Audio Sampling Rate Problem

[pdmbutcher]

I have a number of avi files that I would like to join in order to put them on the same dvd-r. I downloaded AVI MPEG RM WMV Joiner to do this, however when I try to join the files there is an error because the audio sampling rates are different. How can I correct this problem? Is there a way to change audio sampling rates of avi files?

thanks,
pdm

[SaSi]

Open each of the AVI files with VirtualDUB.

Since you don't want to modify video, in Video settings select direct stream copy.

For Audio, select Full Processing Mode.

In Compression, select the compression codec you want (e.g. MP3) and the relevant settings, and save each AVI under a new name.
In Audio--> Conversion, select an appropriate resolution and sampling rate, that is suitable for the audio you have. For example, if one audio is 20kHz 16bit mono and others are 44kHz 16bit stereo, it would make sense to convert all into 44kHz-16Bit-Stereo. (Of course, any AVI files with audio settings like the ones you decide as the common settings don't need to be modified!!)

Make sure you use the same settings (for audio) for each file.

Then you can join them, with VirtualDUB if you want.

Of course, since you are at it, make sure that the video settings are also the same. Frame size, codec and frame rate are critical. Since these files have different audio settings, I would be surprised if they had the same video settings.

[pdmbutcher]

thanks for the help, VirtualDub works well. One more question, is there an easy way to change the fps on an avi file using virtualDub, or will you always get an audio/video desynchronization?

thanks,
pdm

[SaSi]

Nicely timed question. I have spent this weekend doing exactly that: NTSC to PAL conversions.

VirtualDUB is able to change the fps. You select Video->Frame Rate and you can change the frame rate to anything you want.

Of course, this will cause audio to go out of sync. If you need to keep them in sync, then you need to speed up or slow down audio.

To convert 23.976 NTSC to PAL, you just need to change the frame rate from 23.976 to 25 and save the AVI. You also save the audio as WAV. Open the WAV with Cooledit Pro or audition or your favourite audio editor that provides a "change pitch/speed" function, and modify the duration by {final FPS} / {Original FPS}. For 23.976 to 25fps, I use a factor of 0,95904. Depending on how your s/w wants this factor, you may need the inverse, i.e. 104.271

Once this is done, open the new AVI in VirtualDUB, select Audio -->WAV Audio, select the modified pitch audio and then save both of them as a new AVI using direct stream copy for video and an appropriate codec for audio (unless you want to keep audio uncompressed).