Playback of AC3 files emits loud bursts of static

jkowtko · Post by **jkowtko** » Mon Mar 10, 2008 3:30 am

Mike,

It looks like the playback of AC3 files is not 100% solid yet --

When running fade cues or simply playing the next cue, when an AC3 is playing, I get occasional very loud, short (~50ms) bursts of static, what appears to be at full sound card volume.

This happened once at the theater last night during our run-thru ... scared the heck out of us!

I was able to reproduce it on my laptop at home, so I know it's not the new Delta cards are the theater.

I was also able to identify that if I pre-load all audio files I do not get the problem, but if I leave the pre-load to my standard 5, I will get the problem. So presumably it is happening during the process of SCS opening the next file in the cue list while playing or fading out an AC3.

I will try to put together a simple test case to send to you separately.

In the meantime I just wanted to caution others who may be using AC3s ... and find out if anyone out there has experienced this issue and has other info to contribute.

Thanks. John

jkowtko · Post by **jkowtko** » Mon Mar 10, 2008 6:36 am

Just a quick update after some more testing --

* appears to be affected by the playback buffer size. If I reduce the buffer size from 5000ms to 200ms it almost eliminates the chance of it happening.

* If I set my file pre-load count high enough to pre-load all cues in the program, it appears to completely avoid the problem.

* I have never heard this with MP3 or WAV files ... only 6 channel AC3.

-- John