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Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +02001 Guide to using M-Audio Audiophile USB with ALSA and Jack v1.3
Thibault LE MEURe3113342006-03-14 11:44:53 +01002 ========================================================
3
4 Thibault Le Meur <Thibault.LeMeur@supelec.fr>
5
6This document is a guide to using the M-Audio Audiophile USB (tm) device with
7ALSA and JACK.
8
91 - Audiophile USB Specs and correct usage
10==========================================
11This part is a reminder of important facts about the functions and limitations
12of the device.
13
14The device has 4 audio interfaces, and 2 MIDI ports:
15 * Analog Stereo Input (Ai)
Thibault LE MEUR19739fe2006-03-21 11:06:40 +010016 - This port supports 2 pairs of line-level audio inputs (1/4" TS and RCA)
17 - When the 1/4" TS (jack) connectors are connected, the RCA connectors
18 are disabled
Thibault LE MEURe3113342006-03-14 11:44:53 +010019 * Analog Stereo Output (Ao)
20 * Digital Stereo Input (Di)
21 * Digital Stereo Output (Do)
22 * Midi In (Mi)
23 * Midi Out (Mo)
24
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +020025The internal DAC/ADC has the following characteristics:
Thibault LE MEURe3113342006-03-14 11:44:53 +010026* sample depth of 16 or 24 bits
27* sample rate from 8kHz to 96kHz
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +020028* Two ports can't use different sample depths at the same time. Moreover, the
Thibault LE MEURe3113342006-03-14 11:44:53 +010029Audiophile USB documentation gives the following Warning: "Please exit any
30audio application running before switching between bit depths"
31
32Due to the USB 1.1 bandwidth limitation, a limited number of interfaces can be
33activated at the same time depending on the audio mode selected:
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +020034 * 16-bit/48kHz ==> 4 channels in/4 channels out
Thibault LE MEURe3113342006-03-14 11:44:53 +010035 - Ai+Ao+Di+Do
36 * 24-bit/48kHz ==> 4 channels in/2 channels out,
37 or 2 channels in/4 channels out
38 - Ai+Ao+Do or Ai+Di+Ao or Ai+Di+Do or Di+Ao+Do
39 * 24-bit/96kHz ==> 2 channels in, or 2 channels out (half duplex only)
40 - Ai or Ao or Di or Do
41
42Important facts about the Digital interface:
43--------------------------------------------
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +020044 * The Do port additionally supports surround-encoded AC-3 and DTS passthrough,
45though I haven't tested it under Linux
Thibault LE MEURe3113342006-03-14 11:44:53 +010046 - Note that in this setup only the Do interface can be enabled
47 * Apart from recording an audio digital stream, enabling the Di port is a way
Thibault LE MEUR19739fe2006-03-21 11:06:40 +010048to synchronize the device to an external sample clock
Thibault LE MEURe3113342006-03-14 11:44:53 +010049 - As a consequence, the Di port must be enable only if an active Digital
50source is connected
51 - Enabling Di when no digital source is connected can result in a
52synchronization error (for instance sound played at an odd sample rate)
53
54
552 - Audiophile USB support in ALSA
56==================================
57
582.1 - MIDI ports
59----------------
60The Audiophile USB MIDI ports will be automatically supported once the
61following modules have been loaded:
62 * snd-usb-audio
Thibault LE MEURe3113342006-03-14 11:44:53 +010063 * snd-seq-midi
64
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +020065No additional setting is required.
Thibault LE MEURe3113342006-03-14 11:44:53 +010066
672.2 - Audio ports
68-----------------
69
70Audio functions of the Audiophile USB device are handled by the snd-usb-audio
71module. This module can work in a default mode (without any device-specific
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +020072parameter), or in an "advanced" mode with the device-specific parameter called
Thibault LE MEURe3113342006-03-14 11:44:53 +010073"device_setup".
74
752.2.1 - Default Alsa driver mode
76
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +020077The default behavior of the snd-usb-audio driver is to parse the device
Thibault LE MEURe3113342006-03-14 11:44:53 +010078capabilities at startup and enable all functions inside the device (including
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +020079all ports at any supported sample rates and sample depths). This approach
Thibault LE MEURe3113342006-03-14 11:44:53 +010080has the advantage to let the driver easily switch from sample rates/depths
81automatically according to the need of the application claiming the device.
82
83In this case the Audiophile ports are mapped to alsa pcm devices in the
84following way (I suppose the device's index is 1):
85 * hw:1,0 is Ao in playback and Di in capture
86 * hw:1,1 is Do in playback and Ai in capture
87 * hw:1,2 is Do in AC3/DTS passthrough mode
88
89You must note as well that the device uses Big Endian byte encoding so that
90supported audio format are S16_BE for 16-bit depth modes and S24_3BE for
9124-bits depth mode. One exception is the hw:1,2 port which is Little Endian
92compliant and thus uses S16_LE.
