Provided by: oss4-base_4.2-build2004-1ubuntu2_i386
oss_envy24 - ICE Envy24 audio device driver.
Open Sound System driver for Envy24 based audio cards such as the M-
Audio Delta Series, Terratec EWS88 Series, Hoontech DSP24.
ENVY24 device characteristics:
o 8/16 bit playback/record
o mono/stereo/4ch/5.1ch/7.1ch playback
o mono/sterero recording
o 8KHz to 192Khz sample rate.
ENVY24 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)
0: M Audio Delta 1010
0: System clock
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 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.
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.
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.
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.
ossmix envy24.rate 48000
sets the sampling rate to 48000 Hz (default). The possible alternatives
When using S/PDIF inputs/outputs only the sampling rates 32000, 44100,
48000, 88200 or 96000 should be used.
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).
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.
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:
o The hardware rate needs to be 44100, 48000 or 96000 Hz.
o 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.
o Only mono and stereo (1 or 2 channel) streams are supported.
o 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
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
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.
On cards with S/PDIF and/or World Clock inputs it's possible to select
the sync source using
The possible choices are:
o INTERNAL: Use the internal sampling rate as defined by envy24.rate
o SPDIF: Use the S/PDIF input as the clock source. The envy24.rate
setting must be set manually to match the actual input sampling
o WCLOCK: Like SPDIF but uses the world clock input signal (Delta 1010
Output routing of output ports can be changed by changing the route.*
settings using ossmix. The possible choices are:
o DMA: Playback from the associated /dev/dsp# device.
o MONITOR: Output of the digital mixer (only out1/2 and S/PDIF).
o IN1/2 to IN9/10 or IN1 to IN10: Loopback from the analog inputs
o SPDIFL or SPDIFR or SPDIF: Loopback from the S/PDIF input.
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.
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.
o 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
Values: 1, 0 Default: 0
o 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
o 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
o 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
o 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
o 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
o 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:
/etc/oss4/conf/oss_envy24.conf Device configuration file
27 September 2011 oss_envy24(7)