[MPlayer-users] Audio click when speed changed

Chris Crochet chris at weldtest.com
Sun May 18 04:19:09 CEST 2014

BUG: When the speed is changed during playback, a click occurs of varying
intensity, as if there was a discontinuity in the audio.

WHY THIS IS AN ISSUE FOR ME:  I'm using MPlayer in slave mode as a backend
for a custom player I'm writing, that synchronizes playback of the same
media file on two or more computers.  It does this primarily by making
frequent small adjustments to the speed, with the scaletempo filter
enabled.  Works great, except for the clicks.

* You do NOT need my custom player or any other frontend to replicate this
issue.  Run MPlayer from the command line, then rapidly and alternately
press [ and ] to hear the clicking.
* It occurs with both the current release Windows binary, and the updated
binary; I have not tested others platforms/versions.
* It occurs regardless of whether the scaletempo filter is enabled or not.
* In slave mode, it occurs with any speed command - speed_set, speed_incr,
and speed_mult.
* Interestingly, it occurs even if the command results in no actual change
in speed.  Even sending "speed_set 1" repeatedly will generate the clicks.
* It occurs with both the dsound and win32 audio output drivers; I have not
tested others.
* Setting "-mc 0" doesn't help.

My player was originally written with VLC as a backend.  It worked, and
without clicks, but I had issues with the unintelligent way VLC handles
caching.  While searching for a solution I discovered MPlayer.

Some brief initial tests seemed very promising, and I failed to notice the
clicking at that time.  So I proceeded to convert my player, and because I
did most of this with the audio off to avoid disturbing others in the room,
I only discovered the clicks when I'd almost completed the conversion.

I really don't want to go back to VLC, and my C skills are insufficient to
troubleshoot/modify/compile the MPlayer code.  So if anyone can help with
this issue, it would be greatly appreciated!

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