Subject:mono to stereo

Posted by: Techno1

Date:2/27/2002 12:36:41 PM

Hi there. I am a student at college at the age of 15.

I do a lot of computer programming and video editing.

I am now doing sound engeneering as a hobby too.

I need help.

I love sound forge. I have downloaded a film and the sound is mono MP3 8 bit 22050Hz. I have striped the audio to a wav file and loaded it in to sound forge v4.5e. I am using Windows 98SE.

Now, I know that 44100Hz is CD quality audio (16bit stereo). I changed the sample freq. to 44100Hz from 22050Hz. The quality is great, but it sounds like chip monks, it's going fast!

How do I keep the same pace of audio but have it better sound? I have done this usinga different tool but for some reason, it doesn't work now so I bought a copy of sound forge and I though it may solve the problem.

After the problem is solved, I thought I could put the audio and video together so they match.

Please help, any advice is greatly appreciated.

Thanks

Techno

Subject:RE: mono to stereo

Reply by: Iacobus

Date:2/27/2002 1:32:22 PM

Did you try using Process>Resample on the menu bar within Sound Forge?

Sounds like you're just setting the sample rate without resampling. When you do that, you change the pitch (and speed) of the original file.

HTH,
Iacobus

Subject:RE: mono to stereo

Reply by: spydakb

Date:2/27/2002 1:33:17 PM

QTools/AX DirectX Plugin - http://www.qsound.com/pro/qtax.asp


I paid about US$30, new, for it at Digibid (seen it there for as low as US$14). It is always being sold there. It does a pretty good job.

KB

Subject:RE: mono to stereo

Reply by: jgalt

Date:2/27/2002 7:56:24 PM

As md said, I believe you checked the wrong box when you elected to resample. Take a look at the resample option. Notice there are 2 boxes. I think you checked the one that says "Change the sample rate only (Do not resample). IF that is what you did, go back to that option. Check this same box again and select a sample rate of 22.05 KHz and run it. When finished, pick the resample option again and THIS TIME check the other box and set your sample rate at 44.1 KHz.

I have forgotten why you wanted to resample but normally there is little or no advantage to doing this and there can be disadvantages.

Subject:RE: mono to stereo

Reply by: jgalt

Date:2/27/2002 8:07:48 PM

I just read your original post again. It is my opinion that merely increasing the sample rate from 22.05 KHz to 44.1 KHz will not, by itself, improve the audio quality of that file. The upper frequency limit of that file has already been set at a maximum of around 11 KHz by the original sample rate and the volume level variations within that file were set by the original 8 bit, bit rate. Unless you plan on doing some heavy frequency equalization to that file, you might be better off leaving it at a sample rate of 22.05 KHz.

Subject:RE: mono to stereo

Reply by: Rednroll

Date:2/28/2002 7:44:38 PM

Yeah, that's correct once you're at a lower sampling rate, sonically it doesn't do you any good to go to a higher sample rate. By the Nyquist thereom if the original file was sampled at 22Khz then the highest frequency you could have recorded was 11Khz, so basically you lost the frequencies from 11Khz to 20Khz, and you can't get them back by resampling.

If you tried to change the sampling rate by changing it under the "properties" command under the file menu, then this does not change the actual sampling rate. It only changes the clock speed that sound forge plays back at, and now it will give that chipmunck sound you're hearing. Set the properties back to the 22050, and then use the "Resample" function under the tools menu, and resample to 44,100. The only thing you will benefit from this though is that you probably have more compatibility playing audio back at 44.1khz with other devices. You get no increase in quality, but you do get twice the file size from the original.

red

Subject:RE: mono to stereo

Reply by: dbarry

Date:2/28/2002 8:53:44 PM

Yes, all is true but..
If you want to make CDs or DVDs or synch audio to vidio, you convert to 44.1 just to be at the "standard" rate. As others have said you don't something for nothing audio but some resampling algorithms actually do spread the engery over a wider spectrum.