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# SOME DESCRIPTIVE TITLE # Copyright (C) YEAR The FreeBSD Project # This file is distributed under the same license as the FreeBSD Documentation package. # FIRST AUTHOR <EMAIL@ADDRESS>, YEAR. # #, fuzzy msgid "" msgstr "" "Project-Id-Version: FreeBSD Documentation VERSION\n" "POT-Creation-Date: 2025-11-08 16:17+0000\n" "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n" "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n" "Language-Team: LANGUAGE <[email protected]>\n" "Language: \n" "MIME-Version: 1.0\n" "Content-Type: text/plain; charset=UTF-8\n" "Content-Transfer-Encoding: 8bit\n" #. type: YAML Front Matter: description #: documentation/content/en/books/arch-handbook/sound/_index.adoc:1 #, no-wrap msgid "FreeBSD Sound Subsystem" msgstr "" #. type: YAML Front Matter: title #: documentation/content/en/books/arch-handbook/sound/_index.adoc:1 #, no-wrap msgid "Chapter 15. Sound Subsystem" msgstr "" #. type: Title = #: documentation/content/en/books/arch-handbook/sound/_index.adoc:14 #, no-wrap msgid "Sound Subsystem" msgstr "" #. type: Title == #: documentation/content/en/books/arch-handbook/sound/_index.adoc:52 #, no-wrap msgid "Introduction" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:55 msgid "" "The FreeBSD sound subsystem cleanly separates generic sound handling issues " "from device-specific ones. This makes it easier to add support for new " "hardware." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:57 msgid "" "The man:pcm[4] framework is the central piece of the sound subsystem. It " "mainly implements the following elements:" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:59 msgid "" "A system call interface (read, write, ioctls) to digitized sound and mixer " "functions. The ioctl command set is compatible with the legacy _OSS_ or " "_Voxware_ interface, allowing common multimedia applications to be ported " "without modification." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:60 msgid "" "Common code for processing sound data (format conversions, virtual channels)." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:61 msgid "" "A uniform software interface to hardware-specific audio interface modules." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:62 msgid "" "Additional support for some common hardware interfaces (ac97), or shared " "hardware-specific code (ex: ISA DMA routines)." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:64 msgid "" "The support for specific sound cards is implemented by hardware-specific " "drivers, which provide channel and mixer interfaces to plug into the generic " "[.filename]#pcm# code." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:66 msgid "" "In this chapter, the term [.filename]#pcm# will refer to the central, common " "part of the sound driver, as opposed to the hardware-specific modules." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:68 msgid "" "The prospective driver writer will of course want to start from an existing " "module and use the code as the ultimate reference. But, while the sound code " "is nice and clean, it is also mostly devoid of comments. This document tries " "to give an overview of the framework interface and answer some questions " "that may arise while adapting the existing code." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:70 msgid "" "As an alternative, or in addition to starting from a working example, you " "can find a commented driver template at https://people.FreeBSD.org/~cg/" "template.c[ https://people.FreeBSD.org/~cg/template.c]" msgstr "" #. type: Title == #: documentation/content/en/books/arch-handbook/sound/_index.adoc:72 #, no-wrap msgid "Files" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:75 msgid "" "All the relevant code lives in [.filename]#/usr/src/sys/dev/sound/#, except " "for the public ioctl interface definitions, found in [.filename]#/usr/src/" "sys/sys/soundcard.h#" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:77 msgid "" "Under [.filename]#/usr/src/sys/dev/sound/#, the [.filename]#pcm/# directory " "holds the central code, while the [.filename]#pci/#, [.filename]#isa/# and " "[.filename]#usb/# directories have the drivers for PCI and ISA boards, and " "for USB audio devices." msgstr "" #. type: Title == #: documentation/content/en/books/arch-handbook/sound/_index.adoc:79 #, no-wrap msgid "Probing, Attaching, etc." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:82 msgid "" "Sound drivers probe and attach in almost the same way as any hardware driver " "module. You might want to look at the crossref:isa-driver[isa-driver,ISA] or " "crossref:pci[pci,PCI] specific sections of the handbook for more information." