Fixing stuttering, skipping or stalling audio

[Mike Daniell]

If you are encountering stuttering or skipping audio, this is probably due to "buffer underrun", which means the program is not filling the playback buffer fast enough from disk. You should find this will be fixed if you choose not to use the SCS internal mixer. The default playback buffer size when using the internal mixer is 200ms (it has to be short), but when not using the internal mixer the default playback buffer size is 5000ms.

Set the required options as follows:

• Click on General Options / Permanent Options
• Click on the Audio Driver tab
• Select Do NOT use SCS internal mixer
• Make sure the buffering and update options on this tab are all set to SCS default...

Then click OK to save the changes, and close and restart SCS.

[Mike Daniell]

The above posting is applicable if you are using 'DirectSound (using BASS)' as your Audio Driver in SCS. However, since SCS 11.1.3 we recommend you use ASIO instead of DirectSound, provided you have an ASIO driver for your sound interface. SoundMan-Server users always use ASIO, but if you do not have SoundMan-Server then select 'ASIO (using BASS)' as you audio driver.

The reason for the ASIO recommendation since SCS 11.1.3 is that a new version of the BASS audio library has been included, which addresses the buffer underrun problem that frequently occurred in earlier versions.

However, SCS user John Hutchinson recently reported that cues were intermittently stalling, even when using ASIO. After a fairly lengthy investigation, during which we established that SCS seemed to be correctly playing the cues that were stalling, John sent me the following email (Therese Raquin is the name of the show):

Just thought I'd let you know what was causing our problem.

Our Sound PC has two hard drives, we use drive C as the system disk & drive D as the data disk. All the audio files for Therese Raquin were on the D drive.

After further investigation it appears that although “Do not power down hard discs” is ticked in the “Power Options” pane in Advanced Settings in Windows 7, this only applies to the system disc. The data disc will always power down if not accessed within 10 – 12 mins.

All the audio files for Therese Raquin were loaded onto the system drive (drive C). This cured the problem.

So from now on we will use drive C to store the audio files for the current show.

And subsequently, John emailed me this:

I found out that Windows 7 only keeps the system drive running, through searching various forums on the internet. Apparently it's the bios in the hard disc drive that causes the drive to power down if not used for 10 -12 mins & cannot be overridden. The system disc keeps running because the system processor keeps accessing it.

So please keep all your files on the C: drive, or on a drive that doesn't power down, such as on an SD card.

[lebem]

I don't know if this is universally the case with Windows 7 and non-system drives.

I've learned that Western Digital drives absolutely ignore the OS settings and spin down as a result of the drives bios much as you describe in your guidance on this issue. However, at least as of the time when I researched this after having this problem years ago, not all manufacturers program their drives with this behavior.

So, while some research might be necessary before purchasing secondary drives for audio playback, I think it is possible to buy drives which will adhere to the OS settings and not spin down.

[Eric Snodgrass]

Another, somewhat related issue, is that Win 7 has, as its power options, a default that will shut down USB port power if not accessed for a certain amount of time. I learned this when using my laptop on location to record some dialogue for a shoot. When not accessed for about 10 minutes or longer, the recording program would not recognize that there was an external USB sound card attached, meaning I had to go into the program's audio hardware setup and choose the sound card as the default every time after this happened.
To change this default for Win 7, go into Control Panel>Power Options>Change Plan Settings>Change advanced power settings. A window will pop up. Scroll down to USB Settings. Click the +, then click the + next to USB selective suspend setting. Choose Disabled as the setting and click on Okay at the bottom of the window and your USB ports will stay powered.