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Old 1st June 2006, 01:53 AM   #1
Rocky is offline Rocky  Norway
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Question PCM and I2S...

As I gather it, PCM can be expressed in I2S data, but does anyone have some useful information or pointers to information on how the two formats relates? It seems very hard to find any useful documentation on I2S... The PCM I want to express in I2S is 44.1 ksamples/sec, 16 bit, stereo..
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Old 1st June 2006, 04:04 AM   #2
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The data sheets for the DAC chip might be a good place to start. Depending upon the chip, some data sheets are more informative tha others in this regard.

-david
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Old 1st June 2006, 08:52 AM   #3
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The I2S Bus specification.
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Old 1st June 2006, 05:26 PM   #4
Rocky is offline Rocky  Norway
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Quote:
Originally posted by dw8083
The data sheets for the DAC chip might be a good place to start. Depending upon the chip, some data sheets are more informative tha others in this regard.

-david
I'm not aproaching this with any specific DAC chip in mind, if I can successfully translate PCM into *any* I2S, my CPLD can take care of the final logic transformations regardless of which chip I'll be using.

Quote:
Originally posted by rfbrw
The I2S Bus specification.
Excellent

That's the sort of papers I need. Tanks alot.
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Old 1st June 2006, 10:01 PM   #5
Rocky is offline Rocky  Norway
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so, the I2S data line is simply a pulse-coded modulation, but is it signed or unsigned?

Take for example a 16-bit I2S data chunk - will it identify an amplitude with min point 0, max point 65535 (0xFFFF), or will it identify 0 as the mid point, -32768 (-0x8000) as the min point, and 32767 (0x7FFF) as the max point?
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Old 1st June 2006, 10:10 PM   #6
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The format of the I2S data *IS* the PCM.

I2S is the physical interface between the blocks, PCM is the data format.
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Old 1st June 2006, 10:21 PM   #7
Rocky is offline Rocky  Norway
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Quote:
Originally posted by BlackCatSound
The format of the I2S data *IS* the PCM.

I2S is the physical interface between the blocks, PCM is the data format.
Ah, makes sense so it is in fact signed, then.. for 16 bit data at least..? 0x0000 is the mid point?
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Old 2nd June 2006, 08:38 AM   #8
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Quote:
o, the I2S data line is simply a pulse-coded modulation, but is it signed or unsigned?
Signed

ST
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Old 2nd June 2006, 10:35 AM   #9
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Quote:
Originally posted by Rocky


Ah, makes sense so it is in fact signed, then.. for 16 bit data at least..? 0x0000 is the mid point?
Binary Two's complement.
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Old 2nd June 2006, 11:54 PM   #10
Rocky is offline Rocky  Norway
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Thanks alot, rfbrw, BlackCat.

EDIT: and blu_line
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