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:84 msgid "However, sound drivers differ in some ways:" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:86 msgid "" "They declare themselves as [.filename]#pcm# class devices, with a `struct " "snddev_info` device private structure:" msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:94 #, no-wrap msgid "" " static driver_t xxx_driver = {\n" " \"pcm\",\n" " xxx_methods,\n" " sizeof(struct snddev_info)\n" " };\n" msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:97 #, no-wrap msgid "" " DRIVER_MODULE(snd_xxxpci, pci, xxx_driver, pcm_devclass, 0, 0);\n" " MODULE_DEPEND(snd_xxxpci, snd_pcm, PCM_MINVER, PCM_PREFVER,PCM_MAXVER);\n" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:100 msgid "" "Most sound drivers need to store additional private information about their " "device. A private data structure is usually allocated in the attach routine. " "Its address is passed to [.filename]#pcm# by the calls to `pcm_register()` " "and `mixer_init()`. [.filename]#pcm# later passes back this address as a " "parameter in calls to the sound driver interfaces." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:103 msgid "" "The sound driver attach routine should declare its MIXER or AC97 interface " "to [.filename]#pcm# by calling `mixer_init()`. For a MIXER interface, this " "causes in turn a call to crossref:sound[xxxmixer-init,`xxxmixer_init()`]." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:104 msgid "" "The sound driver attach routine declares its general CHANNEL configuration " "to [.filename]#pcm# by calling `pcm_register(dev, sc, nplay, nrec)`, where " "`sc` is the address for the device data structure, used in further calls " "from [.filename]#pcm#, and `nplay` and `nrec` are the number of play and " "record channels." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:107 msgid "" "The sound driver attach routine declares each of its channel objects by " "calls to `pcm_addchan()`. This sets up the channel glue in [.filename]#pcm# " "and causes in turn a call to crossref:sound[xxxchannel-" "init,`xxxchannel_init()`]." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:108 msgid "" "The sound driver detach routine should call `pcm_unregister()` before " "releasing its resources." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:110 msgid "There are two possible methods to handle non-PnP devices:" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:112 msgid "" "Use a `device_identify()` method (example: [.filename]#sound/isa/es1888.c#). " "The `device_identify()` method probes for the hardware at known addresses " "and, if it finds a supported device, creates a new pcm device which is then " "passed to probe/attach." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:113 msgid "" "Use a custom kernel configuration with appropriate hints for pcm devices " "(example: [.filename]#sound/isa/mss.c#)." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:115 msgid "" "[.filename]#pcm# drivers should implement `device_suspend`, `device_resume` " "and `device_shutdown` routines, so that power management and module " "unloading function correctly." msgstr "" #. type: Title == #: documentation/content/en/books/arch-handbook/sound/_index.adoc:117 #, no-wrap msgid "Interfaces" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:121 msgid "" "The interface between the [.filename]#pcm# core and the sound drivers is " "defined in terms of crossref:kobj[kernel-objects,kernel objects]." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:123 msgid "" "There are two main interfaces that a sound driver will usually provide: " "_CHANNEL_ and either _MIXER_ or _AC97_." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:125 msgid "" "The _AC97_ interface is a very small hardware access (register read/write) " "interface, implemented by drivers for hardware with an AC97 codec. In this " "case, the actual MIXER interface is provided by the shared AC97 code in " "[.filename]#pcm#." msgstr "" #. type: Title === #: documentation/content/en/books/arch-handbook/sound/_index.adoc:126 #, no-wrap msgid "The CHANNEL Interface" msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:128 #, no-wrap msgid "Common Notes for Function Parameters" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:131 msgid "" "Sound drivers usually have a private data structure to describe their " "device, and one structure for each play and record data channel that it " "supports." