mirror of
https://github.com/mpv-player/mpv
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f1072e7629
This partially reverts commit 7d152965. It turns out that at least some
ALSA drivers (at least snd-hda-intel) report incorrect audio delay with
non-native sample rates, even if the sample rate is only very slightly
different from the native one.
For example, 48000Hz is fine on my hda-intel system, while both 8000Hz
and 47999Hz lead to a delay off by 40ms (according to mpv's A/V
difference display), which suggests that something in ALSA is
calculating the delay using the wrong sample rate.
As an additional problem, with ALSA resampling enabled, using
48001Hz/float/2ch fails, while 49000Hz/float/2ch or 48001Hz/s16/2ch
work. With resampling disabled, all these cases work obviously, because
our own resampler doesn't just refuse any of these formats.
Since some people want to use the ALSA resampler (because it's highly
configurable, supports multiple backends, etc.), we still allow enabling
ALSA resampling with an ao_alsa suboption.
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AUDIO OUTPUT DRIVERS
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====================
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Audio output drivers are interfaces to different audio output facilities. The
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syntax is:
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``--ao=<driver1[:suboption1[=value]:...],driver2,...[,]>``
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Specify a priority list of audio output drivers to be used.
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If the list has a trailing ',', mpv will fall back on drivers not contained
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in the list. Suboptions are optional and can mostly be omitted.
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.. note::
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See ``--ao=help`` for a list of compiled-in audio output drivers.
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.. admonition:: Examples
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- ``--ao=alsa,oss,`` Try the ALSA driver, then the OSS driver, then others.
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- ``--ao=alsa:no-block:device=[hw:0,3]`` Sets noblock-mode and the
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device-name as first card, fourth device.
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Available audio output drivers are:
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``alsa`` (Linux only)
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ALSA audio output driver
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``no-block``
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Sets noblock-mode.
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``resample=yes``
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Enable ALSA resampling plugin. (This is disabled by default, because
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some drivers report incorrect audio delay in some cases.)
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``device=<device>``
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Sets the device name. For ac3 output via S/PDIF, use an "iec958" or
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"spdif" device, unless you really know how to set it correctly.
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``mixer-device=<device>``
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Set the mixer device used with ``--no-softvol`` (default: ``default``).
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``mixer-name=<name>``
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Set the name of the mixer element (default: ``Master``). This is for
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example ``PCM`` or ``Master``.
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``mixer-index=<number>``
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Set the index of the mixer channel (default: 0). Consider the output of
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"``amixer scontrols``", then the index is the number that follows the
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name of the element.
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.. note::
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MPlayer and mplayer2 required you to replace any ',' with '.' and
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any ':' with '=' in the ALSA device name. mpv does not do this anymore.
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Instead, quote the device name:
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``--ao=alsa:device=[plug:surround50]``
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Note that the ``[`` and ``]`` simply quote the device name. With some
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shells (like zsh), you have to quote the option string to prevent the
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shell from interpreting the brackets instead of passing them to mpv.
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``oss``
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OSS audio output driver
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``<dsp-device>``
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Sets the audio output device (default: ``/dev/dsp``).
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``<mixer-device>``
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Sets the audio mixer device (default: ``/dev/mixer``).
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``<mixer-channel>``
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Sets the audio mixer channel (default: ``pcm``). Other valid values
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include **vol, pcm, line**. For a complete list of options look for
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``SOUND_DEVICE_NAMES`` in ``/usr/include/linux/soundcard.h``.
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``jack``
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JACK (Jack Audio Connection Kit) audio output driver
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``port=<name>``
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Connects to the ports with the given name (default: physical ports).
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``name=<client>``
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Client name that is passed to JACK (default: ``mpv``). Useful
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if you want to have certain connections established automatically.
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``(no-)estimate``
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Estimate the audio delay, supposed to make the video playback smoother
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(default: enabled).
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``(no-)autostart``
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Automatically start jackd if necessary (default: disabled). Note that
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this tends to be unreliable and will flood stdout with server messages.
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``(no-)connect``
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Automatically create connections to output ports (default: enabled).
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When enabled, the maximum number of output channels will be limited to
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the number of available output ports.
