AIFC (Python and audio files.)

[Kelvin Chu]

Hello, Python Wizards...

I'm trying to use Python to write an aiff file. I've used the aifc module
and I've set the parameters (# of channels, encoding rate, compression,
etc.)

What does raw audio data look like? Is each word of the raw audio data a
frequency? If I encode 440 for each of the frames, will I get concert A?

Thanks for any advice you can give on this subject.

Best,

-k

--
Kelvin Chu
Department of Physics, Cook Building, 82 University Place
University of Vermont, Burlington, VT 05405-0125
802.656.0064, http://www.uvm.edu/~kchu/

[Erik de Castro Lopo]

Kelvin Chu wrote:

Hello, Python Wizards...

I'm trying to use Python to write an aiff file. I've used the aifc module
and I've set the parameters (# of channels, encoding rate, compression,
etc.)

What does raw audio data look like? Is each word of the raw audio data a
frequency? If I encode 440 for each of the frames, will I get concert A?

AIFC files contain digitally sampled sound, much like the data
stored on a CDROM.

Try looking up PCM (Pulse Code Modulation) on Google for a deeper
explanation.

Erik
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[Dennis Lee Bieber]

Kelvin Chu fed this fish to the penguins on Sunday 13 July 2003 06:34
pm:

What does raw audio data look like? Is each word of the raw audio
data a
frequency? If I encode 440 for each of the frames, will I get concert
A?
So far as I know, aiff is raw waveforms... IE: each data point varies
from -127(8) to +127 (well, actually I think they may use 16bit data
rather than 8bit, you should understand the concept). To get one second
of pure A you will have to encode a sine wave (-1.0..+1.0) scaled to
(-127..+127) into one second's worth of data. Figure out the
samples/second, and work out the relationship to the frequency of the
A...

Of course, you do have the options of using other wave forms -- a sine
wave is rather pure... Maybe you want a square wave?

One of the earliest "synthesizers" I had was a D/A converter on my
TRS-80 Mod III/4 (Orchestra 90, as I recall). The software defined
instruments in terms of relative strengths of harmonics -- a sine wave
was something like F0000000 (full level on primary, 0 on all harmonics).

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[Dennis Lee Bieber]

Dennis Lee Bieber fed this fish to the penguins on Sunday 13 July 2003
08:52 pm:

So far as I know, aiff is raw waveforms... IE: each data point
Whoops, misread your subject... Not sure what aifc differences might
be...

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