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Open Sound System OSS 4.x User's Guide

oss_madi - RME HDSP MADI and AES32 audio driver

Open Sound System driver for RME HDSP MADI and AES32 audio interfaces.

This driver has been developed for RME HDSP MADI but it also supports HDSP AES32. The driver has been tested under Linux and Solaris under x86 and Sparc.

The internal engine of the card supports 64 playback channels and 64 recording channels. Only the first channels are connected to the actual input and output ports of the card.

The mixer section of the card has recording level settings for all inputs. There is also an output mixer. Each output channel has mixer sliders for corresponding input channel and corresponding audio playback channel.

There is a full 64x(64+64) mixing matrix supported by the hardware. For the time being this mixer matrix cannot be accessed directly by the applications. However support for the SNDCTL_MIX_MATRIX_WRITE and SNDCTL_MIX_MATRIX_READ ioctl calls can be added in the future.

DEVICE FILES

By default the driver will create input and output device files for each 32 stereo pairs. This can be changed by editing the settings in oss_madi.conf (see below).

The application can set the devices to use 1, 2, 4, 8, 16, 32 or 64 channels. The device file being used selects the first channel slot within the available channels. For example pcm0 and pcmin0 sill select channel 0. Equally well pcm1 and pcmin1 will select channel slot 2 (assuming that madi_devsize option is set to 2). The first device (pcm0 and pcmin0) can be set to use up to 64 channels. The last devices (pcm31 and pcmin31) only support 1 or 2 channel mode. The other device files support channel configurations where the last channel doesn't exceed the number of total channels (madi_maxchannels). Also the driver will not let two device files to share any of the channels with some other open device file.

This channel allocation mechanism gives maximum flexibility to the user. It is possible to use some output channels by multi channel application while the others are available for other applications. This works as long the channel allocations by different applications don't overlap.

OPTIONS

• madi_maxchannels Number of channels supported by the driver. The default is 64 which is also the maximum. This parameter can
  be set to a lower value if full 64 channels are not
  required. With less channels the mixer/control panel
  interface will require less space on screen.
  
• madi_devsize By default this parameter is set to 2 which means that a device file will be created for each stereo channel
  pair. Possible values are 1, 2, 4, 8, 16, 32 or 64.
  

LIMITATIONS

• The current driver doesn't support all control panel features of the card. For example sampling rate is fixed to 48 kHz. More features will be added on contract.

• Use of mmap() is and will not be supported.
• Virtual mixer is not supported (yet).

FILES

oss_madi.conf Device configuration file.

AUTHOR

4Front Technologies