Re: extended80?
Re: extended80?
- Subject: Re: extended80?
- From: Hidetomo Katsura <email@hidden>
- Date: Mon, 7 Aug 2006 22:50:41 -0700
hi Paul,
i have my own AIFF write (no read) code (i didn't know about
AudioFile stuff when i wrote it...) and according to my experiment on
both ppc and i386, extened80 uses big-endian even on i386. that's
probably because it's not one of C language native value types such
as int, long, float, double, and you always need to treat it as
struct. and you use x80tod() and dtox80() to convert it to a value.
MacTypes.h
Float80 80 bit MacOS float: 1 sign bit, 15 exponent bits, 1
integer bit, 63 fraction bits
typedef Float80 extended80;
fp.h
extern double x80tod(const extended80 * x80);
extern void dtox80(const double *x, extended80 *x80);
i'm not sure how you get "ND" in what type of variable but you are
probably using a 16-bit variable somewhere accidentally.
SoundDataChunk sound; // CarbonCore/AIFF.h
unsigned long ckID;
bool isSoundData;
sound.ckID = EndianU32_NtoB( SoundDataID ); // write
ckID = EndianU32_BtoN( sound.ckID ); // read
isSoundData = ( ckID == SoundDataID );
extened80 is supposed to be 80-bit (10-byte). as long as you use the
types defined in CarbonCore/AIFF.h, it shouldn't get misaligned (or
incorrectly aligned) when you read/write from/to chunk headers.
regards,
katsura
On Aug 7, 2006, at 10:16 PM, Paul Fredlein wrote:
Hi,
I'm attempting to parse, into a AudioBuffer, an aiff file which has
been completely read into an NSData object. I'm having trouble
making sense of the extended80 sample rate in the common chunk. How
do I endian flip an extended80?
I also seem to be having trouble reading it as well as when I read
the chunk type ID in the following sound data chunk I only get an
"ND" instead of a "SNND". (extended80 seems to be 8 bytes but I
thought it was supposed to be 10 bytes.) Is there something about
byte alignment going on here?
I'm on an Intel iMac trying to make a universal binary.
Thanks,
Paul
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| | >extended80? (From: Paul Fredlein <email@hidden>) |