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:133 msgid "" "For all CHANNEL interface functions, the first parameter is an opaque " "pointer." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:135 msgid "" "The second parameter is a pointer to the private channel data structure, " "except for `channel_init()` which has a pointer to the private device " "structure (and returns the channel pointer for further use by " "[.filename]#pcm#)." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:136 #, no-wrap msgid "Overview of Data Transfer Operations" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:139 msgid "" "For sound data transfers, the [.filename]#pcm# core and the sound drivers " "communicate through a shared memory area, described by a `struct snd_dbuf`." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:141 msgid "" "`struct snd_dbuf` is private to [.filename]#pcm#, and sound drivers obtain " "values of interest by calls to accessor functions (`sndbuf_getxxx()`)." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:143 msgid "" "The shared memory area has a size of `sndbuf_getsize()` and is divided into " "fixed size blocks of `sndbuf_getblksz()` bytes." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:145 msgid "" "When playing, the general transfer mechanism is as follows (reverse the idea " "for recording):" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:148 msgid "" "[.filename]#pcm# initially fills up the buffer, then calls the sound " "driver's crossref:sound[channel-trigger,`xxxchannel_trigger()`] function " "with a parameter of PCMTRIG_START." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:149 msgid "" "The sound driver then arranges to repeatedly transfer the whole memory area " "(`sndbuf_getbuf()`, `sndbuf_getsize()`) to the device, in blocks of " "`sndbuf_getblksz()` bytes. It calls back the `chn_intr()`[.filename]#pcm# " "function for each transferred block (this will typically happen at interrupt " "time)." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:150 msgid "" "`chn_intr()` arranges to copy new data to the area that was transferred to " "the device (now free), and make appropriate updates to the `snd_dbuf` " "structure." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:152 #, no-wrap msgid "channel_init" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:156 msgid "" "`xxxchannel_init()` is called to initialize each of the play or record " "channels. The calls are initiated from the sound driver attach routine. " "(See the crossref:sound[pcm-probe-and-attach,probe and attach section])." msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:168 #, no-wrap msgid "" " static void *\n" " xxxchannel_init(kobj_t obj, void *data,\n" " struct snd_dbuf *b, struct pcm_channel *c, int dir) <.>\n" " {\n" " struct xxx_info *sc = data;\n" " struct xxx_chinfo *ch;\n" " ...\n" " return ch; <.>\n" " }\n" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:171 msgid "" "`b` is the address for the channel `struct snd_dbuf`. It should be " "initialized in the function by calling `sndbuf_alloc()`. The buffer size to " "use is normally a small multiple of the 'typical' unit transfer size for " "your device.`c` is the [.filename]#pcm# channel control structure pointer. " "This is an opaque object. The function should store it in the local channel " "structure, to be used in later calls to [.filename]#pcm# (ie: " "`chn_intr(c)`).`dir` indicates the channel direction (`PCMDIR_PLAY` or " "`PCMDIR_REC`)." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:173 msgid "" "The function should return a pointer to the private area used to control " "this channel. This will be passed as a parameter to other channel interface " "calls." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:174 #, no-wrap msgid "channel_setformat" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:177 msgid "" "`xxxchannel_setformat()` should set up the hardware for the specified " "channel for the specified sound format." msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:187 #, no-wrap msgid "" " static int\n" " xxxchannel_setformat(kobj_t obj, void *data, u_int32_t format) <.>\n" " {\n" " struct xxx_chinfo *ch = data;\n" " ...\n" " return 0;\n" " }\n" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:190 msgid "" "`format` is specified as an `AFMT_XXX value` ([.filename]#soundcard.h#)." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:191 #, no-wrap msgid "channel_setspeed" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:194 msgid "" "`xxxchannel_setspeed()` sets up the channel hardware for the specified " "sampling speed, and returns the possibly adjusted speed." msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:204 #, no-wrap msgid "" " static int\n" " xxxchannel_setspeed(kobj_t obj, void *data, u_int32_t speed)\n" " {\n" " struct xxx_chinfo *ch = data;\n" " ...