Yesterday, 03:18 AM
I'll be happy to be shown I'm talking through my hat, but it seems to me that this is close to much ado about nothing.
I decompiled the protodac driver. Looks like the only thing it does is connect to I2S.
As for I2S, the only signals it communicates to the DAC, hence to the Kali Reclocker, are the serial clock (aka the bit clock), the word select (e.g., left or right channel), and the serial data (e.g., the bits).
AIUI, the reclocker strips out the serial clock from the incoming I2S stream. Its I2S output stream consists of a clean clock of the same frequency with the word select and serial data synced to it.
What this would mean is that the only thing which matters for the reclocker is that it can match the incoming serial clock frequencies. These are set by the PCM material being streamed---16 bit/44.1 kHz, etc.
By my calculations, a 45.1584 MHz oscillator can be the basis for all the 16 bit to 32 bit samples at 44.1 kHz to 358.2 kHz sampling rates if one divides the oscillator output by a factor from 2 to 32. Likewise, a 49.152 MHz oscillator would cover the multiples of 48 kHz sampling rates. I assume the 44/48 nomenclature is just marketing simplification.
Similarly, a 22.5792 MHz oscillator can be the basis for all the 16 bit to 32 bit samples at 44.1 kHz to 176.4 kHz sampling rates if one divides by a factor of 2 to 16. Likewise, a 24.576 MHz oscillator for multiples of 48 kHz sampling rates. Hence, the 22/24 nomenclature.
I see no reason why the 22/24 board would not function correctly with moOde on a Pi unless one selected incorrect options.
Regards,
Kent
I decompiled the protodac driver. Looks like the only thing it does is connect to I2S.
As for I2S, the only signals it communicates to the DAC, hence to the Kali Reclocker, are the serial clock (aka the bit clock), the word select (e.g., left or right channel), and the serial data (e.g., the bits).
AIUI, the reclocker strips out the serial clock from the incoming I2S stream. Its I2S output stream consists of a clean clock of the same frequency with the word select and serial data synced to it.
What this would mean is that the only thing which matters for the reclocker is that it can match the incoming serial clock frequencies. These are set by the PCM material being streamed---16 bit/44.1 kHz, etc.
By my calculations, a 45.1584 MHz oscillator can be the basis for all the 16 bit to 32 bit samples at 44.1 kHz to 358.2 kHz sampling rates if one divides the oscillator output by a factor from 2 to 32. Likewise, a 49.152 MHz oscillator would cover the multiples of 48 kHz sampling rates. I assume the 44/48 nomenclature is just marketing simplification.
Similarly, a 22.5792 MHz oscillator can be the basis for all the 16 bit to 32 bit samples at 44.1 kHz to 176.4 kHz sampling rates if one divides by a factor of 2 to 16. Likewise, a 24.576 MHz oscillator for multiples of 48 kHz sampling rates. Hence, the 22/24 nomenclature.
I see no reason why the 22/24 board would not function correctly with moOde on a Pi unless one selected incorrect options.
Regards,
Kent
