A
[email protected]
- Jan 1, 1970
- 0
I am trying to make an audio playback device which uses a OTP EPROM to
store audio as a specially encoded bitstream (1 bit resolution). The
bit stream is played into an RC low pass filter, and the output is the
original audio signal (plus noise, quantization error, etc.. but more
or less the original). This makes for a very simple audio playback
circuit, which would include a clock, an eprom, and an rc filter. The
"problem" is generating that special 1 bit bitstream from the original
audio signal. I think generating it on a computer and then programming
the bitstream into the EPROM would be a good way to do it. I was
thinking of modelling the response of the RC filter on the computer,
and then for each bit in the bit stream, picking 0 or 1 depending on
which makes the output of the RC filter closer to the original audio
signal. Someone else has done this:
http://www.romanblack.com/picsound.htm
Problem is, his DOS encoder software doesnt work on my computer (I
tried DOSBOX to no avail).
I am experienced in C so I could write my own program, but I am not
sure how to correctly model the RC filter response to a bit stream.
Could someone lead me in the right direction here? I want to be able to
tell the program what bit rate, and what values for R and C, and then
dump a .wav file into it and have it spit out the 1 bit bitstream and
the predicted output of the RC filter (to compare it to the original
file).
Also, is there a way to calculate how big the EPROM needs to be in
order to playback 1 second of audio with a 4096hz bandwidth? (highest
frequency component of signal is about 4 khz).
store audio as a specially encoded bitstream (1 bit resolution). The
bit stream is played into an RC low pass filter, and the output is the
original audio signal (plus noise, quantization error, etc.. but more
or less the original). This makes for a very simple audio playback
circuit, which would include a clock, an eprom, and an rc filter. The
"problem" is generating that special 1 bit bitstream from the original
audio signal. I think generating it on a computer and then programming
the bitstream into the EPROM would be a good way to do it. I was
thinking of modelling the response of the RC filter on the computer,
and then for each bit in the bit stream, picking 0 or 1 depending on
which makes the output of the RC filter closer to the original audio
signal. Someone else has done this:
http://www.romanblack.com/picsound.htm
Problem is, his DOS encoder software doesnt work on my computer (I
tried DOSBOX to no avail).
I am experienced in C so I could write my own program, but I am not
sure how to correctly model the RC filter response to a bit stream.
Could someone lead me in the right direction here? I want to be able to
tell the program what bit rate, and what values for R and C, and then
dump a .wav file into it and have it spit out the 1 bit bitstream and
the predicted output of the RC filter (to compare it to the original
file).
Also, is there a way to calculate how big the EPROM needs to be in
order to playback 1 second of audio with a 4096hz bandwidth? (highest
frequency component of signal is about 4 khz).