sf adding noise -Sound Forge - PC - MAGIX Community Forums Archive

Subject:sf adding noise Posted by: echataig Date:5/9/2003 2:59:12 AM I load files in riff format and I modify them. When I save the modified audio files in u-law 8khz 8bits, a unwanted noise is automatically added at the end of the signal. What can I do to avoid this unpleasant effect? Thanks in advance for response
Subject:RE: sf adding noise Reply by: MarkWWW Date:5/9/2003 1:23:25 PM I'm guessing that you are getting this unwanted noise when you play back the u-LAW file with something other than Sound Forge? If I'm correct you'll find that you don't get this noise when you play these files in Sound Forge. The reason (assuming I'm correct) is that whatever aplication you're using to play the u-LAW files with is incorrectly assuming that everything from the start of the data in the .WAV file to the end of the file is audio data. This is not necessarily the case - the file may contain additional chunks after the audio data chunk. If the player erroneously assumes that these chunks are part of the audio data and tries to play them as audio data you will get a nasty splat at the end of the file. Two possible solutions: 1. Don't use a player that makes this possibly incorrect assumption - use one that properly understands how to play just the audio data in the data chunk. 2. Ensure that the files you are creating don't have any other chunks after the audio data chunk that will confuse your player. You can do this by making sure that the "Save metadata with file" box is unchecked when you save the data as a u-LAW file. I'm guessing that you are stuck with some oddball player (possibly hardware) and can't use anything else. In which case solution 2 should sort you out. (Assuming I'm right about the cause of the problem of course.) Mark
Subject:RE: sf adding noise Reply by: Geoff_Wood Date:5/9/2003 5:25:58 PM Are you sure the unwanted noise isn't just the inherent crappy sound of an 8 bit signal ? geoff
Subject:RE: sf adding noise Reply by: Rednroll Date:5/9/2003 8:27:56 PM "Are you sure the unwanted noise isn't just the inherent crappy sound of an 8 bit signal ? " Very well possible indeed, especially if the end of the file you're talking about is doing a fade out. 8 bits aren't very good in reporducting a nice clean fade out.
Subject:RE: sf adding noise Reply by: echataig Date:5/13/2003 8:54:18 AM Thanks everyone, support resolved my problem.

Subject:sf adding noise

Posted by: echataig

Date:5/9/2003 2:59:12 AM

I load files in riff format and I modify them.
When I save the modified audio files in u-law 8khz 8bits, a unwanted noise is automatically added at the end of the signal.

What can I do to avoid this unpleasant effect?

Thanks in advance for response

Subject:RE: sf adding noise

Reply by: MarkWWW

Date:5/9/2003 1:23:25 PM

I'm guessing that you are getting this unwanted noise when you play back the u-LAW file with something other than Sound Forge? If I'm correct you'll find that you don't get this noise when you play these files in Sound Forge.

The reason (assuming I'm correct) is that whatever aplication you're using to play the u-LAW files with is incorrectly assuming that everything from the start of the data in the .WAV file to the end of the file is audio data. This is not necessarily the case - the file may contain additional chunks after the audio data chunk. If the player erroneously assumes that these chunks are part of the audio data and tries to play them as audio data you will get a nasty splat at the end of the file.

Two possible solutions:

1. Don't use a player that makes this possibly incorrect assumption - use one that properly understands how to play just the audio data in the data chunk.

2. Ensure that the files you are creating don't have any other chunks after the audio data chunk that will confuse your player. You can do this by making sure that the "Save metadata with file" box is unchecked when you save the data as a u-LAW file.

I'm guessing that you are stuck with some oddball player (possibly hardware) and can't use anything else. In which case solution 2 should sort you out. (Assuming I'm right about the cause of the problem of course.)

Mark

Subject:RE: sf adding noise

Reply by: Geoff_Wood

Date:5/9/2003 5:25:58 PM

Are you sure the unwanted noise isn't just the inherent crappy sound of an 8 bit signal ?

geoff

Subject:RE: sf adding noise

Reply by: Rednroll

Date:5/9/2003 8:27:56 PM

"Are you sure the unwanted noise isn't just the inherent crappy sound of an 8 bit signal ? "

Very well possible indeed, especially if the end of the file you're talking about is doing a fade out. 8 bits aren't very good in reporducting a nice clean fade out.

Subject:RE: sf adding noise

Reply by: echataig

Date:5/13/2003 8:54:18 AM

Thanks everyone,
support resolved my problem.