Provided by: oss4-base_4.2-build2005-2ubuntu1_amd64 bug

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

                                         05 February 2012                           oss_envy24(7)