--- name: "oss_envy24" section: "7" platform: "linux" package: "oss4-base" version: "4.2-build2010-2" release: "Debian 8 (Jessie)" platforms: ["linux"] url: "https://new.carta.tech/oss_envy24" --- # oss\_envy24(7) ICE Envy24 audio device driver. ## NAME **oss\_envy24** - ICE Envy24 audio device driver. ## DESCRIPTION **Open Sound System driver for Envy24 based audio cards such as the** **M-Audio Delta Series, Terratec EWS88 Series, Hoontech DSP24.** ``` ENVY24 device characteristics: ``` - • **8/16 bit playback/record** - • **mono/stereo/4ch/5.1ch/7.1ch playback** - • **mono/sterero recording** - • **8KHz to 192Khz sample rate.** ``` ENVY24 AUDIO DEVICES Audio devices: 0: M Audio Delta 1010 out1/2 1: M Audio Delta 1010 out3/4 2: M Audio Delta 1010 out5/6 3: M Audio Delta 1010 out7/8 4: M Audio Delta 1010 S/PDIF out 5: M Audio Delta 1010 in1/2 6: M Audio Delta 1010 in3/4 7: M Audio Delta 1010 in5/6 8: M Audio Delta 1010 in7/8 9: M Audio Delta 1010 S/PDIF in 10: M Audio Delta 1010 input from mon. mixer 11: M Audio Delta 1010 (all outputs) 12: M Audio Delta 1010 (all inputs) Synth devices: Midi devices: 0: M Audio Delta 1010 Timers: 0: System clock Mixers: 0: M Audio Delta 1010 ``` **The actual /dev/dsp# numbers may be different on your system. Check the right** **ones by looking at the output procuced by "ossinfo -a" command. With the** **above configuration you can use /dev/dsp0 to /dev/dsp4 for playback of stereo** **streams. If you play mono files the signal will be output only from the left** **channel. /dev/dsp0 to /dev/dsp3 are connected to the analog outputs while** **/dev/dsp4 is the S/PDIF output.** **The /dev/dsp5 to /dev/dsp10 device files can be used for recording. /dev/dsp5** **to /dev/dsp8 are the analog inputs. /dev/dsp11 and /dev/dsp12 are raw** **input/output device files. They will be described in detail in the "Raw I/O** **devices" section below.** **It's also possible to make OSS to create individual device files for every** **channel this creates twice as many device files than the default setting. To** **do this just append envy24\_skipdevs=1 to the oss\_envy24.conf file. This is useful** **only if you are working on mono rather than stereo signals. However please** **note that setting envy24\_skipdevs=1 does \_NOT\_ lock the device files to one** **channel mode, the application can still set them to stereo or multi channel** **mode if it likes.** **It is possible to set all device files to mono only mode by setting** **envy24\_skipdevs=1 and envy24\_force\_mono=1. However this mode disables stereo** **and multi channel usage for all devices so in general it should not be used.** **By default the driver will create output devices before the input ones. By** **setting envy24\_swapdevs=1 in oss\_envy24.conf you can ask OSS to create the device** **files in opposite order i.e. input device files before the output ones. This** **may be useful when using RealProducer.** **As a workaround to a bug in RealProducer you also need to create some dummy** **mixer devices by defining envy24\_realencoder\_hack=1 in oss\_envy24.conf. Without** **these extra mixer devices RealProducer will not be able to access other than** **the first input device.** ### DEVICE MANAGEMENT **By default OSS creates a large number of device files for each envy24 card.** **This may be a problem when multiple cards need to be used in the same system.** **Adding the envy24\_devmask option to oss\_envy24.conf should help** **in most cases because it removes the devices that are actually not needed in** **the system.** **The envy24\_devmask number is the SUM of the following values:** ``` 1: Create primary (analog/ADAT/TDIF) outputs. 2: Create primary (analog/ADAT/TDIF) inputs. 4: Create S/PDIF outputs. 8: Create S/PDIF inputs. 16: Create monitor input device. 32: Create the raw input and output devices. ``` **For example envy24\_devmask=12 (4+8) creates only the S/PDIF devices.** **To enable all possible (current or future) device files set envy24\_devmask** **to 65535 (default).** **If possible make your application to open the right device file** **(/dev/dsp0 to /dev/dsp10) explicitly. It's also possible to use the** **default devicefile (/dev/dsp) since OSS now supports automatic device** **allocation (it opens the first available input or output devicefile** **depending on the open mode).** **The channel allocation mechanism between device files is very flexible.** **Even there is a device file for every stereo pair (or a mono channel)** **it's possible to use any of the device file to access multiple channels.** **For example an application can open /dev/dsp0 and set the number of** **channels to 10. In this way the application can play all 10 channels** **(or any number between 1 and 10) simultaneously (the samples will be** **interleaved).