93
94Examples:
95 * playing a S24_3BE encoded raw file to the Ao port
96 % aplay -D hw:1,0 -c2 -t raw -r48000 -fS24_3BE test.raw
97 * recording a S24_3BE encoded raw file from the Ai port
98 % arecord -D hw:1,1 -c2 -t raw -r48000 -fS24_3BE test.raw
99 * playing a S16_BE encoded raw file to the Do port
100 % aplay -D hw:1,1 -c2 -t raw -r48000 -fS16_BE test.raw
101
102If you're happy with the default Alsa driver setup and don't experience any
103issue with this mode, then you can skip the following chapter.
104
1052.2.2 - Advanced module setup
106
107Due to the hardware constraints described above, the device initialization made
108by the Alsa driver in default mode may result in a corrupted state of the
109device. For instance, a particularly annoying issue is that the sound captured
110from the Ai port sounds distorted (as if boosted with an excessive high volume
111gain).
112
113For people having this problem, the snd-usb-audio module has a new module
114parameter called "device_setup".
115
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +02001162.2.2.1 - Initializing the working mode of the Audiophile USB
Thibault LE MEURe3113342006-03-14 11:44:53 +0100117
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +0200118As far as the Audiophile USB device is concerned, this value let the user
Thibault LE MEURe3113342006-03-14 11:44:53 +0100119specify:
120 * the sample depth
121 * the sample rate
122 * whether the Di port is used or not
123
124Here is a list of supported device_setup values for this device:
125 * device_setup=0x00 (or omitted)
126 - Alsa driver default mode
127 - maintains backward compatibility with setups that do not use this
128 parameter by not introducing any change
Matt LaPlantefff92892006-10-03 22:47:42 +0200129 - results sometimes in corrupted sound as described earlier
Thibault LE MEURe3113342006-03-14 11:44:53 +0100130 * device_setup=0x01
131 - 16bits 48kHz mode with Di disabled
132 - Ai,Ao,Do can be used at the same time
133 - hw:1,0 is not available in capture mode
134 - hw:1,2 is not available
135 * device_setup=0x11
136 - 16bits 48kHz mode with Di enabled
137 - Ai,Ao,Di,Do can be used at the same time
138 - hw:1,0 is available in capture mode
139 - hw:1,2 is not available
140 * device_setup=0x09
141 - 24bits 48kHz mode with Di disabled
142 - Ai,Ao,Do can be used at the same time
143 - hw:1,0 is not available in capture mode
144 - hw:1,2 is not available
145 * device_setup=0x19
146 - 24bits 48kHz mode with Di enabled
147 - 3 ports from {Ai,Ao,Di,Do} can be used at the same time
148 - hw:1,0 is available in capture mode and an active digital source must be
149 connected to Di
150 - hw:1,2 is not available
151 * device_setup=0x0D or 0x10
152 - 24bits 96kHz mode
153 - Di is enabled by default for this mode but does not need to be connected
154 to an active source
155 - Only 1 port from {Ai,Ao,Di,Do} can be used at the same time
156 - hw:1,0 is available in captured mode
157 - hw:1,2 is not available
158 * device_setup=0x03
159 - 16bits 48kHz mode with only the Do port enabled
160 - AC3 with DTS passthru (not tested)
161 - Caution with this setup the Do port is mapped to the pcm device hw:1,0
162
1632.2.2.2 - Setting and switching configurations with the device_setup parameter
164
165The parameter can be given:
166 * By manually probing the device (as root):
167 # modprobe -r snd-usb-audio
168 # modprobe snd-usb-audio index=1 device_setup=0x09
169 * Or while configuring the modules options in your modules configuration file
170 - For Fedora distributions, edit the /etc/modprobe.conf file:
171 alias snd-card-1 snd-usb-audio
172 options snd-usb-audio index=1 device_setup=0x09
173
174IMPORTANT NOTE WHEN SWITCHING CONFIGURATION:
175-------------------------------------------
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +0200176 * You may need to _first_ initialize the module with the correct device_setup
Thibault LE MEURe3113342006-03-14 11:44:53 +0100177 parameter and _only_after_ turn on the Audiophile USB device
178 * This is especially true when switching the sample depth:
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +0200179 - first turn off the device
180 - de-register the snd-usb-audio module (modprobe -r)
181 - change the device_setup parameter by changing the device_setup
182 option in /etc/modprobe.conf
Thibault LE MEURe3113342006-03-14 11:44:53 +0100183 - turn on the device
184
Thibault LE MEUR19739fe2006-03-21 11:06:40 +01001852.2.2.3 - Audiophile USB's device_setup structure
Thibault LE MEURe3113342006-03-14 11:44:53 +0100186
187If you want to understand the device_setup magic numbers for the Audiophile
188USB, you need some very basic understanding of binary computation. However,
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +0200189this is not required to use the parameter and you may skip this section.
