PCM and I2S...

Rocky · 1st June 2006, 01:53 AM

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..

hifimaker · 1st June 2006, 04:04 AM

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

rfbrw · 1st June 2006, 08:52 AM

The I2S Bus specification.

Rocky · 1st June 2006, 05:26 PM

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.

Rocky · 1st June 2006, 10:01 PM

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?

BlackCatSound · 1st June 2006, 10:10 PM

The format of the I2S data *IS* the PCM.

I2S is the physical interface between the blocks, PCM is the data format.

Rocky · 1st June 2006, 10:21 PM

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?

blu_line · 2nd June 2006, 08:38 AM

Quote:

o, the I2S data line is simply a pulse-coded modulation, but is it signed or unsigned?

Signed

ST

rfbrw · 2nd June 2006, 10:35 AM

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.

Rocky · 2nd June 2006, 11:54 PM

Thanks alot, rfbrw, BlackCat.

EDIT: and blu_line

1st June 2006, 01:53 AM	#1
Rocky diyAudio Member Join Date: Apr 2004 Location: Kongsberg/Oslo	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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1st June 2006, 04:04 AM	#2
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	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

1st June 2006, 08:52 AM	#3
rfbrw diyAudio Member Join Date: Oct 2001 Location: .	The I2S Bus specification.

1st June 2006, 10:01 PM	#5
Rocky diyAudio Member Join Date: Apr 2004 Location: Kongsberg/Oslo	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?

1st June 2006, 10:10 PM	#6
BlackCatSound diyAudio Member Join Date: Oct 2004	The format of the I2S data IS the PCM. I2S is the physical interface between the blocks, PCM is the data format.

2nd June 2006, 11:54 PM	#10
Rocky diyAudio Member Join Date: Apr 2004 Location: Kongsberg/Oslo	Thanks alot, rfbrw, BlackCat. EDIT: and blu_line

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