** **There is simple automatic syncstart feature when using multiple** **applications at the same time. Playback will not start before all** **currently open devices files have started the playback operation.** **The same mechanism works for recording (recording and playback** **operations are fully independent).** **The Envy24 driver supports 8, 16 and 24/32 bit sample formats.** ### SAMPLING RATE **Envy24 based cards are multi channel devices and all the channels share the** **same sampling rate. For this reason the sampling rate is normally locked to the** **value selected using ossmix. However OSS supports some other methods for** **changing the sampling rate. There are four ways to change the sampling rate.** ``` BASIC METHOD: ``` **Since all input and output channels of Envy24 work at the same sampling rate** **it's not possible for the applications to select the rate themselves. Instead** **the sampling rate is always locked to the currently selected rate. This rate** **selection can be changed using the ossmix program shipped with OSS.** **For example:** ``` ossmix envy24.rate 48000 ``` **sets the sampling rate to 48000 Hz (default). The possible alternatives are** - • **8000** - • **9600** - • **11025** - • **12000** - • **16000** - • **22050** - • **24000** - • **32000** - • **44100** - • **48000** - • **88200** - • **96000** **When using S/PDIF inputs/outputs only the sampling rates 32000, 44100, 48000, 88200 or 96000 should be used.** ### EXTERNAL SYNC **It's possible to lock the sampling rate to the S/PDIF or world clock inputs** **by setting the envy24.sync setting in ossmix to SPDIF or WCLOCK. However** **the envy24.rate setting should be set manually to match the rate being used** **(there is no autodetection for that).** ### NONLOCKED METHOD **It's also possible to turn the envy24.ratelock setting to OFF using ossmix.** **After that the first application that opens the device can change the sampling** **rate. However great care should be taken that this application gets the** **recording/playback process fully started before any of the other** **applications open their devices. Otherwise all devices will be locked to 8Khz.** **Also keep in mind that subsequent applications will be forced to use the** **sampling rate set by the first one.** ### SOFTWARE SRC **OSS contains a very high quality software based sample rate converter.** **It can be enabled by setting envy24.src to ON using ossmix.** **After that OSS can do on-fly sample rate conversions between the actual** **"hardware" sampling rate and the sampling rates used by the applications. In** **this way every application may use different sampling rate. However there are** **some drawbacks in this method:** - • **The hardware rate needs to be 44100, 48000 or 96000 Hz.** - • **The software SRC algorithm consumes some CPU time (1% to 20% per audio** **channel depending on the CPU speed and sampling rates). For this reason this** **method may be useless in multi channel use with anything else but the fastest** **high end CPUs.** - • **Only mono and stereo (1 or 2 channel) streams are supported.** - • **The SRC algorithm does cause minor artifacts to the sound (SNR is around 60 dB).** ### RAW IO DEVICES **These device files provide an alternative way to access Envy24 based devices.** **With these devices it's possible to bypass the dual buffering required by the** **"normal" input-output device files described above. This means that also the** **mmap() feature is available and that the latencies caused by dual buffering** **are gone. So these device files work much like "ordinary" soundcards. However** **due to multi channel professional nature of the Envy24 chip there are some very** **fundamental differences. This means that these device files can only be used** **with applications that are aware of them.** **The differences from normal audio device files are:** - 1\. **The sample format will always be 32 bit msb aligned (AFMT\_S32\_LE). Trying to** **use any other sample format will cause unexpected results.** - 2\. **Number of channels is fixed and cannot be changed. The output device has** **always 10 channels (0 to 7 are analog outputs and 8 to 9 are the digital** **outputs). This assignment will be used even with cards that don't support** **digital (or analog) outputs at all. If the actual hardware being used has** **less channels the unused ones will be discarded (however they will be fed to** **the on board monitor mixer).** **The input device is fixed to 12 channels. Channels 0 to 7 are analog inputs.** **Channels 8 to 9 are digital inputs. Channels 10 and 11 are for the result** **signal from the on board monitor mixer.** ### DIGITAL MONITOR MIXER **All Envy24 based cards have a built in monitor mixer. It can be used to mix** **allinput and output signals together. The result can be recorded from the** **"input from mon mixer" device (device 10 in the /dev/sndstat example above).