1 ==============================================
2 Guide to using M-Audio Audiophile USB with ALS
3 ==============================================
4
5 v1.5
6
7 Thibault Le Meur <Thibault.LeMeur@supelec.fr>
8
9 This document is a guide to using the M-Audio
10 ALSA and JACK.
11
12 History
13 =======
14
15 * v1.4 - Thibault Le Meur (2007-07-11)
16
17 - Added Low Endianness nature of 16bits-mode
18 found by Hakan Lennestal <Hakan.Lennestal@b
19 - Modifying document structure
20
21 * v1.5 - Thibault Le Meur (2007-07-12)
22 - Added AC3/DTS passthru info
23
24
25 Audiophile USB Specs and correct usage
26 ======================================
27
28 This part is a reminder of important facts abo
29 of the device.
30
31 The device has 4 audio interfaces, and 2 MIDI
32
33 * Analog Stereo Input (Ai)
34
35 - This port supports 2 pairs of line-level
36 - When the 1/4" TS (jack) connectors are co
37 are disabled
38
39 * Analog Stereo Output (Ao)
40 * Digital Stereo Input (Di)
41 * Digital Stereo Output (Do)
42 * Midi In (Mi)
43 * Midi Out (Mo)
44
45 The internal DAC/ADC has the following charact
46
47 * sample depth of 16 or 24 bits
48 * sample rate from 8kHz to 96kHz
49 * Two interfaces can't use different sample de
50
51 Moreover, the Audiophile USB documentation giv
52 Please exit any audio application running be
53
54 Due to the USB 1.1 bandwidth limitation, a lim
55 activated at the same time depending on the au
56
57 * 16-bit/48kHz ==> 4 channels in + 4 channels
58
59 - Ai+Ao+Di+Do
60
61 * 24-bit/48kHz ==> 4 channels in + 2 channels
62 or 2 channels in + 4 channels out
63
64 - Ai+Ao+Do or Ai+Di+Ao or Ai+Di+Do or Di+Ao
65
66 * 24-bit/96kHz ==> 2 channels in _or_ 2 chann
67
68 - Ai or Ao or Di or Do
69
70 Important facts about the Digital interface:
71 --------------------------------------------
72
73 * The Do port additionally supports surround-
74 though I haven't tested it under Linux
75
76 - Note that in this setup only the Do inter
77
78 * Apart from recording an audio digital strea
79 to synchronize the device to an external sa
80
81 - As a consequence, the Di port must be ena
82 source is connected
83 - Enabling Di when no digital source is con
84 synchronization error (for instance sound
85
86
87 Audiophile USB MIDI support in ALSA
88 ===================================
89
90 The Audiophile USB MIDI ports will be automati
91 following modules have been loaded:
92
93 * snd-usb-audio
94 * snd-seq-midi
95
96 No additional setting is required.
97
98
99 Audiophile USB Audio support in ALSA
100 ====================================
101
102 Audio functions of the Audiophile USB device a
103 module. This module can work in a default mode
104 parameter), or in an "advanced" mode with the
105 ``device_setup``.
106
107 Default Alsa driver mode
108 ------------------------
109
110 The default behavior of the snd-usb-audio driv
111 capabilities at startup and activate the requi
112 by the applications: for instance if the user
113 24bit-depth-mode and immediately after wants t
114 the snd-usb-audio module will reconfigure the
115
116 This approach has the advantage to let the dri
117 rates/depths automatically according to the us
118 are using the device under windows know that t
119 work: under windows applications must be close
120 panel to switch the device working mode. Thus
121 Default Alsa driver mode can lead to device mi
122
123 Let's get back to the Default Alsa driver mode
124 Audiophile interfaces are mapped to alsa pcm d
125 way (I suppose the device's index is 1):
126
127 * hw:1,0 is Ao in playback and Di in capture
128 * hw:1,1 is Do in playback and Ai in capture
129 * hw:1,2 is Do in AC3/DTS passthrough mode
130
131 In this mode, the device uses Big Endian byte-
132 supported audio format are S16_BE for 16-bit d
133 24-bits depth mode.
