I have a scenario where I am allocating a chunk of data for audio playback. The audio I'm loading from a MOD(XM/FastTracker2 to be specific) sample data. The trick however is that because the sample data is delta encoded for compression reasons, I now have to go byte-by-byte or word-by-word [size=9px](for 16-bit audio)[/size] through the whole thing and run it through a simple decryption algo.
Here is the algo in semi-Pascal:
[pascal]var
old, new: ShortInt;
old := 0;
for i := 0 to data_len do
begin
new := sample[i] + old;
sample[i] := new;
old := new;
end;[/pascal]
Now how would I best access my audio data considering that I originally allocate and dump it like so...
[pascal] {Sample Data}
for j := NumberOfSamples - XmInstrument.NumOfSamples to NumberOfSamples - 1 do
begin
GetMem(Samples[j].SampleData, Samples[j].SampleLength);
BlockRead(FileStream, Samples[j].SampleData^, Samples[j].SampleLength);
end;[/pascal]
I want to maintain my SampleData pointer as it is so that I can then later give this to whatever audio buffer loading function for OpenAL, DSound, etc... Beyond that I can use whatever additional structures I might need.
EDIT: I guess my original question should have been how can I access a specific piece of the data after allocating it via GetMem().
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