Thibault LE MEURe3113342006-03-14 11:44:53 +0100190
191The device_setup is one byte long and its structure is the following:
192
193 +---+---+---+---+---+---+---+---+
194 | b7| b6| b5| b4| b3| b2| b1| b0|
195 +---+---+---+---+---+---+---+---+
196 | 0 | 0 | 0 | Di|24B|96K|DTS|SET|
197 +---+---+---+---+---+---+---+---+
198
199Where:
200 * b0 is the "SET" bit
201 - it MUST be set if device_setup is initialized
202 * b1 is the "DTS" bit
203 - it is set only for Digital output with DTS/AC3
204 - this setup is not tested
205 * b2 is the Rate selection flag
206 - When set to "1" the rate range is 48.1-96kHz
207 - Otherwise the sample rate range is 8-48kHz
208 * b3 is the bit depth selection flag
209 - When set to "1" samples are 24bits long
210 - Otherwise they are 16bits long
211 - Note that b2 implies b3 as the 96kHz mode is only supported for 24 bits
212 samples
213 * b4 is the Digital input flag
214 - When set to "1" the device assumes that an active digital source is
215 connected
216 - You shouldn't enable Di if no source is seen on the port (this leads to
217 synchronization issues)
218 - b4 is implied by b2 (since only one port is enabled at a time no synch
219 error can occur)
220 * b5 to b7 are reserved for future uses, and must be set to "0"
221 - might become Ao, Do, Ai, for b7, b6, b4 respectively
222
223Caution:
224 * there is no check on the value you will give to device_setup
225 - for instance choosing 0x05 (16bits 96kHz) will fail back to 0x09 since
226 b2 implies b3. But _there_will_be_no_warning_ in /var/log/messages
227 * Hardware constraints due to the USB bus limitation aren't checked
228 - choosing b2 will prepare all interfaces for 24bits/96kHz but you'll
229 only be able to use one at the same time
230
Thibault LE MEUR19739fe2006-03-21 11:06:40 +01002312.2.3 - USB implementation details for this device
Thibault LE MEURe3113342006-03-14 11:44:53 +0100232
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +0200233You may safely skip this section if you're not interested in driver
Thibault LE MEURe3113342006-03-14 11:44:53 +0100234development.
235
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +0200236This section describes some internal aspects of the device and summarize the
237data I got by usb-snooping the windows and Linux drivers.
Thibault LE MEURe3113342006-03-14 11:44:53 +0100238
Thibault LE MEUR19739fe2006-03-21 11:06:40 +0100239The M-Audio Audiophile USB has 7 USB Interfaces:
Thibault LE MEURe3113342006-03-14 11:44:53 +0100240a "USB interface":
Thibault LE MEUR19739fe2006-03-21 11:06:40 +0100241 * USB Interface nb.0
242 * USB Interface nb.1
Thibault LE MEURe3113342006-03-14 11:44:53 +0100243 - Audio Control function
Thibault LE MEUR19739fe2006-03-21 11:06:40 +0100244 * USB Interface nb.2
Thibault LE MEURe3113342006-03-14 11:44:53 +0100245 - Analog Output
Thibault LE MEUR19739fe2006-03-21 11:06:40 +0100246 * USB Interface nb.3
Thibault LE MEURe3113342006-03-14 11:44:53 +0100247 - Digital Output
Thibault LE MEUR19739fe2006-03-21 11:06:40 +0100248 * USB Interface nb.4
Thibault LE MEURe3113342006-03-14 11:44:53 +0100249 - Analog Input
Thibault LE MEUR19739fe2006-03-21 11:06:40 +0100250 * USB Interface nb.5
Thibault LE MEURe3113342006-03-14 11:44:53 +0100251 - Digital Input
Thibault LE MEUR19739fe2006-03-21 11:06:40 +0100252 * USB Interface nb.6
Thibault LE MEURe3113342006-03-14 11:44:53 +0100253 - MIDI interface compliant with the MIDIMAN quirk
254
255Each interface has 5 altsettings (AltSet 1,2,3,4,5) except:
256 * Interface 3 (Digital Out) has an extra Alset nb.6
257 * Interface 5 (Digital In) does not have Alset nb.3 and 5
258
259Here is a short description of the AltSettings capabilities:
260 * AltSettings 1 corresponds to
261 - 24-bit depth, 48.1-96kHz sample mode
262 - Adaptive playback (Ao and Do), Synch capture (Ai), or Asynch capture (Di)
263 * AltSettings 2 corresponds to
264 - 24-bit depth, 8-48kHz sample mode
265 - Asynch capture and playback (Ao,Ai,Do,Di)
266 * AltSettings 3 corresponds to
267 - 24-bit depth, 8-48kHz sample mode
268 - Synch capture (Ai) and Adaptive playback (Ao,Do)
269 * AltSettings 4 corresponds to
270 - 16-bit depth, 8-48kHz sample mode
271 - Asynch capture and playback (Ao,Ai,Do,Di)
272 * AltSettings 5 corresponds to
273 - 16-bit depth, 8-48kHz sample mode
274 - Synch capture (Ai) and Adaptive playback (Ao,Do)
275 * AltSettings 6 corresponds to
276 - 16-bit depth, 8-48kHz sample mode
277 - Synch playback (Do), audio format type III IEC1937_AC-3
