reaper 3.72, 32-bit Win XP Professional 2002 SP3

Automation envelopes do not behave correctly if the track has more than 2 audio channels.

Screen capture video: https://stash.reaper.fm/6955/Envelope...ng%20Error.gif

(Sorry for the low-quality frame rate -- I wanted to keep the file small.)

The project has 6 tracks -- all identical except for the number of audio channels (2, 4, 8, 16, 32, and 64 from top to bottom). All tracks have an identical envelope to automate the same ReaDelay parameter.

Notice how the envelope fader for the 64-channel track jumps to the final value at about beat 2.1.16, well before the envelope actually reaches the end (at 5.1.00). The 32-channel track does the same thing a little while later (at about beat 3.3.06), followed by the 16-channel track (4.2.06), the 8-channel track (4.3.54), and the 4-channel track (4.4.30). The fader for the 2-channel track reaches the maximum value at 4.4.63, which is pretty close to the correct time with respect to the drawn envelope (I assume there might be some scaling/rounding causing the fader to reach +6.0 a little before the value of 5.1.00 defined by the envelope).

A rough estimate shows that the timing error is linearly proportional to the product of the number of audio channels and the ASIO buffer size. I need to verify my ASIO buffer size when I get home. I think it is 4096. If it is, that is roughly 95 ms. The 32-channel track jumps to the max value about 3 seconds early (32 * 95 ms = 3.040 seconds -- a pretty good match); the 64-channel track jumps to the max value about 6 seconds early (64 * 95 ms = 6.080 seconds -- another match); etc.

This is reproducible with any FX, not just ReaDelay.

Example project: https://stash.reaper.fm/6956/Envelope...ng%20Error.RPP

The tempo affects the absolute beat at which the faders jump to the maximum value (try playing the project at 60 BPM instead of 120 BPM to see the difference), but the trend is still the same -- adding more channels increases the timing error in the envelope playback.

See additional videos and discussion here: http://forum.cockos.com/showthread.php?t=67394

----

Based on the discussion thread, it seems that the size of the ASIO buffer has something to do with this. Larger buffers make the errors more obvious.

I also can add some additional information: It seems that the timing error is measured from the end on the envelope, not the start. If I make the envelope ramp over 8 measures instead of 4, the jumps all shift 4 measures later, which maintains the same "delta time" between the jump points and the end of the envelope. When I cut the tempo in half, the jump points all shift to the right, and again maintain the same "delta time" between the jump points and the end of the envelope.

However, this is not just a playback issue. If I stop the transport and click on the timeline to move the edit cursor, the fader(s) will jump to the incorrect value(s) just like they do during playback.
Issue Details
Issue Type Closed Issue
Project Deprecated REAPER issue tracker
Category Audio recording and playback
Status Fixed
Priority 3
Affected Version 3.69
Closed Version 4.53
Yes votes 5
No votes 0
Assigned Users (none)
Tags (none)

10-28-2010 07:15 AM
Human being with feelings
 
Has anyone had time to look into this one?

Several people confirmed it in the discussion posts.

I was hoping for a developer or a moderator to comment on it here, just to reassure me that I provided enough information for you to verify the issue.

Thanks.
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05-26-2016 06:59 AM
Human being with feelings
 
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