134
135 One exception is the hw:1,2 port which was rep
136 compliant (supposedly supporting S16_LE) but p
137 This has been fixed in kernel 2.6.23 and above
138 is reported to be big endian in this default d
139
140 Examples:
141
142 * playing a S24_3BE encoded raw file to the A
143
144 % aplay -D hw:1,0 -c2 -t raw -r48000 -fS24_
145
146 * recording a S24_3BE encoded raw file from
147
148 % arecord -D hw:1,1 -c2 -t raw -r48000 -fS
149
150 * playing a S16_BE encoded raw file to the Do
151
152 % aplay -D hw:1,1 -c2 -t raw -r48000 -fS16_
153
154 * playing an ac3 sample file to the Do port::
155
156 % aplay -D hw:1,2 --channels=6 ac3_S16_BE_e
157
158 If you're happy with the default Alsa driver m
159 issue with this mode, then you can skip the fo
160
161 Advanced module setup
162 ---------------------
163
164 Due to the hardware constraints described abov
165 by the Alsa driver in default mode may result
166 device. For instance, a particularly annoying
167 from the Ai interface sounds distorted (as if
168 volume gain).
169
170 For people having this problem, the snd-usb-au
171 parameter called ``device_setup`` (this parame
172 release 2.6.17)
173
174 Initializing the working mode of the Audiophil
175 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
176
177 As far as the Audiophile USB device is concern
178 specify:
179
180 * the sample depth
181 * the sample rate
182 * whether the Di port is used or not
183
184 When initialized with ``device_setup=0x00``, t
185 the same behaviour as when the parameter is om
186 Alsa driver mode" above)
187
188 Others modes are described in the following su
189
190 16-bit modes
191 ~~~~~~~~~~~~
192
193 The two supported modes are:
194
195 * ``device_setup=0x01``
196
197 - 16bits 48kHz mode with Di disabled
198 - Ai,Ao,Do can be used at the same time
199 - hw:1,0 is not available in capture mode
200 - hw:1,2 is not available
201
202 * ``device_setup=0x11``
203
204 - 16bits 48kHz mode with Di enabled
205 - Ai,Ao,Di,Do can be used at the same time
206 - hw:1,0 is available in capture mode
207 - hw:1,2 is not available
208
209 In this modes the device operates only at 16bi
210 the devices where reported to be Big-Endian wh
211 so that playing a file was a matter of using:
212 ::
213
214 % aplay -D hw:1,1 -c2 -t raw -r48000 -fS16_
215
216 where "test_S16_LE.raw" was in fact a little-e
217
218 Thanks to Hakan Lennestal (who discovered the
219 these modes) a fix has been committed (expecte
220 Alsa now reports Little-Endian interfaces. Thu
221 using:
222 ::
223
224 % aplay -D hw:1,1 -c2 -t raw -r48000 -fS16_
225
226
227 24-bit modes
228 ~~~~~~~~~~~~
229
230 The three supported modes are:
231
232 * ``device_setup=0x09``
233
234 - 24bits 48kHz mode with Di disabled
235 - Ai,Ao,Do can be used at the same time
236 - hw:1,0 is not available in capture mode
237 - hw:1,2 is not available
238
239 * ``device_setup=0x19``
240
241 - 24bits 48kHz mode with Di enabled
242 - 3 ports from {Ai,Ao,Di,Do} can be used at
243 - hw:1,0 is available in capture mode and a
244 connected to Di
245 - hw:1,2 is not available
246
247 * ``device_setup=0x0D`` or ``0x10``
248
249 - 24bits 96kHz mode
250 - Di is enabled by default for this mode bu
251 to an active source
252 - Only 1 port from {Ai,Ao,Di,Do} can be use
253 - hw:1,0 is available in captured mode
254 - hw:1,2 is not available
255
256 In these modes the device is only Big-Endian c
257 mode" above for an aplay command example)
258
259 AC3 w/ DTS passthru mode
260 ~~~~~~~~~~~~~~~~~~~~~~~~
261
262 Thanks to Hakan Lennestal, I now have a report
263
264 * ``device_setup=0x03``
265
266 - 16bits 48kHz mode with only the Do port e
267 - AC3 with DTS passthru
268 - Caution with this setup the Do port is ma
269
270 The command line used to playback the AC3/DTS
271 ::
272
273 % aplay -D hw:1,0 --channels=6 ac3_S16_LE_e
274
275 How to use the ``device_setup`` parameter
276 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
277
278 The parameter can be given:
279
280 * By manually probing the device (as root):::
281
282 # modprobe -r snd-usb-audio
283 # modprobe snd-usb-audio index=1 device_set
284
285 * Or while configuring the modules options in
286 (typically a .conf file in /etc/modprobe.d/
287
288 alias snd-card-1 snd-usb-audio
289 options snd-usb-audio index=1 device_se
290
291 CAUTION when initializing the device
292 -------------------------------------
293
294 * Correct initialization on the device requir
295 the module BEFORE the device is turned on.