278
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +0200279In order to ensure a correct initialization of the device, the driver
Thibault LE MEURe3113342006-03-14 11:44:53 +0100280_must_know_ how the device will be used:
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +0200281 * if DTS is chosen, only Interface 2 with AltSet nb.6 must be
Thibault LE MEURe3113342006-03-14 11:44:53 +0100282 registered
283 * if 96KHz only AltSets nb.1 of each interface must be selected
284 * if samples are using 24bits/48KHz then AltSet 2 must me used if
285 Digital input is connected, and only AltSet nb.3 if Digital input
286 is not connected
287 * if samples are using 16bits/48KHz then AltSet 4 must me used if
288 Digital input is connected, and only AltSet nb.5 if Digital input
289 is not connected
290
291When device_setup is given as a parameter to the snd-usb-audio module, the
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +0200292parse_audio_endpoints function uses a quirk called
Thibault LE MEURe3113342006-03-14 11:44:53 +0100293"audiophile_skip_setting_quirk" in order to prevent AltSettings not
294corresponding to device_setup from being registered in the driver.
295
2963 - Audiophile USB and Jack support
297===================================
298
299This section deals with support of the Audiophile USB device in Jack.
300The main issue regarding this support is that the device is Big Endian
301compliant.
302
3033.1 - Using the plug alsa plugin
304--------------------------------
305
306Jack doesn't directly support big endian devices. Thus, one way to have support
307for this device with Alsa is to use the Alsa "plug" converter.
308
309For instance here is one way to run Jack with 2 playback channels on Ao and 2
310capture channels from Ai:
311 % jackd -R -dalsa -dplughw:1 -r48000 -p256 -n2 -D -Cplughw:1,1
312
313
314However you may see the following warning message:
315"You appear to be using the ALSA software "plug" layer, probably a result of
316using the "default" ALSA device. This is less efficient than it could be.
317Consider using a hardware device instead rather than using the plug layer."
318
Thibault LE MEURe3113342006-03-14 11:44:53 +01003193.2 - Patching alsa to use direct pcm device
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +0200320--------------------------------------------
Thibault LE MEURe3113342006-03-14 11:44:53 +0100321A patch for Jack by Andreas Steinmetz adds support for Big Endian devices.
322However it has not been included in the CVS tree.
323
324You can find it at the following URL:
325http://sourceforge.net/tracker/index.php?func=detail&aid=1289682&group_id=39687&
326atid=425939
327
328After having applied the patch you can run jackd with the following command
329line:
Thibault LE MEUR19739fe2006-03-21 11:06:40 +0100330 % jackd -R -dalsa -Phw:1,0 -r48000 -p128 -n2 -D -Chw:1,1
Thibault LE MEURe3113342006-03-14 11:44:53 +0100331
Charis Kouzinopoulos5732e7a2006-04-18 15:42:29 +02003323.2 - Getting 2 input and/or output interfaces in Jack
333------------------------------------------------------
334
335As you can see, starting the Jack server this way will only enable 1 stereo
336input (Di or Ai) and 1 stereo output (Ao or Do).
337
338This is due to the following restrictions:
339* Jack can only open one capture device and one playback device at a time
340* The Audiophile USB is seen as 2 (or three) Alsa devices: hw:1,0, hw:1,1
341 (and optionally hw:1,2)
342If you want to get Ai+Di and/or Ao+Do support with Jack, you would need to
343combine the Alsa devices into one logical "complex" device.
344
345If you want to give it a try, I recommend reading the information from
346this page: http://www.sound-man.co.uk/linuxaudio/ice1712multi.html
347It is related to another device (ice1712) but can be adapted to suit
348the Audiophile USB.
349
350Enabling multiple Audiophile USB interfaces for Jackd will certainly require:
351* patching Jack with the previously mentioned "Big Endian" patch
352* patching Jackd with the MMAP_COMPLEX patch (see the ice1712 page)
353* patching the alsa-lib/src/pcm/pcm_multi.c file (see the ice1712 page)
354* define a multi device (combination of hw:1,0 and hw:1,1) in your .asoundrc
355 file
356* start jackd with this device
357
358I had no success in testing this for now, but this may be due to my OS
359configuration. If you have any success with this kind of setup, please
360drop me an email.