Search found 59 matches

by robiwan
Sun Mar 25, 2018 6:41 pm
Forum: Stereo soundcard for the Raspberry Pi
Topic: I2S
Replies: 2
Views: 1899

Re: I2S

For the Octocard, is the I2S subsystem setup for 8 input/output channel TDM ? It's not obvious from the BCM docs that it is even possible, quite the contrary.
by robiwan
Sat Feb 10, 2018 7:10 pm
Forum: Stereo soundcard for the Raspberry Pi
Topic: Lowest possible latency
Replies: 42
Views: 20337

Re: Lowest possible latency

Just tested fs 96000 Hz with 32 frames which gives ~50% CPU to just shuffle audio from input to output, but I expect the total latency to be below 1 ms, or just there about. For my application 48K is enough, and 64 frames gives ~10% CPU which is a reasonable CPU/latency compromise.
by robiwan
Tue Feb 06, 2018 6:53 pm
Forum: Stereo soundcard for the Raspberry Pi
Topic: Lowest possible latency
Replies: 42
Views: 20337

Re: Lowest possible latency

guysoft, I could actually use some help. I'm sending a PM.
by robiwan
Thu Feb 01, 2018 6:24 am
Forum: Stereo soundcard for the Raspberry Pi
Topic: Lowest possible latency
Replies: 42
Views: 20337

Re: Lowest possible latency

Will do, so far, everything seems to work as expected. Mind you, I've updated my answer with point 5, about systemd thrashing /dev/shm upon logout. Really nasty.
by robiwan
Wed Jan 31, 2018 3:48 pm
Forum: Stereo soundcard for the Raspberry Pi
Topic: Lowest possible latency
Replies: 42
Views: 20337

Re: Lowest possible latency

I had to... 1. Make sure there is large enough shared memory for jack2. Check with df -h : pi@realtimepi:~ $ df -h Filesystem Size Used Avail Use% Mounted on /dev/root 29G 1.6G 26G 6% / devtmpfs 459M 0 459M 0% /dev tmpfs 464M 72K 464M 1% /dev/shm ... If /dev/shm should have a Size of < 128 MB, add t...
by robiwan
Tue Jan 30, 2018 11:52 pm
Forum: Stereo soundcard for the Raspberry Pi
Topic: jackd: Raspberry Pi and Audioinjector
Replies: 8
Views: 8430

Re: jackd: Raspberry Pi and Audioinjector

Ok, I built jack2 from source without dbus, and with the RT patched kernel from https://github.com/guysoft/RealtimePi (thanks guysoft) I can now run the Octocard with frames down to 32 (haven't tried lower) without a hitch. Very happy :) start_jack: #!/bin/sh # Running 64 frames mostly to hold CPU u...
by robiwan
Tue Jan 30, 2018 11:44 pm
Forum: Stereo soundcard for the Raspberry Pi
Topic: Lowest possible latency
Replies: 42
Views: 20337

Re: Lowest possible latency

Thanks guysoft, I've setup a low latency streaming application with your RT image + jack2 + Octocard. It's magic :D
by robiwan
Mon Jan 29, 2018 11:19 pm
Forum: Stereo soundcard for the Raspberry Pi
Topic: How to setup and test
Replies: 130
Views: 180861

Re: How to setup and test

I see. I would suspect that snd_soc_bcm2835_i2s is always needed, since it is the I2S driver, the other drivers merely use I2C to talk to f.i. the WM8731 chipset of the stereo sound card. I.e. I don't think there is a AI specific I2S driver. The dtparam=audio=off stuff is for the PWM audio only. I h...
by robiwan
Mon Jan 29, 2018 9:36 pm
Forum: Stereo soundcard for the Raspberry Pi
Topic: How to setup and test
Replies: 130
Views: 180861

Re: How to setup and test

Here is output from lsmod on my Pi3B on Raspbian Stretch: Looks to me like config.txt is being ignored and the broadcom sound soc is getting loaded despite #dtparam=audio=off in config.txt. Web search returns raspi-blacklist.conf is deprecated, is that true? You do mean dtparam=audio=off, don't you...
by robiwan
Sat Jan 27, 2018 7:50 pm
Forum: Stereo soundcard for the Raspberry Pi
Topic: jackd: Raspberry Pi and Audioinjector
Replies: 8
Views: 8430

Re: jackd: Raspberry Pi and Audioinjector

I'm trying to setup jackd running with the Octocard. I've setup the I2S mmap for /boot/config, but I just can't get the damn jackd server to start: jackdmp 1.9.11 Copyright 2001-2005 Paul Davis and others. Copyright 2004-2014 Grame. jackdmp comes with ABSOLUTELY NO WARRANTY This is free software, an...