Stutter in audio when changing playback speed (+ / -)
Since forever the audio playback on VLC stutters or locks up up for about 1/10 of a second when changing the speed of playback with keypad-+ and keypad-minus. The transition is never smooth. I have noticed this on video and audio-only mp3 playback. I suspect that the speed change is not queued into the data stream, but executed immediately, so that there is a synchronisation problem.
When I press "+" while playing a MP3, vlc -vvv spews this debug output:
[00007f49b0006f60] scaletempo audio filter debug: 1.501 scale, 1986.480 stride_in, 1323 stride_out
[000055af1c5ac6a0] main audio output warning: playback way too late (442437): flushing buffers
[000055af1c5ac6a0] vlcpulse audio output debug: write index corrupt
[000055af1c5ac6a0] pulse audio output debug: cannot synchronize start
[000055af1c5ac6a0] pulse audio output debug: deferring start (765747 us)
[000055af1c5ac6a0] vlcpulse audio output debug: write index corrupt
[000055af1c5ac6a0] pulse audio output debug: cannot synchronize start
[000055af1c5ac6a0] pulse audio output debug: deferring start (764436 us)
[000055af1c5ac6a0] vlcpulse audio output debug: write index corrupt
[000055af1c5ac6a0] pulse audio output debug: cannot synchronize start
[000055af1c5ac6a0] pulse audio output debug: deferring start (764245 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (662972 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (662884 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (662798 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (662743 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (662332 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (661930 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (652406 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (632033 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (630797 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (600716 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (600310 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (531766 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (518886 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (518469 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (488053 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (406475 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (405302 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (375069 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (373900 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (331269 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (275951 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (245718 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (244453 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (164869 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (164041 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (133895 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (81850 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (50822 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (20667 us)
[000055af1c5ac6a0] pulse audio output debug: deferring start (20129 us)
[000055af1c5ac6a0] pulse audio output debug: starting deferred
[000055af1c5ac6a0] pulse audio output debug: started
[000055af1c5ac6a0] main audio output warning: playback way too early (-381485): playing silence
[000055af1c5ac6a0] main audio output debug: inserting 16823 zeroes
Those inserted zeroes are most likely the stutter.
Version information:
VLC media player 3.0.9.2 Vetinari (revision 3.0.9.2-0-gd4c1aefe) VLC version 3.0.9.2 Vetinari (3.0.9.2-0-gd4c1aefe) Compiled by buildd on lgw01-amd64-060.buildd (Apr 9 2020 19:29:44) Compiler: gcc version 9.3.0 (Ubuntu 9.3.0-10ubuntu2)
(apologies for the bad formatting of this ticket)