Writing "interesting" audio formats with AudioFile
Writing "interesting" audio formats with AudioFile
- Subject: Writing "interesting" audio formats with AudioFile
- From: "Timothy J. Wood" <email@hidden>
- Date: Wed, 10 Mar 2004 19:42:31 -0800
I'm able to set up AudioFile to write a LPCM WAV file, but nothing
interesting like AAC or MP3. Are there any examples on this? All the
examples I see in /Developer/Examples/CoreAudio are pretty useless for
compressed audio -- I can only find AIFF and WAV writing there.
I've looked at the stream formats supported for AAC and MP3 as
reported by AudioFileGetGlobalInfo, but it gives nearly useless
information like:
2004-03-10 19:24:07.662 af-global-info[921] 0x61647473 AAC ADTS
<CFArray 0x517b10 [0xa01900e0]>{type = immutable, count = 2, values = (
0 : <CFString 0xa3b5cde4 [0xa01900e0]>{contents = "aac"}
1 : <CFString 0xa3b5cdf4 [0xa01900e0]>{contents = "adts"}
)}
format count: 1
format: 0x61616320
mSampleRate = 0.000000
mFormatID = 0x61616320
mFormatFlags = 0x00000000
mBytesPerPacket = 0
mFramesPerPacket = 0
mBytesPerFrame = 0
mChannelsPerFrame = 1
mBitsPerChannel = 0
mReserved = 0x00000000
If I feed anything like this stream format into AudioFileCreate, I
get a 'fmt?' error.
I replaced the sample rate with 44100.0 and tried tweaking some of
the other values to something reasonable, but I don't know what to set
the packet related stuff to. How are we supposed to know what stream
formats are REALLY valid?
-tim
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