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9c220a31 LR |
1 | This document is a guide to using the emu10k1 based devices with JACK for low |
2 | latency, multichannel recording functionality. All of my recent work to allow | |
3 | Linux users to use the full capabilities of their hardware has been inspired | |
4 | by the kX Project. Without their work I never would have discovered the true | |
5 | power of this hardware. | |
6 | ||
7 | http://www.kxproject.com | |
8 | - Lee Revell, 2005.03.30 | |
9 | ||
10 | Low latency, multichannel audio with JACK and the emu10k1/emu10k2 | |
11 | ----------------------------------------------------------------- | |
12 | ||
13 | Until recently, emu10k1 users on Linux did not have access to the same low | |
14 | latency, multichannel features offered by the "kX ASIO" feature of their | |
15 | Windows driver. As of ALSA 1.0.9 this is no more! | |
16 | ||
17 | For those unfamiliar with kX ASIO, this consists of 16 capture and 16 playback | |
18 | channels. With a post 2.6.9 Linux kernel, latencies down to 64 (1.33 ms) or | |
19 | even 32 (0.66ms) frames should work well. | |
20 | ||
21 | The configuration is slightly more involved than on Windows, as you have to | |
22 | select the correct device for JACK to use. Actually, for qjackctl users it's | |
23 | fairly self explanatory - select Duplex, then for capture and playback select | |
24 | the multichannel devices, set the in and out channels to 16, and the sample | |
25 | rate to 48000Hz. The command line looks like this: | |
26 | ||
27 | /usr/local/bin/jackd -R -dalsa -r48000 -p64 -n2 -D -Chw:0,2 -Phw:0,3 -S | |
28 | ||
29 | This will give you 16 input ports and 16 output ports. | |
30 | ||
31 | The 16 output ports map onto the 16 FX buses (or the first 16 of 64, for the | |
32 | Audigy). The mapping from FX bus to physical output is described in | |
33 | SB-Live-mixer.txt (or Audigy-mixer.txt). | |
34 | ||
35 | The 16 input ports are connected to the 16 physical inputs. Contrary to | |
36 | popular belief, all emu10k1 cards are multichannel cards. Which of these | |
37 | input channels have physical inputs connected to them depends on the card | |
38 | model. Trial and error is highly recommended; the pinout diagrams | |
39 | for the card have been reverse engineered by some enterprising kX users and are | |
40 | available on the internet. Meterbridge is helpful here, and the kX forums are | |
41 | packed with useful information. | |
42 | ||
43 | Each input port will either correspond to a digital (SPDIF) input, an analog | |
44 | input, or nothing. The one exception is the SBLive! 5.1. On these devices, | |
45 | the second and third input ports are wired to the center/LFE output. You will | |
46 | still see 16 capture channels, but only 14 are available for recording inputs. | |
47 | ||
48 | This chart, borrowed from kxfxlib/da_asio51.cpp, describes the mapping of JACK | |
49 | ports to FXBUS2 (multitrack recording input) and EXTOUT (physical output) | |
50 | channels. | |
51 | ||
52 | /*JACK (& ASIO) mappings on 10k1 5.1 SBLive cards: | |
53 | -------------------------------------------- | |
54 | JACK Epilog FXBUS2(nr) | |
55 | -------------------------------------------- | |
56 | capture_1 asio14 FXBUS2(0xe) | |
57 | capture_2 asio15 FXBUS2(0xf) | |
58 | capture_3 asio0 FXBUS2(0x0) | |
59 | ~capture_4 Center EXTOUT(0x11) // mapped to by Center | |
60 | ~capture_5 LFE EXTOUT(0x12) // mapped to by LFE | |
61 | capture_6 asio3 FXBUS2(0x3) | |
62 | capture_7 asio4 FXBUS2(0x4) | |
63 | capture_8 asio5 FXBUS2(0x5) | |
64 | capture_9 asio6 FXBUS2(0x6) | |
65 | capture_10 asio7 FXBUS2(0x7) | |
66 | capture_11 asio8 FXBUS2(0x8) | |
67 | capture_12 asio9 FXBUS2(0x9) | |
68 | capture_13 asio10 FXBUS2(0xa) | |
69 | capture_14 asio11 FXBUS2(0xb) | |
70 | capture_15 asio12 FXBUS2(0xc) | |
71 | capture_16 asio13 FXBUS2(0xd) | |
72 | */ | |
73 | ||
74 | TODO: describe use of ld10k1/qlo10k1 in conjunction with JACK |