296 method described above, take care to power-
297
298 * Failing to respect this will lead to a misc
299 turn off the device, unprobe the snd-usb-au
300 correct device_setup parameter and then (an
301
302 * If you've correctly initialized the device
303 to another mode (possibly with another sam
304 procedure:
305
306 - first turn off the device
307 - de-register the snd-usb-audio module (mod
308 - change the device_setup parameter by chan
309 option in ``/etc/modprobe.d/*.conf``
310 - turn on the device
311
312 * A workaround for this last issue has been a
313 be enough to ensure the 'stability' of the
314
315 Technical details for hackers
316 -----------------------------
317
318 This section is for hackers, wanting to unders
319 internals and how Alsa supports it.
320
321 Audiophile USB's ``device_setup`` structure
322 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
323
324 If you want to understand the device_setup mag
325 USB, you need some very basic understanding of
326 this is not required to use the parameter and
327
328 The device_setup is one byte long and its stru
329 ::
330
331 +---+---+---+---+---+---+---+---+
332 | b7| b6| b5| b4| b3| b2| b1| b0|
333 +---+---+---+---+---+---+---+---+
334 | 0 | 0 | 0 | Di|24B|96K|DTS|SET|
335 +---+---+---+---+---+---+---+---+
336
337 Where:
338
339 * b0 is the ``SET`` bit
340
341 - it MUST be set if device_setup is initial
342
343 * b1 is the ``DTS`` bit
344
345 - it is set only for Digital output with DT
346 - this setup is not tested
347
348 * b2 is the Rate selection flag
349
350 - When set to ``1`` the rate range is 48.1-
351 - Otherwise the sample rate range is 8-48kH
352
353 * b3 is the bit depth selection flag
354
355 - When set to ``1`` samples are 24bits long
356 - Otherwise they are 16bits long
357 - Note that b2 implies b3 as the 96kHz mode
358 samples
359
360 * b4 is the Digital input flag
361
362 - When set to ``1`` the device assumes that
363 connected
364 - You shouldn't enable Di if no source is s
365 synchronization issues)
366 - b4 is implied by b2 (since only one port
367 error can occur)
368
369 * b5 to b7 are reserved for future uses, and
370
371 - might become Ao, Do, Ai, for b7, b6, b4 r
372
373 Caution:
374
375 * there is no check on the value you will giv
376
377 - for instance choosing 0x05 (16bits 96kHz)
378 b2 implies b3. But _there_will_be_no_warn
379
380 * Hardware constraints due to the USB bus lim
381
382 - choosing b2 will prepare all interfaces f
383 only be able to use one at the same time
384
385 USB implementation details for this device
386 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
387
388 You may safely skip this section if you're not
389 hacking.
