Raspberry Pi: I2S Fundamental issues!

[Eldam]

Maybe I've confused you: I run the Squeezebox software on the Pi. And I don't use a USB DAC anymore (see our discussion over at Ian's FIFO thread). I use a HifiBerry Digi+ to go S/PDIF to my dCS Puccini.

And I'm currently building the setup with RPi (running Squeezeplug) > Ian's FIFO > S/PDIF out > dCS Puccini.
If I could only find the time to finish this

Ah ye, I got it, now I remember : despite the fifo and isolator for the Pi noise, you will have this problem of reintroducing jitter by a spidf multiplexing again ! Much more complicate for you ! You have also this problem of impedance between the 50 ohms of the i2S and the 75 ohms of the further spidf line !

sorry for the OT !

 

[Fio]

At reboot you will get only noise because rune overwrite mpd.conf, so you must re-edit manually it.

chattr +i ?

 

[davidevinavil]

chattr +i ?

Don't understand your replay but using volumio 1.51 edited mpd.conf stay after reboot

 

[mogle]

I've switch to runeaudio alpha 0.3
Got working 16 and 24 bit music selecting HifyBerry dac and adding format "*:24:*" to /etc/mpd.conf.

then kill and restary mpd with

sudo mpd --kill
mpd

At reboot you will get only noise because rune overwrite mpd.conf, so you must re-edit manually it.

This force 24 Bit even on 16 Bit music so clock is always 64 fs leaving sample freq and channel as original

My output config is

audio_output {
name "snd_rpi_hifiberry_dac"
type "alsa"
device "hw:1,0"
auto_resample "no"
auto_format "no"
format "*:24:*"
enabled "yes"
}

Remember my dac is a pcm1794a NOS like dddac

There's anohter driver for 1794, it's name should be rpi-dac something like that.
It's better for 1794 chip, and you do not need to add resample in config file.
It will output 24bit iis with 16bit source in driver.
Or you can modify driver code & recompile kernel to support it.

 

[davidevinavil]

If I use RPI-DAC can't select output device. Don't know why but the only driver that give output is HifiBerry.
Perhaps I think 24 bit are bit perfect and also 16 bit because the last 8 bit are zero using format "*:24:*"