mpv/DOCS/man/ao.rst

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AUDIO OUTPUT DRIVERS
====================
Audio output drivers are interfaces to different audio output facilities. The
syntax is:
``--ao=<driver1,driver2,...[,]>``
Specify a priority list of audio output drivers to be used.
If the list has a trailing ',', mpv will fall back on drivers not contained
in the list.
.. note::
See ``--ao=help`` for a list of compiled-in audio output drivers. The
driver ``--ao=alsa`` is preferred. ``--ao=pulse`` is preferred on systems
where PulseAudio is used. On BSD systems, ``--ao=oss`` or ``--ao=sndio``
may work (the latter being experimental).
Available audio output drivers are:
``alsa`` (Linux only)
ALSA audio output driver
See `ALSA audio output options`_ for options specific to this AO.
.. warning::
To get multichannel/surround audio, use ``--audio-channels=auto``. The
default for this option is ``auto-safe``, which makes this audio output
explicitly reject multichannel output, as there is no way to detect
whether a certain channel layout is actually supported.
You can also try `using the upmix plugin <http://git.io/vfuAy>`_.
This setup enables multichannel audio on the ``default`` device
with automatic upmixing with shared access, so playing stereo
and multichannel audio at the same time will work as expected.
``oss``
OSS audio output driver
The following global options are supported by this audio output:
``--oss-mixer-device``
Sets the audio mixer device (default: ``/dev/mixer``).
``--oss-mixer-channel``
Sets the audio mixer channel (default: ``pcm``). Other valid values
include **vol, pcm, line**. For a complete list of options look for
``SOUND_DEVICE_NAMES`` in ``/usr/include/linux/soundcard.h``.
``jack``
JACK (Jack Audio Connection Kit) audio output driver.
The following global options are supported by this audio output:
``--jack-port=<name>``
Connects to the ports with the given name (default: physical ports).
``--jack-name=<client>``
Client name that is passed to JACK (default: ``mpv``). Useful
if you want to have certain connections established automatically.
``--jack-autostart=<yes|no>``
Automatically start jackd if necessary (default: disabled). Note that
this tends to be unreliable and will flood stdout with server messages.
``--jack-connect=<yes|no>``
Automatically create connections to output ports (default: enabled).
When enabled, the maximum number of output channels will be limited to
the number of available output ports.
``--jack-std-channel-layout=<waveext|any>``
Select the standard channel layout (default: waveext). JACK itself has no
notion of channel layouts (i.e. assigning which speaker a given
channel is supposed to map to) - it just takes whatever the application
outputs, and reroutes it to whatever the user defines. This means the
user and the application are in charge of dealing with the channel
layout. ``waveext`` uses WAVE_FORMAT_EXTENSIBLE order, which, even
though it was defined by Microsoft, is the standard on many systems.
The value ``any`` makes JACK accept whatever comes from the audio
filter chain, regardless of channel layout and without reordering. This
mode is probably not very useful, other than for debugging or when used
with fixed setups.
``coreaudio`` (Mac OS X only)
Native Mac OS X audio output driver using AudioUnits and the CoreAudio
sound server.
Automatically redirects to ``coreaudio_exclusive`` when playing compressed
formats.
The following global options are supported by this audio output:
``--coreaudio-change-physical-format=<yes|no>``
Change the physical format to one similar to the requested audio format
(default: no). This has the advantage that multichannel audio output
will actually work. The disadvantage is that it will change the
system-wide audio settings. This is equivalent to changing the ``Format``
setting in the ``Audio Devices`` dialog in the ``Audio MIDI Setup``
utility. Note that this does not affect the selected speaker setup.
``--coreaudio-spdif-hack=<yes|no>``
Try to pass through AC3/DTS data as PCM. This is useful for drivers
which do not report AC3 support. It converts the AC3 data to float,
and assumes the driver will do the inverse conversion, which means
a typical A/V receiver will pick it up as compressed IEC framed AC3
stream, ignoring that it's marked as PCM. This disables normal AC3
passthrough (even if the device reports it as supported). Use with
extreme care.
``coreaudio_exclusive`` (Mac OS X only)
Native Mac OS X audio output driver using direct device access and
exclusive mode (bypasses the sound server).
``openal``
OpenAL audio output driver
``--openal-num-buffers=<2-128>``
Specify the number of audio buffers to use. Lower values are better for
lower CPU usage. Default: 4.
``--openal-num-samples=<256-32768>``
Specify the number of complete samples to use for each buffer. Higher
values are better for lower CPU usage. Default: 8192.
