More recently, we made QuickTime smart enough to detect ISO padding
and to use "variableCompression" sound media to represent it
accurately. But when trying to make this QuickTime's default
behavior when importing MP3 files we discovered that we broke some
applications. So the 4.1 behavior remains the default. Nevertheless
you can override the default behavior and get accurate sound media
when importing MP3 files, but it's a little tricky and involves
capturing the importer, setting a flag, and then delegating to it.
I'd very much like to make this behavior more accessible (eg, a
property for NewMovieFromProperties), but in the meantime if you
require this behavior in your app now, let me know.
I'm pretty I'm seeing that problem too. I'm using Kurt Revis'
QTSoundFilePlayer code (heavily modified) to play sound files. It
calls GetMediaDuration() to get the media duration, then uses QT to
read in the data and the CoreAudio HAL Output Unit for output. I've
just added code to detect when the ring buffer runs dry and stop
playback when it does. (To prevent the horrible drive-thrashing that
occurs when trying to play two files from a CD at the same time.)
Everything works except that I get a notification of multiple dropped
buffers at the end of MP3 files. I.e. my ring buffer is empty
(because the file was read to the end), but the media duration hasn't
been reached. This appears to be an error in the media duration
returned by GetMediaDuration(). Which sounds like the issue
described above. I'd love to have the correct media length, so as to
avoid creating a lot of false dropout warnings. I'm NSLogging them
right now, but I'd be loth to do that if every MP3 file generates
dropouts.
The second problem, of an unknown number of zeros at the start of the
file, may also apply here, but perhaps it's not as big an issue?
Thanks for any help.
-Kevin
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