NAME

Audio::OSS - pure-perl interface to OSS (open sound system) audio devices

SYNOPSIS

use Audio::OSS qw(:funcs :formats);

my $dsp = IO::Handle->new("</dev/dsp") or die "open failed: $!";
dsp_reset($dsp) or die "reset failed: $!";

my $mask = get_supported_formats($dsp);
if ($mask & AFMT_S16_LE) {
  set_fmt($dsp, AFMT_S16_LE) or die set format failed: $!";
}
my $current_format = set_fmt($dsp, AFMT_QUERY);

my $sps_actual = set_sps($dsp, 16000);

set_fragment($dsp, $fragshift, $nfrags);
my ($frags_avail, $frags_total, $fragsize, $bytes_avail)
    = get_outbuf_info($dsp);
my ($bytes, $blocks, $dma_ptr) = get_outbuf_ptr($dsp);

DESCRIPTION

Audio::OSS is a pure Perl interface to the Open Sound System, as used on Linux, FreeBSD, and other Unix systems.

It provides a procedural interface based around filehandles opened on the audio device (usually /dev/dsp* for PCM audio).

It also defines constants for various ioctl calls and other things based on the OSS system header files, so you don't have to rely on .ph files that may or may be correct or even present on your system.

Currently, only the PCM audio input and output functions are supported. Mixer support is likely in the future, sequencer support less likely.

EXPORTS

The main exports of Audio::OSS are rubber, tea, and tractor parts.

Seriously, though, nothing is exported by default. However, there are three export tags which cover the vast majority of things you might conceivably want, and which exist on most systems. These are:

:funcs

This tag imports the following functions, which perform various operations on the PCM audio device:

dsp_sync
dsp_reset
dsp_get_caps
set_sps
set_fmt
get_supported_fmts
set_fragment
get_outbuf_ptr
get_inbuf_ptr
get_outbuf_info
get_inbuf_info

:formats

This tag imports the following constants, which correspond to arguments to the set_fmt and bits in the return value from get_supported_fmts:

AFMT_QUERY
AFMT_S16_NE
AFMT_S16_LE
AFMT_S16_BE
AFMT_U16_LE
AFMT_U16_BE
AFMT_U8
AFMT_MU_LAW
AFMT_A_LAW

:caps

This tag imports the following constants, which correspond to bits in the return value from dsp_get_caps:

DSP_CAP_REVISION
DSP_CAP_DUPLEX
DSP_CAP_REALTIME
DSP_CAP_BATCH
DSP_CAP_COPROC
DSP_CAP_TRIGGER
DSP_CAP_MMAP
DSP_CAP_MULTI
DSP_CAP_BIND

The full list of constants and functions which can be imported from this module follows. Note that not all of these may be available on your system. When you build this module, the Makefile.PL will try to find them all, leaving out any that fail. To some extent, these are documented in the system header files, specifically <sys/soundcard.h> or <linux/soundcard.h>.

SNDCTL_DSP_RESET
SNDCTL_DSP_SYNC
SNDCTL_DSP_SPEED
SNDCTL_DSP_STEREO
SNDCTL_DSP_GETBLKSIZE
SNDCTL_DSP_SAMPLESIZE
SNDCTL_DSP_CHANNELS
SNDCTL_DSP_POST
SNDCTL_DSP_SUBDIVIDE
SNDCTL_DSP_SETFRAGMENT
SNDCTL_DSP_GETOSPACE
SNDCTL_DSP_GETISPACE
SNDCTL_DSP_NONBLOCK
SNDCTL_DSP_GETCAPS
SNDCTL_DSP_GETFMTS
SNDCTL_DSP_SETFMT
SNDCTL_DSP_GETTRIGGER
SNDCTL_DSP_SETTRIGGER
SNDCTL_DSP_GETIPTR
SNDCTL_DSP_GETOPTR
SNDCTL_DSP_MAPINBUF
SNDCTL_DSP_MAPOUTBUF
SNDCTL_DSP_SETSYNCRO
SNDCTL_DSP_SETDUPLEX
SNDCTL_DSP_GETODELAY

SNDCTL_DSP_GETCHANNELMASK
SNDCTL_DSP_BIND_CHANNEL
SNDCTL_DSP_PROFILE

SOUND_PCM_READ_RATE
SOUND_PCM_READ_CHANNELS
SOUND_PCM_READ_BITS
SOUND_PCM_READ_FILTER

AFMT_QUERY
AFMT_MU_LAW
AFMT_A_LAW
AFMT_IMA_ADPCM
AFMT_U8
AFMT_S16_LE
AFMT_S16_BE
AFMT_S16_NE
AFMT_S8
AFMT_U16_LE
AFMT_U16_BE
AFMT_MPEG
AFMT_AC3

DSP_CAP_REVISION
DSP_CAP_DUPLEX
DSP_CAP_REALTIME
DSP_CAP_BATCH
DSP_CAP_COPROC
DSP_CAP_TRIGGER
DSP_CAP_MMAP
DSP_CAP_MULTI
DSP_CAP_BIND

PCM_ENABLE_INPUT
PCM_ENABLE_OUTPUT

DSP_BIND_QUERY
DSP_BIND_FRONT
DSP_BIND_SURR
DSP_BIND_CENTER_LFE
DSP_BIND_HANDSET
DSP_BIND_MIC
DSP_BIND_MODEM1
DSP_BIND_MODEM2
DSP_BIND_I2S
DSP_BIND_SPDIF

APF_NORMAL
APF_NETWORK
APF_CPUINTENS

BUGS

As mentioned above, the mixer interface is not supported.

The Makefile.PL is pretty slow, and could be optimized to check more than one constant at once, or all of them at once, even.

There is no object oriented interface (this is a feature, in my opinion).

The documentation is lacking, but then, that's also true for OSS itself.

AUTHOR

David Huggins-Daines <dhd@cepstral.com>

SEE ALSO

perl(1), /usr/include/sys/soundcard.h