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``std-channel-layout=alsa|waveext|any``
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Select the standard channel layout (default: alsa). JACK itself has no
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notion of channel layouts (i.e. assigning which speaker a given
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channel is supposed to map to) - it just takes whatever the application
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outputs, and reroutes it to whatever the user defines. This means the
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user and the application are in charge of dealing with the channel
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layout. ``alsa`` uses the old MPlayer layout, which is inspired by
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ALSA's standard layouts. In this mode, ao_jack will refuse to play 3
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or 7 channels (because these do not really have a defined meaning in
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MPlayer). ``waveext`` uses WAVE_FORMAT_EXTENSIBLE order, which, even
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though it was defined by Microsoft, is the standard on many systems.
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The value ``any`` makes JACK accept whatever comes from the audio
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filter chain, regardless of channel layout and without reordering. This
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mode is probably not very useful, other than for debugging or when used
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with fixed setups.
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``coreaudio`` (Mac OS X only)
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Native Mac OS X audio output driver
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``device_id=<id>``
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ID of output device to use (0 = default device)
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``help``
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List all available output devices with their IDs.
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``openal``
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Experimental OpenAL audio output driver
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``pulse``
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PulseAudio audio output driver
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``[<host>][:<output sink>]``
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Specify the host and optionally output sink to use. An empty <host>
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string uses a local connection, "localhost" uses network transfer
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(most likely not what you want).
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``portaudio``
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PortAudio audio output driver. This works on all platforms, and has
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extensive MS Windows support.
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``device``
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Specify the subdevice to use. Giving ``help`` as device name lists all
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devices found by PortAudio. Devices can be given as numeric values,
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starting from ``1``.
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``dsound`` (Windows only)
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DirectX DirectSound audio output driver
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``device=<devicenum>``
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Sets the device number to use. Playing a file with ``-v`` will show a
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list of available devices.
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``sdl``
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SDL 1.2+ audio output driver. Should work on any platform supported by SDL
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1.2, but may require the ``SDL_AUDIODRIVER`` environment variable to be set
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appropriately for your system.
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``buflen=<length>``
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Sets the audio buffer length in seconds. Is used only as a hint by the
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sound system. Playing a file with ``-v`` will show the requested and
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obtained exact buffer size. A value of 0 selects the sound system
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default.
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``bufcnt=<count>``
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Sets the number of extra audio buffers in mpv. Usually needs not be
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changed.
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``null``
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Produces no audio output but maintains video playback speed. Use
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``--ao=null:untimed`` for benchmarking.
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``untimed``
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Do not simulate timing of a perfect audio device. This means audio
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decoding will go as fast as possible, instead of timing it to the
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system clock.
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``buffer``
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Simulated buffer length in seconds.
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``outburst``
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Simulated chunk size in samples.
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``pcm``
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Raw PCM/WAVE file writer audio output
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``(no-)waveheader``
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Include or do not include the WAVE header (default: included). When
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not included, raw PCM will be generated.
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``file=<filename>``
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Write the sound to ``<filename>`` instead of the default
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``audiodump.wav``. If ``no-waveheader`` is specified, the default is
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``audiodump.pcm``.
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``rsound``
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Audio output to an RSound daemon
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``host=<name/path>``
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Set the address of the server (default: localhost). Can be either a
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network hostname for TCP connections or a Unix domain socket path
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starting with '/'.
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``port=<number>``
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Set the TCP port used for connecting to the server (default: 12345).
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Not used if connecting to a Unix domain socket.
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``sndio``
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Audio output to the OpenBSD sndio sound system
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(Note: only supports mono, stereo, 4.0, 5.1 and 7.1 channel
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layouts.)
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``device=<device>``
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sndio device to use (default: ``$AUDIODEVICE``, resp. ``snd0``).
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``wasapi``
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Audio output to the Windows Audio Session API.
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``device=<id>``
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Uses the requested endpoint instead of the system's default audio
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endpoint. Both the number and the ID String are valid; the ID String
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is guaranteed to not change unless the driver is uninstalled.
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Also supports searching active devices by name. If more than one
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device matches the name, refuses loading it.
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To get a list of the valid devices, give ``help`` as the id. The
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list is the same as the ``list`` suboption, but stops the player
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initialization.
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``exclusive``
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Requests exclusive, direct hardware access. By definition prevents
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sound playback of any other program until mpv exits.
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``list``
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Lists all audio endpoints (output devices) present in the system.
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