\n" " return speed;\n" " }\n" msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:206 #, no-wrap msgid "channel_setblocksize" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:209 msgid "" "`xxxchannel_setblocksize()` sets the block size, which is the size of unit " "transactions between [.filename]#pcm# and the sound driver, and between the " "sound driver and the device. Typically, this would be the number of bytes " "transferred before an interrupt occurs. During a transfer, the sound driver " "should call [.filename]#pcm#'s `chn_intr()` every time this size has been " "transferred." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:211 msgid "" "Most sound drivers only take note of the block size here, to be used when an " "actual transfer will be started." msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:221 #, no-wrap msgid "" " static int\n" " xxxchannel_setblocksize(kobj_t obj, void *data, u_int32_t blocksize)\n" " {\n" " struct xxx_chinfo *ch = data;\n" " ...\n" " return blocksize; <.>\n" " }\n" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:224 msgid "" "The function returns the possibly adjusted block size. In case the block " "size is indeed changed, `sndbuf_resize()` should be called to adjust the " "buffer." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:226 #, no-wrap msgid "channel_trigger" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:229 msgid "" "`xxxchannel_trigger()` is called by [.filename]#pcm# to control data " "transfer operations in the driver." msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:239 #, no-wrap msgid "" " static int\n" " xxxchannel_trigger(kobj_t obj, void *data, int go) <.>\n" " {\n" " struct xxx_chinfo *ch = data;\n" " ...\n" " return 0;\n" " }\n" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:242 msgid "`go` defines the action for the current call. The possible values are:" msgstr "" #. type: delimited block = 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:246 msgid "" "If the driver uses ISA DMA, `sndbuf_isadma()` should be called before " "performing actions on the device, and will take care of the DMA chip side of " "things." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:248 #, no-wrap msgid "channel_getptr" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:251 msgid "" "`xxxchannel_getptr()` returns the current offset in the transfer buffer. " "This will typically be called by `chn_intr()`, and this is how " "[.filename]#pcm# knows where it can transfer new data." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:252 #, no-wrap msgid "channel_free" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:255 msgid "" "`xxxchannel_free()` is called to free up channel resources, for example when " "the driver is unloaded, and should be implemented if the channel data " "structures are dynamically allocated or if `sndbuf_alloc()` was not used for " "buffer allocation." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:256 #, no-wrap msgid "channel_getcaps" msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:265 #, no-wrap msgid "" " struct pcmchan_caps *\n" " xxxchannel_getcaps(kobj_t obj, void *data)\n" " {\n" " return &xxx_caps; <.>\n" " }\n" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:268 msgid "" "The routine returns a pointer to a (usually statically-defined) " "`pcmchan_caps` structure (defined in [.filename]#sound/pcm/channel.h#. The " "structure holds the minimum and maximum sampling frequencies, and the " "accepted sound formats. Look at any sound driver for an example." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:269 #, no-wrap msgid "More Functions" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:272 msgid "" "`channel_reset()`, `channel_resetdone()`, and `channel_notify()` are for " "special purposes and should not be implemented in a driver without " "discussing it on the {freebsd-multimedia}." