CurrentPositionInfo.timeInSamples and tempo changes in ableton live


#1

It seems that the timeInSamples given by Live is wrong when the tempo changes (tested with vst2).
When getting timeInSamples in processBlock(), I expect it to increase by numSamples, whether the tempo changes or not.
But the tempo changes seem to make some timeInSamples jumps.

Am I missing something, or is it most likely an ableton bug?

diff.txt (1,5 Ko)

frameSize 512
timeInSamplesDiff 512
frameSize 512
timeInSamplesDiff -1261
frameSize 512
timeInSamplesDiff 512
[…]
frameSize 512
timeInSamplesDiff -1305
frameSize 512
timeInSamplesDiff 512


#2

As someone who just implemented variable tempo in their DAW (which is a nightmare) this is really fascinating to see.

I feel confident saying this is probably a Live bug, perhaps with the time->tempo mapping algorithm they’re using giving back the wrong time (maybe they’re going time->tempo->time->samples?).


#3

Wow, that’s interesting. This definitely looks like an Ableton bug. JUCE’s timeInSamples comes pretty much straight from VST2’s audioMasterGetTime opcode and JUCE does not do anything special with this number - it just passes it on to you.


#4

I’ve reported this bug to Ableton. Let’s wait and see what they say…


#5

Ableton has a new bug reporting system. Can you let me know exactly which Live version (i.e. x.x.x) you encountered this bug. Which OS were you using? 32-bit or 64-bit?


#6

Is that public? I like when companies have a simple support email or a public way to report bugs…

anyway:
live lite 9.6.1 - macOS 10.3.3 64 bit


#7

@lalala Yes it is. It might be better that you file the bug. Let me know the ticket number so that I can make sure that it is escalated.

https://ableton.centercode.com/key/developer_tickets