1 ==============================================
2 Brief Notes on C-Media 8338/8738/8768/8770 Dri
3 ==============================================
4
5 Takashi Iwai <tiwai@suse.de>
6
7
8 Front/Rear Multi-channel Playback
9 ---------------------------------
10
11 CM8x38 chip can use ADC as the second DAC so t
12 channels can be used for front/rear playbacks.
13 DACs, both streams are handled independently u
14 channel playbacks in the section below.
15
16 As default, ALSA driver assigns the first PCM
17 card#0) for front and 4/6ch playbacks, while t
18 (hw:0,1) is assigned to the second DAC for rea
19
20 There are slight differences between the two D
21
22 - The first DAC supports U8 and S16LE formats,
23 supports only S16LE.
24 - The second DAC supports only two channel ste
25
26 Please note that the CM8x38 DAC doesn't suppor
27 rate but only fixed rates: 5512, 8000, 11025,
28 44100 and 48000 Hz.
29
30 The rear output can be heard only when "Four C
31 disabled. Otherwise no signal will be routed
32 As default it's turned on.
33
34 .. WARNING::
35 When "Four Channel Mode" switch is off, the
36 will be FULL VOLUME regardless of Master and
37 This might damage your audio equipment. Ple
38 before your turn off this switch.
39
40
41 .. [#]
42 Well.. I once got the output with correct vo
43 front one) and was so excited. It was even
44 on and "double DAC" mode. Actually I could
45 from front and rear speakers! But.. after r
46 It's a very pity that I didn't save the regi
47 time.. Maybe there is an unknown register t
48
49 If your card has an extra output jack for the
50 playback should be routed there as default. I
51 control switch in the driver "Line-In As Rear"
52 via alsamixer or somewhat else. When this swi
53 is used as rear output.
54
55 There are two more controls regarding to the r
56 The "Exchange DAC" switch is used to exchange
57 routes, i.e. the 2nd DAC is output from front
58
59
60 4/6 Multi-Channel Playback
61 --------------------------
62
63 The recent CM8738 chips support for the 4/6 mu
64 function. This is useful especially for AC3 d
65
66 When the multi-channel is supported, the drive
67 "-MC" such like "CMI8738-MC6". You can check
68 /proc/asound/cards.
69
70 When the 4/6-ch output is enabled, the second
71 4) channels. While the dual DAC supports two
72 formats, the 4/6-ch playback supports only the
73 channels. Since the multi-channel playback mo
74 cannot operate with full-duplex.
75
76 The 4.0 and 5.1 modes are defined as the pcm "
77 in alsa-lib. For example, you can play a WAV
78 ::
79
80 % aplay -Dsurround51 sixchannels.wav
81
82 For programming the 4/6 channel playback, you
83 channels as you like and set the format S16LE.
84 with 4 channels,
85 ::
86
87 snd_pcm_hw_params_set_access(pcm, hw,
88 // or mmap if you like
89 snd_pcm_hw_params_set_format(pcm, hw,
90 snd_pcm_hw_params_set_channels(pcm, hw
91
92 and use the interleaved 4 channel data.
93
94 There are some control switches affecting to t
95
96 Line-In Mode
97 an enum control to change the behavior
98 jack. Either "Line-In", "Rear Output"
99 be selected. The last item is availab
100 or newer.
101 When "Rear Output" is chosen, the surr
102 are output to line-in jack.
103 Mic-In Mode
104 an enum control to change the behavior
105 jack. Either "Mic-In" or "Center/LFE
106 selected.
107 When "Center/LFE Output" is chosen, th
108 channels (channels 5 and 6) are output
109
110 Digital I/O
111 -----------
112
113 The CM8x38 provides the excellent SPDIF capabi
114 price (yes, that's the reason I bought the car
115
116 The SPDIF playback and capture are done via th
117 (hw:0,2). Usually this is assigned to the PCM
118 The available rates are 44100 and 48000 Hz.
119 For playback with aplay, you can run like belo
120 ::
121
122 % aplay -Dhw:0,2 foo.wav
123
124 or
125
126 ::
127
128 % aplay -Dspdif foo.wav
129
130 24bit format is also supported experimentally.
131
132 The playback and capture over SPDIF use normal
133 respectively, so you cannot playback both anal
134 simultaneously.
