Why WAV for DVD and TV sound
WAV holds plain PCM samples, the form in which audio programs work internally. Converting MPEG to WAV is the usual first step when the sound needs work:
- Restoration. Old VHS tapes digitised to MPG often have hiss, hum or uneven levels. Noise reduction in Audacity or another editor works best on uncompressed audio.
- Mixing and mastering. A concert filmed on a DVD camcorder can be cleaned and balanced in a digital audio workstation.
- Transcription. Many speech-to-text tools prefer WAV input for recorded lectures and meetings.
- Broadcast and archives. WAV is a standard exchange format for radio and audio archives.
PCM tracks: a special case
Some DVDs, especially music and concert discs, and some camcorders store the sound as PCM, which is exactly what a WAV file contains. In that case nothing has to be compressed or re-encoded, and the WAV is a perfect copy of the disc sound. Choosing Original audio in the Save audio as list copies such a track as it is; the tool tells you whether this is possible for your file. MP2 and Dolby Digital tracks are decoded to PCM by the built-in converter engine; nothing further is lost, but their earlier compression remains.
Size and channels
WAV is big: about 10 MB per minute for 16-bit stereo at 44.1 kHz, and more at the 48 kHz used by DVDs. A two-hour DVD concert makes a WAV of more than a gigabyte, so trimming to the part you need saves a lot of disk space. A DVD with 5.1 surround sound has six channels; the tool shows the channel count of your source.
16-bit or 32-bit float
Standard WAV is right for almost all uses. Choose 32-bit float if you plan heavy processing, such as strong gain changes, because it avoids clipping between steps. It doubles the size.
Everything runs in your browser, so recordings stay on your computer. For lossless sound in half the space, use MPEG to FLAC. To listen on a phone, MPEG to MP3 is much smaller.