Thank you guys!
I'll check out the AudioExtractionPanel right away!
Best regards
Sebastian Probst Eide
On 24. aug. 2005, at 23.31, Daniel Steinberg wrote:
At 1:43 PM -0700 8/24/05, Gen Kiyooka wrote:
>There is a sample "ConvertMovieSoundTrack" which demonstrates
how to read audio from movies and
recompress it. If you want RAW, recompress it to NONE. You can
open pretty much any audio file
as a Movie, but I'm not sure which types allow access as per
ConvertMovieSoundTrack.
There are several reasons why MovieAudioExtraction is far superior
to this technique:
1) You get all the audio data from the movie, mixed together even
if it is spread across multiple tracks.
2) The example uses the SoundManager SoundConverter interface.
This will limit you to audio formats for which there is an sdec/
scom, and eliminates all high-res audio (eg, >2 channels, >65535
Hz). The SoundManager is on its way out, and the CoreAudio
AudioConverter, using adec/aenc codec components, is the Wave Of
The Present.
3) GetMediaSample() is not guaranteed to give you a useful packet
of data in all circumstances, particularly with some weirdo
imported formats that we've managed to finesse internally to play
correctly.
MovieAudioExtraction will deliver any audio data that we're able to
successfully decode and play, in uncompressed format suitable for
signal processing, mixed to the output channel layout you're
interested in, so you don't even have to go down into CoreAudio
unless you want to use AudioUnits or do compression.
>Won't that limit his Application to Tiger and Panter/QT7 systems?
Well, QuickTime 7 systems, on all its current and future platforms.
But, as the saying goes: Time Marches On, and so does QuickTime.
Daniel Steinberg
QuickTime Engineering
>The audio files are most likely going to be compressed as m4a
and MP3, so I thought the easiest thing would be to let
Quicktime do the decompressing of the files and supply me with
the raw data!?
You want to use the new MovieAudioExtraction APIs to get your
raw, decompressed audio samples.
The AudioExtractionPanel code example at <http://
developer.apple.com/samplecode/QTAudioExtractionPanel/
QTAudioExtractionPanel.html > provides a good example of using
the MovieAudioExtraction APIs.
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