135
136 To enable SPDIF output, you need to turn on "I
137 control via mixer or alsactl ("IEC958" is the
138 so-called S/PDIF). Then you'll see the red li
139 you know that's working obviously :)
140 The SPDIF input is always enabled, so you can
141 from line-out with "IEC958 In Monitor" switch
142 below).
143
144 You can play via SPDIF even with the first dev
145 but SPDIF is enabled only when the proper form
146 (441100 or 48000) and channels (2) are used.
147 off. (Also don't forget to turn on "IEC958 Ou
148
149
150 Additionally there are relevant control switch
151
152 IEC958 Mix Analog
153 Mix analog PCM playback and FM-OPL/3 s
154 output through SPDIF. This switch app
155 models (CM8738 033 and 037).
156
157 Note: without this control you can out
158 This is "mixing" of streams, so e.g. i
159 (see the next section).
160
161 IEC958 In Select
162 Select SPDIF input, the internal CD-in
163 and the external input (true).
164
165 IEC958 Loop
166 SPDIF input data is loop back into SPD
167 output (aka bypass)
168
169 IEC958 Copyright
170 Set the copyright bit.
171
172 IEC958 5V
173 Select 0.5V (coax) or 5V (optical) int
174 On some cards this doesn't work and yo
175 configuration with hardware dip-switch
176
177 IEC958 In Monitor
178 SPDIF input is routed to DAC.
179
180 IEC958 In Phase Inverse
181 Set SPDIF input format as inverse.
182 [FIXME: this doesn't work on all chips
183
184 IEC958 In Valid
185 Set input validity flag detection.
186
187 Note: When "PCM Playback Switch" is on, you'll
188 stream through analog line-out.
189
190
191 The AC3 (RAW DIGITAL) OUTPUT
192 ----------------------------
193
194 The driver supports raw digital (typically AC3
195 can be toggled via IEC958 playback control, bu
196 access it via alsa-lib. See alsa-lib document
197
198 On the raw digital mode, the "PCM Playback Swi
199 turned off so that non-audio data is heard fro
200 Similarly the following switches are off: "IEC
201 "IEC958 Loop". The switches are resumed after
202 device automatically to the previous state.
203
204 On the model 033, AC3 is implemented by the so
205 the alsa-lib. If you need to bypass the softw
206 subframes, pass the "soft_ac3=0" module option
207 on the newer models.
208
209
210 ANALOG MIXER INTERFACE
211 ----------------------
212
213 The mixer interface on CM8x38 is similar to SB
214 There are Master, PCM, Synth, CD, Line, Mic an
215 volumes. Synth, CD, Line and Mic have playbac
216 too, as well as SB16.
217
218 In addition to the standard SB mixer, CM8x38 p
219 - PCM playback switch
220 - PCM capture switch (to capture the data sent
221 - Mic Boost switch
222 - Mic capture volume
223 - Aux playback volume/switch and capture switc
224 - 3D control switch
225
226
227 MIDI CONTROLLER
228 ---------------
229
230 With CMI8338 chips, the MPU401-UART interface
231 You need to set the module option "mpu_port" t
232 to enable MIDI support. Valid I/O ports are 0
233 0x330. Choose a value that doesn't conflict w
234
235 With CMI8738 and newer chips, the MIDI interfa
236 and the driver automatically chooses a port ad
237
238 There is *no* hardware wavetable function on t
239 OPL3 synth below).
240 What's said as MIDI synth on Windows is a soft
241 emulation. On Linux use TiMidity or other sof
242 playing MIDI music.
243
244
245 FM OPL/3 Synth
246 --------------
247
248 The FM OPL/3 is also enabled as default only f
249 Set "fm_port" module option for more cards.
250
251 The output quality of FM OPL/3 is, however, ve
252 I don't know why..
253
254 CMI8768 and newer chips do not have the FM syn
255
256
257 Joystick and Modem
258 ------------------
259
260 The legacy joystick is supported. To enable t
261 joystick_port=1 module option. The value 1 me
262 If the auto-detection fails, try to pass the e
263
264 The modem is enabled dynamically via a card co
265
266
267 Debugging Information
268 ---------------------
269
270 The registers are shown in /proc/asound/cardX/
271 problem (especially unexpected behavior of mix
272 output of this proc file together with the bug
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