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Q I am developing code which allows users to mix an additional
sound into the sound track of a QuickTime movie playing under Windows. Since this
cannot be accomplished when the CD- ROM is mastered -- the placement of the sound effect
must be controlled by the user -- I am extracting the sound samples from the QuickTime movie
and blending them with a WAV file which contains the sound effect.
While testing this technique using one of the sample movies from the QuickTime
for Windows beta CD- ROM, I discovered that the SoundDescription record returned by
GetMediaSample contained the constant 'sowt' in the dataFormat field.
The only three formats documented in the QuickTime documentation are raw, MAC3,
and MAC6. I need to know what the format of the 'sowt' samples is so I can mix
them with the WAV samples.
A You're reading the byte backwards. 'sowt' is actually 'twos',
which means that the values of the samples go from a minimum point to a maximum point,
unlike the raw format, which has a binary offset from zero. In all other aspects,
'twos' and 'raw' samples are the same.
[May 01 1995]
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