mirror of
https://github.com/torvalds/linux.git
synced 2024-11-13 23:51:39 +00:00
75 lines
3.2 KiB
Plaintext
75 lines
3.2 KiB
Plaintext
|
This document is a guide to using the emu10k1 based devices with JACK for low
|
||
|
|
latency, multichannel recording functionality. All of my recent work to allow
|
||
|
|
Linux users to use the full capabilities of their hardware has been inspired
|
||
|
|
by the kX Project. Without their work I never would have discovered the true
|
||
|
|
power of this hardware.
|
||
|
|
|
||
|
|
http://www.kxproject.com
|
||
|
|
- Lee Revell, 2005.03.30
|
||
|
|
|
||
|
|
Low latency, multichannel audio with JACK and the emu10k1/emu10k2
|
||
|
|
-----------------------------------------------------------------
|
||
|
|
|
||
|
|
Until recently, emu10k1 users on Linux did not have access to the same low
|
||
|
|
latency, multichannel features offered by the "kX ASIO" feature of their
|
||
|
|
Windows driver. As of ALSA 1.0.9 this is no more!
|
||
|
|
|
||
|
|
For those unfamiliar with kX ASIO, this consists of 16 capture and 16 playback
|
||
|
|
channels. With a post 2.6.9 Linux kernel, latencies down to 64 (1.33 ms) or
|
||
|
|
even 32 (0.66ms) frames should work well.
|
||
|
|
|
||
|
|
The configuration is slightly more involved than on Windows, as you have to
|
||
|
|
select the correct device for JACK to use. Actually, for qjackctl users it's
|
||
|
|
fairly self explanatory - select Duplex, then for capture and playback select
|
||
|
|
the multichannel devices, set the in and out channels to 16, and the sample
|
||
|
|
rate to 48000Hz. The command line looks like this:
|
||
|
|
|
||
|
|
/usr/local/bin/jackd -R -dalsa -r48000 -p64 -n2 -D -Chw:0,2 -Phw:0,3 -S
|
||
|
|
|
||
|
|
This will give you 16 input ports and 16 output ports.
|
||
|
|
|
||
|
|
The 16 output ports map onto the 16 FX buses (or the first 16 of 64, for the
|
||
|
|
Audigy). The mapping from FX bus to physical output is described in
|
||
|
|
SB-Live-mixer.txt (or Audigy-mixer.txt).
|
||
|
|
|
||
|
|
The 16 input ports are connected to the 16 physical inputs. Contrary to
|
||
|
|
popular belief, all emu10k1 cards are multichannel cards. Which of these
|
||
|
|
input channels have physical inputs connected to them depends on the card
|
||
|
|
model. Trial and error is highly recommended; the pinout diagrams
|
||
|
|
for the card have been reverse engineered by some enterprising kX users and are
|
||
|
|
available on the internet. Meterbridge is helpful here, and the kX forums are
|
||
|
|
packed with useful information.
|
||
|
|
|
||
|
|
Each input port will either correspond to a digital (SPDIF) input, an analog
|
||
|
|
input, or nothing. The one exception is the SBLive! 5.1. On these devices,
|
||
|
|
the second and third input ports are wired to the center/LFE output. You will
|
||
|
|
still see 16 capture channels, but only 14 are available for recording inputs.
|
||
|
|
|
||
|
|
This chart, borrowed from kxfxlib/da_asio51.cpp, describes the mapping of JACK
|
||
|
|
ports to FXBUS2 (multitrack recording input) and EXTOUT (physical output)
|
||
|
|
channels.
|
||
|
|
|
||
|
|
/*JACK (& ASIO) mappings on 10k1 5.1 SBLive cards:
|
||
|
|
--------------------------------------------
|
||
|
|
JACK Epilog FXBUS2(nr)
|
||
|
|
--------------------------------------------
|
||
|
|
capture_1 asio14 FXBUS2(0xe)
|
||
|
|
capture_2 asio15 FXBUS2(0xf)
|
||
|
|
capture_3 asio0 FXBUS2(0x0)
|
||
|
|
~capture_4 Center EXTOUT(0x11) // mapped to by Center
|
||
|
|
~capture_5 LFE EXTOUT(0x12) // mapped to by LFE
|
||
|
|
capture_6 asio3 FXBUS2(0x3)
|
||
|
|
capture_7 asio4 FXBUS2(0x4)
|
||
|
|
capture_8 asio5 FXBUS2(0x5)
|
||
|
|
capture_9 asio6 FXBUS2(0x6)
|
||
|
|
capture_10 asio7 FXBUS2(0x7)
|
||
|
|
capture_11 asio8 FXBUS2(0x8)
|
||
|
|
capture_12 asio9 FXBUS2(0x9)
|
||
|
|
capture_13 asio10 FXBUS2(0xa)
|
||
|
|
capture_14 asio11 FXBUS2(0xb)
|
||
|
|
capture_15 asio12 FXBUS2(0xc)
|
||
|
|
capture_16 asio13 FXBUS2(0xd)
|
||
|
|
*/
|
||
|
|
|
||
|
|
TODO: describe use of ld10k1/qlo10k1 in conjunction with JACK
|