390
391 This section describes some internal aspects o
392 data I got by usb-snooping the windows and Lin
393
394 The M-Audio Audiophile USB has 7 USB Interface
395 a "USB interface":
396
397 * USB Interface nb.0
398 * USB Interface nb.1
399
400 - Audio Control function
401
402 * USB Interface nb.2
403
404 - Analog Output
405
406 * USB Interface nb.3
407
408 - Digital Output
409
410 * USB Interface nb.4
411
412 - Analog Input
413
414 * USB Interface nb.5
415
416 - Digital Input
417
418 * USB Interface nb.6
419
420 - MIDI interface compliant with the MIDIMAN
421
422 Each interface has 5 altsettings (AltSet 1,2,3
423
424 * Interface 3 (Digital Out) has an extra Alse
425 * Interface 5 (Digital In) does not have Alse
426
427 Here is a short description of the AltSettings
428
429 * AltSettings 1 corresponds to
430
431 - 24-bit depth, 48.1-96kHz sample mode
432 - Adaptive playback (Ao and Do), Synch captu
433
434 * AltSettings 2 corresponds to
435
436 - 24-bit depth, 8-48kHz sample mode
437 - Asynch capture and playback (Ao,Ai,Do,Di)
438
439 * AltSettings 3 corresponds to
440
441 - 24-bit depth, 8-48kHz sample mode
442 - Synch capture (Ai) and Adaptive playback (
443
444 * AltSettings 4 corresponds to
445
446 - 16-bit depth, 8-48kHz sample mode
447 - Asynch capture and playback (Ao,Ai,Do,Di)
448
449 * AltSettings 5 corresponds to
450
451 - 16-bit depth, 8-48kHz sample mode
452 - Synch capture (Ai) and Adaptive playback (
453
454 * AltSettings 6 corresponds to
455
456 - 16-bit depth, 8-48kHz sample mode
457 - Synch playback (Do), audio format type III
458
459 In order to ensure a correct initialization of
460 *must* *know* how the device will be used:
461
462 * if DTS is chosen, only Interface 2 with Alt
463 registered
464 * if 96KHz only AltSets nb.1 of each interfac
465 * if samples are using 24bits/48KHz then AltS
466 Digital input is connected, and only AltSet
467 is not connected
468 * if samples are using 16bits/48KHz then AltS
469 Digital input is connected, and only AltSet
470 is not connected
471
472 When device_setup is given as a parameter to t
473 parse_audio_endpoints function uses a quirk ca
474 ``audiophile_skip_setting_quirk`` in order to
475 corresponding to device_setup from being regis
476
477 Audiophile USB and Jack support
478 ===============================
479
480 This section deals with support of the Audioph
481
482 There are 2 main potential issues when using J
483
484 * support for Big-Endian devices in 24-bit mod
485 * support for 4-in / 4-out channels
486
487 Direct support in Jackd
488 -----------------------
489
490 Jack supports big endian devices only in recen
491 Andreas Steinmetz for his first big-endian pat
492 exactly when this support was released into ja
493 with jackd version 0.103.0 it's almost ok (jus
494 16bits Big-Endian devices, but since you've re
495 paragraphs, you're now using kernel >= 2.6.23
496 are now Little Endians ;-) ).
497
498 You can run jackd with the following command f
499 record with Ai:
500 ::
501
502 % jackd -R -dalsa -Phw:1,0 -r48000 -p128 -n2
503
504 Using Alsa plughw
505 -----------------
506
507 If you don't have a recent Jackd installed, yo
508 the Alsa ``plug`` converter.
509
510 For instance here is one way to run Jack with
511 capture channels from Ai:
512 ::
513
514 % jackd -R -dalsa -dplughw:1 -r48000 -p256 -
515
516 However you may see the following warning mess
517 You appear to be using the ALSA software "pl
518 using the "default" ALSA device. This is les
519 Consider using a hardware device instead rat
520
521 Getting 2 input and/or output interfaces in Ja
522 ----------------------------------------------
523
524 As you can see, starting the Jack server this
525 input (Di or Ai) and 1 stereo output (Ao or Do
526
527 This is due to the following restrictions:
528
529 * Jack can only open one capture device and on
530 * The Audiophile USB is seen as 2 (or three) A
531 (and optionally hw:1,2)
532
533 If you want to get Ai+Di and/or Ao+Do support
534 combine the Alsa devices into one logical "com
535
536 If you want to give it a try, I recommend read
537 this page: http://www.sound-man.co.uk/linuxaud
538 It is related to another device (ice1712) but
539 the Audiophile USB.
540
541 Enabling multiple Audiophile USB interfaces fo
542
543 * Making sure your Jackd version has the MMAP_
544 * (maybe) patching the alsa-lib/src/pcm/pcm_mu
545 * define a multi device (combination of hw:1,0
546 file
547 * start jackd with this device
548
549 I had no success in testing this for now, if y
550 of setup, please drop me an email.
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