[MPlayer-dev-eng] [PATCH] Bug fix in af_add/del/switch/clr

[Jehan Pagès]

Hi,

I have been recently noticed by a user of a bug with audio filter
loading-on-the-run commands. Some audio frames were lost, which was
unnoticed when used punctually, but when loading/reloading/clearing a
lot filters in some time span, more frames lost became noticeable,
hence speed was accelerating. And consequently some videos were not
resyncing well, so images and audios got desynchronized.

Though it seems unlikely to load filters every few milliseconds to
notice this, the user who reported the bug used an audio equalizer
filter reloading. I guess such an equalizer could be very often
reloaded by a mplayer GUI while a user is trying to find the right
values to apply to each frequency band (I guess this person was indeed
developping some GUI to mplayer). And he wants to do this without
music speeding or video desyncing. And anyway that's a bug, so it is
good to fix. :-)
After test, the problem occurred with any audio filter anyway.

-------------------
To reproduce:

$ mkinfo /tmp/fifompdev
$ mplayer  -slave -input file=/tmp/fifompdev <your_media_file>
$ while true ; do echo af_switch equalizer=0:0:0:0:0:0:0:0:1:1
>/tmp/fifompdev; sleep 0.1; done

What happens and should not: in an audio file, the music will
accelerate. In a video file, audio and video may desync.
-------------------

Basically to fix, I removed calls to reinit_audio_chain(); after such
a dynamic load/unload of a filter. This was causing the issue and this
was an unecessary call actually as any sound reinitialization was
already dealed with in the functions which actually loaded/unloaded
audio filters.

Attached is the small patch file.
You can try the bug reproduction before and after, and confirms it has
been fixed (I confirmed it on my machine and the user who reported me
the bug also did for him).
Thanks.

Jehan
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