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:274 msgid "`channel_setdir()` is deprecated." msgstr "" #. type: Title === #: documentation/content/en/books/arch-handbook/sound/_index.adoc:275 #, no-wrap msgid "The MIXER Interface" msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:278 #, no-wrap msgid "mixer_init" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:281 msgid "" "`xxxmixer_init()` initializes the hardware and tells [.filename]#pcm# what " "mixer devices are available for playing and recording" msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:289 #, no-wrap msgid "" " static int\n" " xxxmixer_init(struct snd_mixer *m)\n" " {\n" " struct xxx_info *sc = mix_getdevinfo(m);\n" " u_int32_t v;\n" msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:291 #, no-wrap msgid " [Initialize hardware]\n" msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:296 #, no-wrap msgid "" " [Set appropriate bits in v for play mixers] <.>\n" " mix_setdevs(m, v);\n" " [Set appropriate bits in v for record mixers]\n" " mix_setrecdevs(m, v)\n" msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:299 #, no-wrap msgid "" " return 0;\n" " }\n" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:302 msgid "" "Set bits in an integer value and call `mix_setdevs()` and `mix_setrecdevs()` " "to tell [.filename]#pcm# what devices exist." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:304 msgid "" "Mixer bits definitions can be found in [.filename]#soundcard.h# " "(`SOUND_MASK_XXX` values and `SOUND_MIXER_XXX` bit shifts)." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:305 #, no-wrap msgid "mixer_set" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:308 msgid "`xxxmixer_set()` sets the volume level for one mixer device." msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:319 #, no-wrap msgid "" " static int\n" " xxxmixer_set(struct snd_mixer *m, unsigned dev,\n" " unsigned left, unsigned right) <.>\n" " {\n" " struct sc_info *sc = mix_getdevinfo(m);\n" " [set volume level]\n" " return left | (right << 8); <.>\n" " }\n" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:322 msgid "" "The device is specified as a `SOUND_MIXER_XXX` value. The volume values are " "specified in range [0-100]. A value of zero should mute the device." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:323 msgid "" "As the hardware levels probably will not match the input scale, and some " "rounding will occur, the routine returns the actual level values (in range " "0-100) as shown." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:324 #, no-wrap msgid "mixer_setrecsrc" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:327 msgid "`xxxmixer_setrecsrc()` sets the recording source device." msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:334 #, no-wrap msgid "" " static int\n" " xxxmixer_setrecsrc(struct snd_mixer *m, u_int32_t src) <.>\n" " {\n" " struct xxx_info *sc = mix_getdevinfo(m);\n" msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:336 #, no-wrap msgid " [look for non zero bit(s) in src, set up hardware]\n" msgstr "" #. type: delimited block . 4 #: documentation/content/en/books/arch-handbook/sound/_index.adoc:340 #, no-wrap msgid "" " [update src to reflect actual action]\n" " return src; <.>\n" " }\n" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:343 msgid "The desired recording devices are specified as a bit field" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:344 msgid "" "The actual devices set for recording are returned. Some drivers can only set " "one device for recording. The function should return -1 if an error occurs." msgstr "" #. type: Title ==== #: documentation/content/en/books/arch-handbook/sound/_index.adoc:345 #, no-wrap msgid "mixer_uninit, mixer_reinit" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:348 msgid "" "`xxxmixer_uninit()` should ensure that all sound is muted and if possible " "mixer hardware should be powered down." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:350 msgid "" "`xxxmixer_reinit()` should ensure that the mixer hardware is powered up and " "any settings not controlled by `mixer_set()` or `mixer_setrecsrc()` are " "restored." msgstr "" #. type: Title === #: documentation/content/en/books/arch-handbook/sound/_index.adoc:351 #, no-wrap msgid "The AC97 Interface" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:354 msgid "" "The _AC97_ interface is implemented by drivers with an AC97 codec. It only " "has three methods:" msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:356 msgid "`xxxac97_init()` returns the number of ac97 codecs found." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:357 msgid "`ac97_read()` and `ac97_write()` read or write a specified register." msgstr "" #. type: Plain text #: documentation/content/en/books/arch-handbook/sound/_index.adoc:358 msgid "" "The _AC97_ interface is used by the AC97 code in [.filename]#pcm# to perform " "higher level operations. Look at [.filename]#sound/pci/maestro3.c# or many " "others under [.filename]#sound/pci/# for an example." msgstr ""