live out of sync when using 3rd party plugins

[kayhel]

Hi Musicians,

I have a big problem when using live 8.2:

I'm using groups and also need to group the groups again - therefore i send them to another audio track, where i set "monitor" to "in" and "A. from" to "no input". works fine. audio also is in sync when playing. I have some 3rd party fx plugins on the track, the group and the routed group, which obviously add latency to the chain track > group > routed group.

Now, the VU Meters on the tracks are out of sync from each other and out of sync from the audio sent through the soundcard. I.e. when the Kick is hit, the BD track meter shows the Kick as being played according to the position indicator, the group some 300ms later, the routed group another 300ms later and finally the master meter as being outputted through the audio interface. I get crazy when finding which tracks are playing what note / beat... The whole setup "looks" like being fully out of sync (but sounds in sync).
Also the song position indicator is completely wrong, it seems to follow the track input, not the audio output.
When I am recording audio now, it is fully out of sync - way behind.

This is very annoying.

Delay compensation is switched on. Tried on different computers, different soundcards with different plugins and with various buffer sizes - all the same:-(
I would expect that the visual experience would be in sync with the audio output regardless of the delays the plugins are causing.
Also that it would compensate the delay when recording audio during song playback.

It seems that audio compensation does not include the visual meters and does not work for recording audio tracks.

Any idea?

thx
cheers
Kay

[Ableton_David]

Hi Kay, how big is/are the set(s) in question? What plug-ins are you using? What sound card are you using?

[kayhel]

Hi David,
you can easily reproduce it doing the following:
1. Create a track with a part with a 4 on the floor kick
2. Duplicate the track
3. put an ozone4 plugin on the second track, use something like "basic house mastering" which creates > 100ms latency
4. put the second track in a group
then play:
with delay compensation off, you here two kick attacks, the grouped one delayed ~ 100ms (as expected)
with delay compensation an, audio is in sync, but the meters are still out of sync (track 1 is 100ms ahead before the group that contains track2) and the position locator is 100ms ahead of audio.

It is independent from soundcard and buffers, also independent from plugin (applies for every plugin that has an input / output lag, which is almost everything)

I will attach a screenshot later,

The more plugins you add in this scenario and the more chains you create (i.e. use audio tracks to create subgroups for the groups) the more the meters and the position locator gets out of sync.
From ~ 300 ms on, i am no more able to follow the voice content in audio tracks, so i am setting wrong warp markers etc. And wrong automation as well.

Just found yesterday that this seems to be a known bug inside live - from the beginning on?

many thanks
cheers
Kay

[kayhel]

additional info:

- the recording stuff is solved - it's working correctly when setting monitor to off. I use my mixers monitor instead.

!! But the meters, the position marker and the automation is a big problem !!
I just thought last night on what should be the reason for this issue not being solved while audio is fully in sync and found the following:

---- For the live-developers audience: ----

1.) Syncing the meters would be more difficult than i expected first, because you need additional buffers per meter (adds cpu and memory). What i would like to see at least is that the track meters (of every track/instrument that can be expanded!) are in global sync. That means that you need an additional buffer per track meter and to delay the metering output with formula "trackMeterDelay = globalPDCtime - PDCcalculatedTrackDelayTime + calculatedAudioHardwareDelayTime". Buffering Meter Level every 10ms (100Hz) should be more than sufficient, so you need not more than 200 bytes buffer size per track meter in a complex scenario (1s global delay, 16bit resolution). For syncing all the meters in the plugin chain this would be more complicated - i understand! Btw: it seems that the track meters currently do not reflect the audio hardware delay. They should...

2.) Syncing the position locator is a very easy task. Just take the "globalPDCtime + calculatedAudioHardwareDelayTime" instead of the currently used time (Actually i couldn't find out which delay time live uses for the position currently: It seems to be more than the calculatedAudioHardwareDelayTime but less than the globalPDCtime, maybe something like the maxChannelDelayTime of every _single_ channel - but definitely not the delay of the whole multi channel chain)

3.) Syncing automation should also be not that difficult - but differently to 1.) and 2.) I assume here, that all automation happens after the sound source but before the first FX plugin. At least it would make sense there in the arrangement view. Then you just need to delay it to the exact amount of the sound source track delay (PDCcalculatedTrackDelayTime) - i wonder if this would be complicated?

thx
cheers
Kay

[kayhel]

And a last thought to 3.):
Automation for chained plugins and mixer channels obviously cannot be timebased on the instrument which is creating the sound, so my assumption here was not correct. But it is definitely not impossible:

You seem to know the delay that each single instrument / fx / plugin is causing, otherwise the audio delay compensation wouldnt work, right? So you could easily calculate the current delay for each instanced plugin (by summarizing the delays up to the soundsource) and delay the automation data for that specific plugin by exactly this value (thisPluginTotalDelayTime = previousPluginTotalDelayTime + thisPluginDelayTime). That would compensate the negative automation "delay".
Also this value would be helpful for syncing the visual indicators for each plugin (in the live chain only, not inside the plugin), because you would need to delay it up to the totalPDCtime. thisPluginVisualDelayTime = totalPDCtime - thisPluginTotalDelayTime + audioHardwareDelayTime. Use same method as for the track meters, see in my previous post, but with this different buffersize.

Then everything is in sync, audio, automation and visual indication, right?

cheers
Kay

[Ableton_David]

Hi Kay, please get in touch with Ableton Technical Support about this. Please copy over the information that you have shared here. You can get in touch here: http://www.ableton.com/support. Thank you.