scrcpy/doc/audio.md
megapro17 4857c5dd59 Add support for FLAC audio codec
PR #4410 <#https://github.com/Genymobile/scrcpy/pull/4410>

Co-authored-by: Romain Vimont <rom@rom1v.com>
Signed-off-by: Romain Vimont <rom@rom1v.com>
2023-11-15 12:02:57 +01:00

3.9 KiB

Audio

Audio forwarding is supported for devices with Android 11 or higher, and it is enabled by default:

  • For Android 12 or newer, it works out-of-the-box.
  • For Android 11, you'll need to ensure that the device screen is unlocked when starting scrcpy. A fake popup will briefly appear to make the system think that the shell app is in the foreground. Without this, audio capture will fail.
  • For Android 10 or earlier, audio cannot be captured and is automatically disabled.

If audio capture fails, then mirroring continues with video only (since audio is enabled by default, it is not acceptable to make scrcpy fail if it is not available), unless --require-audio is set.

No audio

To disable audio:

scrcpy --no-audio

To disable only the audio playback, see no playback.

Audio only

To play audio only, disable the video:

scrcpy --no-video
# interrupt with Ctrl+C

Without video, the audio latency is typically not criticial, so it might be interesting to add buffering to minimize glitches:

scrcpy --no-video --audio-buffer=200

Source

By default, the device audio output is forwarded.

It is possible to capture the device microphone instead:

scrcpy --audio-source=mic

For example, to use the device as a dictaphone and record a capture directly on the computer:

scrcpy --audio-source=mic --no-video --no-playback --record=file.opus

Codec

The audio codec can be selected. The possible values are opus (default), aac, flac and raw (uncompressed PCM 16-bit LE):

scrcpy --audio-codec=opus  # default
scrcpy --audio-codec=aac
scrcpy --audio-codec=flac
scrcpy --audio-codec=raw

In particular, if you get the following error:

Failed to initialize audio/opus, error 0xfffffffe

then your device has no Opus encoder: try scrcpy --audio-codec=aac.

For advanced usage, to pass arbitrary parameters to the MediaFormat, check --audio-codec-options in the manpage or in scrcpy --help.

For example, to change the FLAC compression level:

scrcpy --audio-codec=flac --audio-codec-options=flac-compression-level=8

Encoder

Several encoders may be available on the device. They can be listed by:

scrcpy --list-encoders

To select a specific encoder:

scrcpy --audio-codec=opus --audio-encoder='c2.android.opus.encoder'

Bit rate

The default audio bit rate is 128Kbps. To change it:

scrcpy --audio-bit-rate=64K
scrcpy --audio-bit-rate=64000  # equivalent

This parameter does not apply to RAW audio codec (--audio-codec=raw).

Buffering

Audio buffering is unavoidable. It must be kept small enough so that the latency is acceptable, but large enough to minimize buffer underrun (causing audio glitches).

The default buffer size is set to 50ms. It can be adjusted:

scrcpy --audio-buffer=40   # smaller than default
scrcpy --audio-buffer=100  # higher than default

Note that this option changes the target buffering. It is possible that this target buffering might not be reached (on frequent buffer underflow typically).

If you don't interact with the device (to watch a video for example), a higher latency (for both video and audio) might be preferable to avoid glitches and smooth the playback:

scrcpy --display-buffer=200 --audio-buffer=200

It is also possible to configure another audio buffer (the audio output buffer), by default set to 5ms. Don't change it, unless you get some robotic and glitchy sound:

# Only if absolutely necessary
scrcpy --audio-output-buffer=10