[Linuxsampler-devel] stereo samples format in DLS2/GIG ?

[<be...@ga...>]

Hi, I was just wondering if Christian, Josh or others
could enlighten me how stereo stamples are stored in DLS2 / GIG files.

Are they stored as a single interleaved stereo sample or 
as two separate mono samples where the first is mapped to the
left output channel while the second to the right channel ?
Treating stereo samples as two mono samples has the 
advantage that you can set different loop points, modulation etc stuff.

Regarding the sample sizes: I've seen only GIG files with 16bit
samples in in them so far. Is 24bit possible ? If yes, how
are they stored ? 24-bit packed ? (which means 3 32 bit words
store 4 24 bit samples).
In order to read these 24bit samples from disk efficiently (in large 
chunks) probably we would need a temporary buffer because 
the streaming ringbuffers (which in case of 16bit samples are arrays
of 16bit quantities (=short datatype)), cannot easily cope
with 3-bytes long (24bit) quantities.
Ok they can (the ringbuffer.h template class can handle any kind
of datatype so just define sample_24bit_t as char[3].
But I guess in order to not incur into CPU read/write penalties
because usually the x86 needs 32bit-aligned read/writes to be able
to work with the maximum efficientcy,
we whould just fit the 24bit samples into 32bit words.

Or am I wrong about the read/write alignement issues ?

thoughts ?

Benno


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