[5206] Audio glitches on Tempo change in Session View

[gavinwhiteley]

In Session View, changing tempo causes a hiccup in the audio:
a brief silence about 0.2 sec after the start of audio, a pop in the audio outputs, then audio streaming continues.

Sounds almost like I am changing the sample rate on my sound card or master clock.

All audio clips have Warp off and Clip Fade off. Using less tracks make the glitch less severe, but it is still there even with only 2 tracks.

Here's what does cause this error in Live 8, but not in Live 7.0.14, with the same project on the same computer:
- Triggering back & forth between scenes named "240 BPM" and "200 BPM"
- Adjusting tempo in the Control Bar while a scene is playing in Session View, or Arrangement View

Here's what does not create the error in Live 8:
- Triggering back & forth between 2 scenes named "240 BPM"
- Triggering back & forth between scenes named anything besides "BPM"
- Jumping to markers in Arrangement View that have different Tempos on the Master Track
- Never ever changing Tempo

I've had this with b14, b13 and b12... but again, not with 7.0.14.

System (2 identical ones):
WinXP SP2
Intel Quad Core 2.4GHz, 4GB RAM
RME HDSP MADI sound card
Apogee master clock & D/A converters
Mtron MOBI SSD audio drives

[gavinwhiteley]

A simpler version:

Put an audio clip in Session View, Clip Warp OFF.
OR...
Put a MIDI clip playing Sampler on a track.

Play your clip. Scroll the Tempo up and down with your mouse in the Control Bar.

In Live 8, the audio skips and stutters as if I was scrubbing. CPU jumps from 7% to 16% and Disk Overload lights up.

In Live 7, the audio does not change. CPU jumps from 7% to 16% but Disk Overload does not light.

It appears to me that in 8, the relationship has changed between tempo change and the audio streaming buffer.

Why is this? Did I miss this in some other post?

Thank you all...

[forge]

I wonder if it's at all related to this: http://forum.ableton.com/viewtopic.php?f=25&t=109146

[gavinwhiteley]

Possibly part of the same animal - though I am experiencing it consistently without any warping, and at any tempo.

The difference in tempo change behavior from 7 to 8b14 is quite fascinating...

[Amaury]

Hi,

I can't get to reproduce this. First, can you try if it still behaves the same in beta 17?

Regards,
Amaury

[gavinwhiteley]

Hi Amaury,

I get the same behavior in beta 17, 18, and 19 - on PC (see signature) and my MacBook Pro (10.5.6)

Perhaps the best way is to demonstrate this - please download the one Live pack posted at this drop:
http://drop.io/majorscaleaudio

This set was made in Live 7. Computer keyboard is mapped to scenes. Audio tracks all have warp off.
Scenes:

Open this in Live 7, and start any scene (1-8), all at 106 BPM. Now jump to scene q/w/e/r/t/y - scenes with no stop clips.

In Live 7, nothing happens.... the audio tracks keep playing normally, uninterrupted, no change.

In Live 8 - all the betas I've seen - jumping to scene "q" changes nothing, because the tempo is the same.
But scenes w/e/r/t/y shift the play position of the clips still playing, proportionate to the new tempo.

This is clearly visible in the Track Status Display, and is 100% consistent across all tracks in a (unwarped) multitrack session.

For the record, I tried the same thing with frozen and consolidated tracks - same result.

It's not clear to me that this behavior is intentional - for our shows, this is certainly not desirable. We rely on being able to play audio tracks from one scene tempo, then jumping to a new scene and tempo, while leaving some clips playing (no stop clips in the new scene). In Live 8, the already triggered clips are shifting the play cursor position, which sounds like an "audio glitch" - my first diagnosis.

Please let me know if you have trouble reproducing or observing this behavior. Thank you very much for your assistance.

[Amaury]

Hi,

Thanks, I could reproduce the problem thanks to your file and clear instructions. The bug is filed now.

Regards,
Amaury

[gavinwhiteley]

Fantastic! This is now working - problem fixed!

That was the last bug that was affecting me - I am now looking forward to purchasing Live 8 when it emerges from beta.

Thank you so much for all your work!