mpv-skipsilence

Increase playback speed during silence - a revolution in attention-deficit induction technology.

Main repository: https://codeberg.org/ferreum/mpv-skipsilence/

Based on the script https://gist.github.com/bitingsock/e8a56446ad9c1ed92d872aeb38edf124

This is inspired by the NewPipe app's built-in "Fast-forward during silence" feature.

Note: In mpv version 0.36 and below, the scaletempo2 filter (default since mpv version 0.34) caused audio-video de-synchronization when changing speed a lot. This has been fixed in mpv 0.37. See mpv issue #12028. Small, frequent speed changes instead of large steps may help to reduce this problem. The scaletempo and rubberband filters didn't have this problem, but have different audio quality characteristics.

Features:

• Parameterized speedup ramp, allowing profiles for different kinds of media (ramp_*, speed_*, startdelay options).
• Noise reduction of the detected signal. This allows to speed up pauses in speech despite background noise. The output audio is unaffected by default (arnndn_* options).
• Saved time estimation.
• Integration with osd-msg, auto profiles, etc. (with user-data, mpv 0.36 and above only).
• Experimental: Lookahead for dynamic slowdown and faster reaction time (lookahead, slowdown_ramp_*, margin_* options).
• Workaround for scaletempo2 audio-video desynchronization in mpv 0.36 and below (resync_threshold_droppedframes option).
• Workaround for clicks during speed changes with scaletempo2 in mpv 0.36 and below (alt_normal_speed option).

Silence detection visualized

The following graph shows an example silence detection and resulting playback speed, annotated with options that impact speed changes.

If the experimental lookahead option is set to a positive value, the effect of some options changes:

¹⁾ Without lookahead, Silence Start is delayed by threshold_duration. If lookahead is active, it reduces this delay by up to that configured lookahead duration.

²⁾ minduration is only supported with lookahead.

³⁾ startdelay is ignored if lookahead is enabled and margin_start is used instead.

⁴⁾ The box marked if lookahead only applies if lookahead is active. Otherwise, the speed is reverted in a single step exactly at the time of Silence End detection.

Default bindings

• F2 - toggle
• F3 - threshold-down
• F4 - threshold-up

Documentation

For detailed usage check the comments at the top of the script.

Recommendations

Temporarily disable display sync

When using video-sync=display-*, speed changes tend to cause increased video lag. Because display sync is less useful while speed keeps changing, it's recommended to use video-sync=audio (the default) while this script is active. This results in smoother video playback during speed transitions.

The following profile can be used to automatically switch to video-sync=audio when skipsilence is enabled and restore it when disabled (requires mpv 0.36 or above for user-data):

[auto-skipsilence-videosync]
profile-cond=get("user-data/skipsilence/enabled")
profile-restore=copy-equal
video-sync=audio

Fix clicking sounds/gaps when switching to and from 1x speed

In the default configuration, mpv automatically inserts scaletempo2 filter when changing speed and removes it when returning to 1x playback speed. This often causes clicks in audio playback. To prevent this, add scaletempo2 to the af filter list explicitly:

af-add=scaletempo2

In mpv 0.36 and below, the scaletempo2 filter itself additionally caused similar artifacts when switching to and from 1x speed. This has been fixed in mpv 0.37. The alt_normal_speed option of this script is a workaround for older versions.

Fix silence at high playback speed

By default, scaletempo2 produces silence above 8x playback speed (4x in mpv 0.36 and below). To lift this limit, set the max-speed parameter in the filter definition (see above) like this:

af-add=scaletempo2=max-speed=16.0

Maximize skipping speed

Because of the asynchronous nature of scripts, there is latency between silence detection and speed changes. The higher the playback speed, the more noticeably playback will overshoot before normal speed is restored. What speeds are acceptable depends on the performance/latency of the system.

To maximize skipping speed, start with the extreme profile (see Profiles below). Then adjust ramp_constant, ramp_factor, max_speed options as needed.

• If overshooting happens all the time, even for very short pauses, reduce ramp_constant.
• If it happens after the speed ramped up more, focus on ramp_factor.
• For the occasional long stretch of silence this may be less of a problem, but can be improved by reducing max_speed at a cost of slower skipping.
• Notice that extreme values of ramp_exponent tend to be less useful. It's recommended to keep the ramp_exponent around 0.9 for aggressive profiles.

Lookahead

The experimental lookahead option makes much higher maximum speed practical by gradually slowing down before the end of silence is reached. See the lookahead, slowdown_ramp_* and margin_* options. To maximize skipping speed, use a slowdown ramp that is as steep as possible without overshooting on slowdown. margin_end can help, but is usually not required.

Profiles

Mpv's profiles can be used to switch between different presets. Create profiles in mpv.conf and apply them with the apply-profile command.

[skipsilence-default]
script-opts-append=skipsilence-ramp_constant=1.25
script-opts-append=skipsilence-ramp_factor=2.5
script-opts-append=skipsilence-ramp_exponent=1
script-opts-append=skipsilence-speed_max=4
script-opts-append=skipsilence-speed_updateinterval=0.05
script-opts-append=skipsilence-startdelay=0.05

Bind it to a key in input.conf:

F5 script-message-to skipsilence enable no-osd; apply-profile skipsilence-default; show-text "skipsilence profile: default"

Examples

# very smooth speed increase, up to 3x
[skipsilence-smooth]
script-opts-append=skipsilence-ramp_constant=1
script-opts-append=skipsilence-ramp_factor=0.4
script-opts-append=skipsilence-ramp_exponent=1.45
script-opts-append=skipsilence-speed_max=3
script-opts-append=skipsilence-speed_updateinterval=0.05
script-opts-append=skipsilence-startdelay=0
script-opts-append=skipsilence-threshold_duration=0.25

# very aggressive skipping, can make it hard to listen
[skipsilence-extreme]
script-opts-append=skipsilence-ramp_constant=2.5
script-opts-append=skipsilence-ramp_factor=10
script-opts-append=skipsilence-ramp_exponent=0.9
script-opts-append=skipsilence-speed_max=6
script-opts-append=skipsilence-speed_updateinterval=0.05
script-opts-append=skipsilence-startdelay=0
script-opts-append=skipsilence-threshold_duration=0.05

# long wait (1s) before speeding up quickly
[skipsilence-patient]
script-opts-append=skipsilence-ramp_constant=1.25
script-opts-append=skipsilence-ramp_factor=3
script-opts-append=skipsilence-ramp_exponent=0.9
script-opts-append=skipsilence-speed_max=4
script-opts-append=skipsilence-speed_updateinterval=0.05
script-opts-append=skipsilence-startdelay=0
script-opts-append=skipsilence-threshold_duration=1