** **The monitor mix signal can also be routed to any of the outputs (including** **S/PDIF and the "consumer" AC97 output of Terratec EWS88MT/D and any other card** **that support s it).** **The settings in the gain.\* group of ossmix are used to change the levels of all** **inputs and outputs in the digital monitor mixer. The possible values are** **between 0 (minimum) and 144 (maximum).** **OSS permits using all 10 possible output channels of the monitor mixer even** **with cards that have less physical outputs. These "virtual" outputs are only** **sent to the monitor mixer and their signal is only present in the monitor mixer** **output. To enable these "virtual" channels set the envy24\_virtualout parameter** **to 1 in oss\_envy24.conf. This option has no effect with Delta1010, EWS88MT and** **other cards that have 10 "real" outputs.** ### SYNC SOURCE **On cards with S/PDIF and/or World Clock inputs it's possible to select the** **sync source using** ``` ossmix envy24.sync ``` **The possible choices are:** - • **INTERNAL: Use the internal sampling rate as defined by envy24.rate** - • **SPDIF: Use the S/PDIF input as the clock source. The envy24.rate setting** **must be set manually to match the actual input sampling rate.** - • **WCLOCK: Like SPDIF but uses the world clock input signal (Delta 1010 only).** ### OUTPUT ROUTINGS **Output routing of output ports can be changed by changing the route.\* settings** **using ossmix. The possible choices are:** - • **DMA: Playback from the associated /dev/dsp# device.** - • **MONITOR: Output of the digital mixer (only out1/2 and S/PDIF).** - • **IN1/2 to IN9/10 or IN1 to IN10: Loopback from the analog inputs** - • **SPDIFL or SPDIFR or SPDIF: Loopback from the S/PDIF input.** ### PEAK METERS **Envy24 based cards have peak meters for the input and output ports of the** **digital monitor mixer. ossmix can show these values under the peak.\* group** **(these settings are read only). The values are between 0 (minimum) and 255** **(maximum). At this moment the only applications that supports these peak meters** **are ossmix and ossxmix.** ### AUDIO LATENCY **IDE disk and CD-ROM drives may cause some interrupt latency problems which** **may cause dropouts in recording/playback with Envy24 based cards. For this** **reason ensure that DMA is turned on for the disk drive.** **Another method to solve the dropout problems is making the fragment size used** **by the driver longer. This can be done by adding envy24\_nfrags=N to the** **oss\_envy24.conf file. By default N is 16. Values 2, 4 or 8 make the fragments** **longer which should cure the dropout problems. However this may cause** **latency problems with some applications. Values 32 and 64 decrease the** **latencies but may cause dropouts with IDE.** ## OPTIONS - • **envy24\_skipdevs: It's also possible to make OSS to create individual device** **files for every channel. This creates twice as many device files than the** - **default setting.** **Values: 1, 0 Default: 0** - • **envy24\_swapdevs: By default the driver will create output devices before the** **input ones. You can force the input devices to be configured before output** **devices.** **Values: 1, 0 Default: 0** - • **envy24\_realencoder\_hack: RealProducer wants to see a mixer device in** **/dev/mixer. This option allows you to define a dummy /dev/mixer mixer device.** **Envy24 Mixer device doesn't provide any consumer level soundcard compatibility** **so this dummy mixer fools RealProducer into thinking it's running on a consumer** **soundcard like SB Pro or SBLive.** **Values: 1, 0 Default: 0** - • **envy24\_gain\_sliders: With some devices it's possible to change the gain** **controllers to be continuous sliders instead of just enumerated ones.** **Values: 1, 0 Default: 0** - • **envy24\_nfrags: To solve the dropout problems make the fragment size used by** **the driver longer. By default is 16. Values 2, 4 or 8 make the fragments longer** **which should cure the dropout problems. However this may cause latency problems** **with some applications. Values 32 and 64 decrease the latencies but may cause** **dropouts with IDE drives.** **Values: 2-64 Default: 16** - • **envy24\_virtualout: OSS permits using all 10 possible output channels of the** **monitor mixer even with cards that have less physical outputs. These "virtual"** **outputs are only sent to the monitor mixer and their signal is only present in** **the monitor mixer output. This has no effect for Delta1010 or Terratec EWS88MT.** **Values: 1, 0 Default: 0** - • **envy24\_force\_mono: It is possible to set all device files to mono only mode** **by setting envy24\_skipdevs=1 and envy24\_force\_mono=1. However this mode** **disables stereo and multi channel usage for all devices so in general it should** **not be used.** **Values: 1, 0 Default: 0** ## FILES **/etc/oss4/conf/oss\_envy24.conf Device configuration file** ## AUTHOR **4Front Technologies**