Re: FLLR (compression ?) in AIFF file
Re: FLLR (compression ?) in AIFF file
- Subject: Re: FLLR (compression ?) in AIFF file
- From: Stephen Davis <email@hidden>
- Date: Tue, 5 Aug 2008 23:08:19 -0700
The FLLR chunk is added by the AudioFile code to align the data chunk
on a 4K page boundary for optimized I/O during playback.
The AIFF specification says to ignore chunks you don't recognize and
skip over them. This is such a chunk. :-)
As for the NONE chunk, it is not a separate chunk but is found in the
"compressionType" field of the COMM chunk.
hth,
stephen
On Aug 5, 2008, at 10:27 PM, Francois Baronnet wrote:
Hi,
using some code provided by Apple to record audio
(http://developer.apple.com/documentation/MusicAudio/Conceptual/AudioQueueProgrammingGuide/AQRecord/chapter_3_section_6.html
),
I'm able to create AIFF files.
Now I want to read thoses files using some code found on this mailing
list (http://lists.apple.com/archives/coreaudio-api/2003/Feb/msg00244.html
).
It doesn't work for me :)
When I open my file using hexadecimal editor, I can see the "FORM",
"AIFF" and "COMM" headers. But I can't find the "NONE" one saying
there is no compression. That's why above objective-C routine can't
work. Instead of "NONE", there is "FLLR". And there is no such header
in AIFF format specification...
If I record my file as AIFC, the begining of the file is different but
still with "FLLR".
Here are my settings for AIFF file:
aqData.mDataFormat.mFormatID = kAudioFormatLinearPCM;
aqData.mDataFormat.mSampleRate = 44100.0;
aqData.mDataFormat.mChannelsPerFrame = 2;
aqData.mDataFormat.mBitsPerChannel = 16;
aqData.mDataFormat.mBytesPerPacket =
aqData.mDataFormat.mBytesPerFrame =
aqData.mDataFormat.mChannelsPerFrame * sizeof (SInt16);
aqData.mDataFormat.mFramesPerPacket = 1;
AudioFileTypeID fileType = kAudioFileAIFFType;
aqData.mDataFormat.mFormatFlags =
kLinearPCMFormatFlagIsBigEndian
| kLinearPCMFormatFlagIsSignedInteger
| kLinearPCMFormatFlagIsPacked;
Thanks for reading me.
--
François Baronnet
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