We recently ran into a problem where an audio track being played to three pairs of speakers was time-delayed to at least one pair. The cue sequence started with a track of a clock chime playing from speaker pairs 1/2 and 3/4. At a variable time into this cue, depending on the action onstage, the next cue was triggered to play via speakers 1/2, 3/4 and 5/6. At this point both cues were running and we could hear the second audio track (peoples' voices) repeating with a delay of about 2-3 seconds. We found we could fix the problem by either disabling the internal mixer, or by adding speakers 5/6 to the clock cue and setting their output to zero. We also tried increasing the buffer sizes (between 1000 to 5000ms) while keeping the mixer enabled but this didn't help. I'm curious if anyone has experienced a similar problem or can explain what was happening.
We are using SCS10.6.2 on a Lenovo PC with Windows XP driving an M-Audio 410. The physical devices were set to the 410's 1/2, 3/4, 5/6 and 7/8 outputs each as a left-right pair.
I'd also be interested if anyone can recommend a source where I could learn more about PC audio. I have no clue about ASIO, BASS, CODECs, etc.
Austin
Time delay on outputs to multiple speakers
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Mike Daniell
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Re: Time delay on outputs to multiple speakers
Disabling the internal mixer is the best solution.
The reason, in this case, for not using the SCS internal mixer is that by not using it there is much tighter syncing of linked audio files. This also applies to audio files that are played to multiple SCS sound devices. What I refer to as the 'SCS internal mixer' is, in fact, a mixer add-on supplied with the BASS audio library - which is the audio library used by SCS. If the BASS mixer is not used then audio files to be 'linked' are linked within the audio library itself, and this provides tight syncing. Unfortunately, BASS does not support this internal linking if the BASS mixer is used, so if you are using the 'SCS internal mixer' (= BASS mixer) then SCS uses a short loop to start all 'linked' files as close together as the loop allows. By default, the SCS internal mixer setting is ON, so to not use the internal mixer it does have to be specifically turned off.
The reason, in this case, for not using the SCS internal mixer is that by not using it there is much tighter syncing of linked audio files. This also applies to audio files that are played to multiple SCS sound devices. What I refer to as the 'SCS internal mixer' is, in fact, a mixer add-on supplied with the BASS audio library - which is the audio library used by SCS. If the BASS mixer is not used then audio files to be 'linked' are linked within the audio library itself, and this provides tight syncing. Unfortunately, BASS does not support this internal linking if the BASS mixer is used, so if you are using the 'SCS internal mixer' (= BASS mixer) then SCS uses a short loop to start all 'linked' files as close together as the loop allows. By default, the SCS internal mixer setting is ON, so to not use the internal mixer it does have to be specifically turned off.