``--openal-direct-channels=<yes|no>``
Enable OpenAL Soft's direct channel extension when available to avoid
tinting the sound with ambisonics or HRTF.
Channels are dropped when when they are not available as downmixing
will be disabled. Default: no.
``pulse``
PulseAudio audio output driver
The following global options are supported by this audio output:
``--pulse-host=<host>``
Specify the host to use. An empty <host> string uses a local connection,
"localhost" uses network transfer (most likely not what you want).
``--pulse-buffer=<1-2000|native>``
Set the audio buffer size in milliseconds. A higher value buffers
more data, and has a lower probability of buffer underruns. A smaller
value makes the audio stream react faster, e.g. to playback speed
changes.
``--pulse-latency-hacks=<yes|no>``
Enable hacks to workaround PulseAudio timing bugs (default: no). If
enabled, mpv will do elaborate latency calculations on its own. If
disabled, it will use PulseAudio automatically updated timing
information. Disabling this might help with e.g. networked audio or
some plugins, while enabling it might help in some unknown situations
(it used to be required to get good behavior on old PulseAudio versions).
If you have stuttering video when using pulse, try to enable this
option. (Or try to update PulseAudio.)
``--pulse-allow-suspended=<yes|no>``
Allow mpv to use PulseAudio even if the sink is suspended (default: no).
Can be useful if PulseAudio is running as a bridge to jack and mpv has its sink-input set to the one jack is using.
``sdl``
SDL 1.2+ audio output driver. Should work on any platform supported by SDL
1.2, but may require the ``SDL_AUDIODRIVER`` environment variable to be set
appropriately for your system.
.. note:: This driver is for compatibility with extremely foreign
environments, such as systems where none of the other drivers
are available.
The following global options are supported by this audio output:
``--sdl-buflen=<length>``
Sets the audio buffer length in seconds. Is used only as a hint by the
sound system. Playing a file with ``-v`` will show the requested and
obtained exact buffer size. A value of 0 selects the sound system
default.
``--sdl-bufcnt=<count>``
Sets the number of extra audio buffers in mpv. Usually needs not be
changed.
``null``
Produces no audio output but maintains video playback speed. You can use
``--ao=null --ao-null-untimed`` for benchmarking.
The following global options are supported by this audio output:
``--ao-null-untimed``
Do not simulate timing of a perfect audio device. This means audio
decoding will go as fast as possible, instead of timing it to the
system clock.
``--ao-null-buffer``
Simulated buffer length in seconds.
``--ao-null-outburst``
Simulated chunk size in samples.
``--ao-null-speed``
Simulated audio playback speed as a multiplier. Usually, a real audio
device will not go exactly as fast as the system clock. It will deviate
just a little, and this option helps to simulate this.
``--ao-null-latency``
Simulated device latency. This is additional to EOF.
``--ao-null-broken-eof``
Simulate broken audio drivers, which always add the fixed device
latency to the reported audio playback position.
``--ao-null-broken-delay``
Simulate broken audio drivers, which don't report latency correctly.
``--ao-null-channel-layouts``
If not empty, this is a ``,`` separated list of channel layouts the
AO allows. This can be used to test channel layout selection.
``--ao-null-format``
Force the audio output format the AO will accept. If unset accepts any.
``pcm``
Raw PCM/WAVE file writer audio output
The following global options are supported by this audio output:
``--ao-pcm-waveheader=<yes|no>``
Include or do not include the WAVE header (default: included). When
not included, raw PCM will be generated.
``--ao-pcm-file=<filename>``
Write the sound to ``<filename>`` instead of the default
``audiodump.wav``. If ``no-waveheader`` is specified, the default is
``audiodump.pcm``.
``--ao-pcm-append=<yes|no>``
Append to the file, instead of overwriting it. Always use this with the
``no-waveheader`` option - with ``waveheader`` it's broken, because
it will write a WAVE header every time the file is opened.
``rsound``
Audio output to an RSound daemon. Use ``--audio-device=rsound/<hostname>``
to set the host name (with ``<hostname>`` replaced, without the ``< >``).
.. note:: Completely useless, unless you intend to run RSound. Not to be
confused with RoarAudio, which is something completely
different.
``sndio``
Audio output to the OpenBSD sndio sound system
.. note:: Experimental. There are known bugs and issues.
(Note: only supports mono, stereo, 4.0, 5.1 and 7.1 channel
layouts.)
``wasapi``
Audio output to the Windows Audio Session API.