i have an .avi that i want to strip the audio from and reduce its quality enough that i can fit it on a cd.. current file size is 780 mb. desired size is about 720 mb. can someone tell me how to effectively compress the audio without affecting video????
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Use Virtualdub MP3 Freeze, open the video and select under video->direct stream copy and under audio->full processing and under audio->compression choose mp3 with a lower bitrate. If you can't find mp3 in the compression list install the Lame MP3 ACM Codec . Last hit File->Save AVI. This will not affect the video, only copy it with the new compressed audio.
Converting your audio to MP3 might not be the best choice, since not some standalone DVD players cannot play a VCD with an MPEG-1 layer 3 audio track as opopsed to an MPEG-1 layer 2 audio track. In fact, Nero will give you an error message if you try to burn a VCD or DVD with mp3 audio. It might work...but then again, it might not. Depends on your particular standalone DVD player. It will almost certainly work on your computer if all you want to do is play back your VCD or DVD on your computer.
You might be better off extracting your AVI audio to a WAV and then to Dolby AC3. All standalone DVD players & software computer-based DVD players will play AC3, so that should ensure maximum compatibility.
You can extract the WAV file as Baldrick suggests, or you could open the AVI file with TMPGEnc and choose SAVE AS then WAV (for DVDs make sure the WAV file is spec'd at 384 kbits and 48,000 khz sample rate -- if it uses a different sample rate you must open the WAV file with some audio editing program like Sound Forge XP or GodWave or CoolEdit and resample to 48,000 khz. On the other hand, if you are goping to burn a VCD, then your WAV file must use 44,100 khz sampling rate and 192 kbits data rate.) You should also normalize your WAV file at this point (a typical option available in almost all audio editors, including GodWave, Sound Forge XP, etc.).
Once you have the WAV file at the correct sample rate, go to www.doom9.org and download BeSweet and AC3 Machine (the latter is a GUI front end that makes conversion from WAV to AC3 a piece of cake). Follow the instructions at www.dom9.org and you'll soon find you need only one click to convert your WAV files to AC3.
AC3 compresses the WAV file about as much as MP2 or MP3, give or take, so you should save a LOT of space on your target disk by using AC3. Inside AC3 Machine, remember to check the HEAVY COMPRESSION box and select some boost in the box below that -- I typically use about 18 dB -- because otherwise AC3 tends to sound too low in volume because of its extreme dynamic range.