Subject:Sample Rate Changes While recording

Posted by: donlien1

Date:9/5/2010 8:22:33 PM

Hi,

I have been using Sound Forge Audio Studio v7 for some time to record worship services at my church. Recently we have been having trouble with the sample rate used while recording. We normally record using 22,050 Hz, 16 bit Bit-depth and stereo. The file created is immediately saved after the service as an .MP3 file, which I have noticed in the forums here may cause some issues.

The issue that the sample rate will some how double to 44,100Hz in the middle of the file. While this is entertaining for the kids, the Pastor is not amused. The rate change happens at random at least i have not found trigger. The “Properties” of the file shows the sample rate to be 22,050hz but the sound quality of the affected portion of the file sounds like the Chipmunks. Resampling that portion of the file back to 22,050Hz will correct the problem, which just creates a lot of unneeded work.

How can we correct the problem and insure that a constant sample rate is used for the whole recording?

We have upgraded to Sound Forge Audio Studio v10. We are also using the same PC to print the CD labels that will created later, while recording the service. The switch to Sound Forge Audio Studio v10 has not resolved the problem. Would intially saving the file file as a .WAV file resolve the problem?

Any insights would be greatly appriecated.

Subject:RE: Sample Rate Changes While recording

Reply by: ChristoC

Date:9/5/2010 10:18:32 PM

How bizarre!

Only thing I can think of is, you say:
> We are also using the same PC to print the CD labels that will created later, while recording the service.
.... How is that done / what program? .... Does the use of that labeller somehow co-incide with the sped-up parts of the service?

Subject:RE: Sample Rate Changes While recording

Reply by: rraud

Date:9/6/2010 9:41:23 AM

It's defiantly not a good idea to have other applications running. In fact, I recommend exiting ALL applications: screen savers, anti virus, ect, ect, ect,
"Ctrl+Alt+Delete> Start Task Manager> Applications"
If the above doesn't fix it, try another soundcard.

Subject:RE: Sample Rate Changes While recording

Reply by: musicvid10

Date:9/6/2010 10:12:12 AM

Often it means another audio application (a player or "agent") is running in the background and hijacking Sound Forge.

Follow rraud's advice.

Also, make sure Sound Forge is recording and playing back using the actual audio device, not "Microsoft Mapper" or "Microsoft Default Device."

Subject:RE: Sample Rate Changes While recording

Reply by: Steven Myers

Date:9/6/2010 10:33:08 AM

If the audio is going to end up on a Red Book CD, it makes no sense to save it as .MP3. It gets recorded as uncompressed audio (.wav). If you save it as .mp3, it still gets converted back to .wav for burning.
The .mp3 conversion may or may not have anything to do with your problem. But at best, it's an unnecessarily destructive step.

Subject:RE: Sample Rate Changes While recording

Reply by: donlien1

Date:9/6/2010 6:25:57 PM

First off, thanks for the helpful ideas.

We will begin using the .WAV file format for these files. The program we use to print the CD's is the Epson's Print CD. We can print the CD labels before or after the actual recording is being done. I know that Norton Antivirus is running as well, we can disable that too. I'll also kill anything else to get the system as quiet as possible.

I will also check to see what Sound Forge is using as audio device. I am not sure at this point. "Microsoft Mapper" or "Microsoft Default Device" don't look or sound familiar though.

Give me couple of weeks, and I'll post what we learn and how we resolved the problem (assuming we find the root cause).

Subject:RE: Sample Rate Changes While recording

Reply by: rraud

Date:9/8/2010 7:41:09 AM

"I know that Norton Antivirus is running as well"
Norton's security apps are well know to cause problems with many A/V applications.
If you have a integrated soundcard: In SF choose "Classic Windows Driver" (Options> Preferences> Audio tab> Record")
Why record @ 22.2kHz.? Your CD burner will up will just up sample it to 44.1kHz, which takes more time.
Disk space? For spoken word programs for instance, use the WAVE mono mode format if stereo is not necessary. Half the size of a WAVE stereo file.

Subject:RE: Sample Rate Changes While recording

Reply by: roblesinge

Date:9/8/2010 8:11:26 AM

Second what rraud says. If the final destination is CD, you need to record at 44.1k 16b. If it is mostly spoken voice, with no stereo imaging necessary, record to mono.

Even if you're also doing an MP3 for web distro, you would do better to record at 44.1 and then downsample to 22.050.

Rob
:cool:

Subject:RE: Sample Rate Changes While recording

Reply by: Steven Myers

Date:9/8/2010 9:21:48 AM

If the final destination is CD, you need to record at 44.1k 16b. If it is mostly spoken voice, with no stereo imaging necessary, record to mono.

If it's going to be a Red Book CD, the audio is going to be two channels, whether you want them or not.

Subject:RE: Sample Rate Changes While recording

Reply by: Chienworks

Date:9/8/2010 11:19:00 AM

Correct, but recording to mono uses only half the disc space.

Subject:RE: Sample Rate Changes While recording

Reply by: rraud

Date:9/9/2010 11:59:17 AM

"If it's going to be a Red Book CD, the audio is going to be two channels, whether you want them or not"

Yes indeed, on an audio CD, a mono source file still goes to both L & R channels and you will not be able to put more than the usual 74/80 minutes on it as well.