Video/Audio Sync?

[gazzer82]

Aha, i hadn't noticed the sync to mtc playmode before you mentioned it. So odd that you can spend so long looking at an interface and never actually clock what's there.

Just need to persuade the venue to purchase the show control sfx license now so that i can actually get MTC from them to reference too.

Though in fairness i have done a lot of testing over the last few days and i haven't yet managed to get the audio/video to slip out of sync. So potentially this may not be required.

Thanks for the help!!

Cheers

Gareth

[Peter]

Just need to persuade the venue to purchase the show control sfx license now so that i can actually get MTC from them to reference too.

We use Qlab instead of sfx but we started with sfx which by the way is for sale (educational version). If your interested please let us know?

QLab and motu are rocksolid on mac.

[SourceChild]

Uh...

Just a suggestion guys but sometimes I will setup an extra Catalyst Machine as an Audio server and sync to it.

[samsc]

Uh...

Just a suggestion guys but sometimes I will setup an extra Catalyst Machine as an Audio server and sync to it.

this is done in a lot of shows-

as professional audio gear does what it says on the tin-

using a mac to playback audio from the sound output - is buyer beware.

[SourceChild]

using a mac to playback audio from the sound output - is buyer beware.

I am curious at your feedback. I've got three different venues that have been playing Audio off their Catalyst machines for years. Easily over 5000 separate instances of playback with audio and I've never heard of problems. (Granted I had a few bugs with V3.3 and older on the old G5 machines.)

Now I have done things in different cases. Sometimes it was literally the 1/8" mini phone jack connected to a stereo DI. Other times an external USB or Firewire Audio device. Most times using SDI audio.

Where have you seen problems occur most.

[samsc]

I am curious at your feedback. I've got three different venues that have been playing Audio off their Catalyst machines for years. Easily over 5000 separate instances of playback with audio and I've never heard of problems. (Granted I had a few bugs with V3.3 and older on the old G5 machines.)

Now I have done things in different cases. Sometimes it was literally the 1/8" mini phone jack connected to a stereo DI. Other times an external USB or Firewire Audio device. Most times using SDI audio.

Where have you seen problems occur most.

it works - its used a lot -

but because using audio playmodes - as i have said before - apple makes the movies prioritise audio - not video- so when you do this the video sometimes does not playback as smoothly as without audio. if the computer is doing too much - apple skips video frames.
this is a bigger problem with systems with only sata discs - and people using lots of layers at the same time.
hunting around for audio as well as video - and they are often on different parts of the discs - within the same movies- makes the rotational latency issues more critical.

[samsc]

I am curious at your feedback. I've got three different venues that have been playing Audio off their Catalyst machines for years. Easily over 5000 separate instances of playback with audio and I've never heard of problems. (Granted I had a few bugs with V3.3 and older on the old G5 machines.)

Now I have done things in different cases. Sometimes it was literally the 1/8" mini phone jack connected to a stereo DI. Other times an external USB or Firewire Audio device. Most times using SDI audio.

Where have you seen problems occur most.

a more general point-
multitasking general purpose computer systems do not prioritise the allocation of any specific system resources to a single task.

a standalone audio playback unit - because it will be designed with only one function - and system resources prioritised to that single function - will likely be more stable. though not always.

---

In the design of general computer systems - it does not matter if a program crashes - or the OS goes and does something else for a few seconds-
In audio visual applications running on general purpose computers - ths behaviour is not appropriate - and there is no means of controlling these things in the operating system.

We have been lucky that it mostly works - almost all the time. and testing on shows over many years has shown adequate performance under long and continuous use. but this is still not exactly how these things are designed.

[SourceChild]

Actually Richard,

You're exactly right. I wasn't sure though if you had additional considerations I haven't considered.

I guess it's a good thing to point out that I run scripts after each big event that set the state of the computer back to the "out of the box optimized' state. I tend to take for granted that the majority of people don't Re-Image often.

On a thought though... I've tried in the past to play audio files in PLAudio mode on Catalyst. Is there a way to integrate an audio only play mode so Catalyst can play audio as well as video files? ...and is there a way to input/output the timecode of it?

[samsc]

Though in fairness i have done a lot of testing over the last few days and i haven't yet managed to get the audio/video to slip out of sync. So potentially this may not be required.
Gareth

thats because - it doesnt 'slip' if the audio and video are in the same movie.
quicktime keeps them together-

--

if the audio and video are on separate layers - then thats different...and depends completely on whether your hardware can playback those layers without dropping frames-
typically with sata discs arent good enough- to keep long term stability-
if you get a machine with an SSD then you reduce the chance of dropping frames by many times-
If you are doing audio and video - i would very very strongly recommend the use of SSD's - to minimise any dropped frames caused by rotational latencies.

---

in the most recent versions of catalyst- there is a smpte reader for the audio input - so midi timecode isnt required.

[samsc]

Aha, i hadn't noticed the sync to mtc playmode before you mentioned it. So odd that you can spend so long looking at an interface and never actually clock what's there.

Just need to persuade the venue to purchase the show control sfx license now so that i can actually get MTC from them to reference too.
Gareth

you dont need MTC - you can input timecode directly into the audio port and sync a layer to the incoming timecode directly-
You can also set time offsets for the inframe for catalyst layers.

just been used on sinatra tour.