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Re: A92: .Wav---->.92p
Grant Stockly wrote:
> The 85 can do 4bit, I would think the 92 should be able to do 8... If
> there are any good programmers in here, maybe you could help me port the
> sound player...
>
> Grant
>
If you would send me the sources of the 85 sound progam, I will see...
(I haven't got a TI-85, but I often programed 80286-asm, and I think
Z80 is the base of all Intel-chips)
I thought of something like this, some time ago, my idea was, to
create more than on-off status of the linkport, by switchin on-on-off
or off-off-on... But I calculated, that 8-bit wouldn't be possible, because
I can only switch on or off the linkport about 65536 times a second.
(this is approximately the time an, assemly loop with some NOPs needs)
4 Bits would mean 16 states, that means 16 switches. This would decrease
the sample rate to 65535/16 = 4096 samples/sec. What means, that the quility
is really low. 8Bit sound would decrease the sample rate to 256 samples/sec,
this is much to less to get sounds be played on the TI-92.
As comparison: The digital ISDN-telephone system uses 9000 samples/second.
If I will decide to program sound for the TI-92, there would appear another
problem: I would have to program two sound libraries, one for 128K TI-92s
and one for 256K TI-92s (or TI-92 II or +), because the 256K version is
faster. (But this doesn't mean, that the 256K TI-92 would enable more
samples,
because the I/O-Ports are as fast as normal)
I think, that I have somewhere a documentation about the .WAV-format so if I
have
time, I will perhaps try to develop a convertion program.
Another alternative for the on-off switching, would be to build a
digital-analog converter,
that is acceeded by the TI-92 linkport, this would give the possibility of
having more
sampels/sec. the TI-92 can transfer about 3K/s, if 4 bits are used to
represent one sample,
a sample rate of about 6K/sec would be achieved. And by the way: Sounds
would be
quite huge, compared with the small memory of the TI-92, so a .WAV
compression
would be neccessary.
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