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Building an open embedded audio applicance.

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miero

Member
Joined 2011
I've successfully tested I2S on Buffalo 3 with RPi. It plays very well and up to 192/24 when resampling is not used.

But I was not able to play anything at higher rate than 192kHz or depth 32bits. Are you sure this should work? If yes please check the output of following command during the play:

# cat /proc/asound/card0/pcm0p/sub0/hw_params
access: RW_INTERLEAVED
format: S24_LE
subformat: STD
channels: 2
rate: 192000 (192000/1)
period_size: 1024
buffer_size: 8192
 
Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
Miero, just some quick tips for your setup. Keep the PCM wires very short and do not cross power supply lines nor analog lines. If you have a longer distance to cover you can use a pair of teleporters. My setup is clean both with and without teleporters, but if I had to go more than 10cm or so I would definitely use the teleporters. You have to remember when measuring mixed signal devices to be sure to isolate the measurements gear itself from external influences like ground bounce. Also Legato does not use an aggressive filter for HF/VHF, so you will always see some quantization noise at the output. Your previous reports make me think there could be something wrong in your setup. You definitely should not get any noise between songs. I am happy working with you but if you want one on one help you may want to open a thread on our support forum with pictures etc. That way a longer discussion on your particulars does not distract from progress on this thread. If we learn anything useful to our task we can share it at that time. I deleted a bunch of posts just to clean the topic up.
 
Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
DQ828 said:
In all my time on the internet I've never seen a thread where your posts get removed because the owner (for sake of a better term) doesn't like them, even though they are perfectly valid. Reminds me of Chinese government censorship.
Click to expand...

I have no intent to censor, I only wanted to move the conversation to a more appropriate thread. Relax. :)
 
N

Narla

Member
Joined 2008
Russ - for the lay people in the audience (me!) do you plan to provide a plug and play product that can link to the I2S input of Buffalo two DAC? At present I have a hard drive full of music connected via USB to computer into USB/SPDIF interface then to Buff. I was waiting for your proposed USB to I2S board - but am certainly open to this new innovation.
 
A

AudioLapDance

Member
Joined 2003
Russ White said:
...
Using the raspberry pi with the B3SE is very simple. I have tested two scenarios - each with distinct advantages.

First pi -> DAC direct.
This is really simple:

just wire P5 to the DAC appropriately - as show in the attached picture. Pin 1 is indicated on the rpi by the square pin. And P5 is located right next to P1 (directly below with P1 oriented at the top).

The best news is once configured you can use the pi as an airplay receiver (with a mac) for audio (at 44.1khz) and as a direct audio appliance at up to 192/32bit sample rate (the limit of ALSA at the moment).

I have mine streaming directly from NAS (an ASUS RT-AC66U with a USB SSD drive) at up to 192Khz sounding superb! No complaints. The sound is incredible.
...
Click to expand...

Wow, this is incredible! Forgive all my newb questions (although this seems perfect for a newb willing to learn a bit).

Almost all of my music is flac from CD (44.1/16).

You mentioned your ASUS RT-AC66U with a USB SSD drive. Will this work with any newer router and any USB storage--I have a TL-WR1043ND router and a 1Tb WD Passport ext-hd (not SSD)?

You mentioned "you can use the pi as an airplay receiver (with a mac) for audio (at 44.1khz) and as a direct audio appliance at up to 192/32bit sample rate (the limit of ALSA at the moment)"

Does an 'airplay receiver' allow you to choose music files (flac from CD) and control volume? That's all I really need, what hardware do I need to do that? Can I use a PC (maybe with a special program to emulate MAC)?

Where can you get the cheapest Raspberry Pi or Beaglebone?

I was particularly impressed when Goto said:
Goto said:
...
The benefits of using something like a Pi or a Beaglebone is that they don't run a million housekeeping threads, don't have noisey and complex legacy architectures, make easily managed demands on power and - most importantly - output audio on an inherently low jitter I2S header. This means that you are not contending with USB jobs, or worrying about the various buffers involved in asynch usb audio, nor deriving a clock ref from a noisy SPDIF interface. And you can mount your dac and the computing board so close together that you don't have to worry so much about RFI and other electrical gremlins
...
Click to expand...

Make sense to this streaming-audio newb :D

Thanks for your help,
Cheers,
Jeff
 
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