playing files with different sample rates at the same time

[Jonas Nordgren]

Hi. Is Qlab3 happy with playing files of different sample rate at the same time? I have video files with audio running at 48 kHz and audio files running at 44,1 kHz. I have learned that Qlab converts everything to match the output device, which is, a Mackie Onyx 1220i - an analog mixer with a built in firewire interface. The operators manual for the mixer tells me that it accepts both sample rates but there is no way of telling it to stay put in one state. Could this be a problem? I do experience some issues with audio lagging.

Best regards
Jonas

[Christopher Ashworth]

Hi Jonas,

On Oct 7, 2013, at 4:28 PM, Jonas Nordgren <jonas.k....@gmail.com> wrote:

> Hi. Is Qlab3 happy with playing files of different sample rate at the same time?

Yes. The files will be converted to the sample rate of the audio device.

> I have video files with audio running at 48 kHz and audio files running at 44,1 kHz. I have learned that Qlab converts everything to match the output device, which is, a Mackie Onyx 1220i - an analog mixer with a built in firewire interface. The operators manual for the mixer tells me that it accepts both sample rates but there is no way of telling it to stay put in one state. Could this be a problem?

The device will only run at a single sample rate at a time. QLab will match whatever the driver is running at.

> I do experience some issues with audio lagging.

This would be a separate issue. There are a number of reasons a cue might lag:

• It may help to auto-load / pre-load the cue.
• Check that the hard disk is not set to go to sleep.
• Check that other software is not making heavy disk access at the same time as QLab.
• etc.

best,
Chris

[Jonas Nordgren]

Ok, thank you for fast response. Yes, I know there could be a lot of different explanations for lagging audio and I will get back to you with a more detailed report if we do not find a solution ourselves. I just thought that I had the trace of something with the sampling frequencies. I support one of our technicians and do not have the full picture of his issue yet. The examples you mention seems however not to be the problem this time but, as I said, I will get back to you if we do not solve it.

Best regards

Jonas

[Sam Kusnetz]

Hello Jonas

Sam here, another member of the QLab team. I want to chime in to point
out that while QLab is perfectly happy playing audio at different sample
rates, there is the possibility that if your computer is near the limits
of its processing power, the work of converting the audio to the
hardware sample rate in realtime might be having an effect on
performance. Manually converting all your audio to the hardware sample
rate ahead of time might help a very small bit.

Cheerio
sam

--
Sam Kusnetz
QLab Support Operative
s...@figure53.com