Audio Pitch Problem

[Bully9]

I have an avi file and the audio plays one octave below where it should in WMP. No sound at all in MPClassic.

Mediainfo tells me that the audio is 2 channels VBR, but gspot says it's monophonic and if i open the file in goldwave it produces just a mono window.

If i increase the pitch in Goldwave by 100%, the sound is perfect, BUT it is halved in length. I can save this new file and mux it perfectly with the avi in virtualdub, but halfway through of course, the sound runs out. If i increase the pich and "preserve length" the audio sounds horrible.

The really bizarre thing is, i played a few seconds of the avi once in WMP before opening it in goldwave, and i'm sure it played at the correct pitch. But after i extracted the audio in goldwave, the original avi - which i DID NOT modify - now only plays one octave below in WMP!!

I've never come across anything like this before and would be really grateful for any help.

[redwudz]

I would convert it to CBR before you try to do anything with it. I usually save VBR audio out as a WAV with VirtualDub Mod, then work with it in an audio editor. I use Audacity, but Goldwave is likely better.

[Bully9]

Thanks Redwudz, but i don't think you understand the problem.

The reason i extracted the audio was in fact to convert to CBR and remux. The problem is that it plays an octave too low, extracted wav or in the original avi.

What i need to know is how to get it to play at the correct pitch. Maybe something is corrupt in the avi that i can fix?
Or if i need to process the extracted wav, how do i raise the pitch an octave without halving the length? As i said there is a facility in goldwave to do this but the resulting audio is terrible quality.

[Bully9]

Actually, i've noticed that the avi now seems to play at "half speed" in wmp.

If i play it in powerdvd at 2x speed, the video is fine, but the audio still plays an octave low (ie at half speed!)

[AlanHK]

As i said there is a facility in goldwave to do this but the resulting audio is terrible quality.

Audacity has an effect "change pitch" as well.

Anyway, what is the fps of the original AVI?

I once had an AVI that was, I think 15 fps and had similar problems.

I used a script like this:

AVISource("03_Happy.avi")
Changefps(30)
Assumefps(30000,1001,true)
resampleaudio(48000)

which gave a normal sounding audio when extracted with VDub.

[Bully9]

Thanks, i tried messing around with frame rates. It did seem that the media player was playing the audio at half the speed which was clearly causing the pitch problem. I did crack it eventually by demuxing (not saving wav) in virtualdubmod. This i believe erases the header information which was causing the problem when i tried to extract the audio in goldwave, (or save wav in virtualdub) which is the method i normally use with no problems.

Anyway, VDM produced a perfect mp3. which i then opened in goldwave, saved as wav and then remuxed into the original avi using VD in CBR audio. Hope this info may save someone else a few hours!

[redwudz]

I'm not sure if you used 'Full processing' in the audio selection when saving out the WAV with VD Mod, but if not, you can end up with a WAV in a wrapper format of your original audio which can cause problems.