Bug 30700

Summary:	[sound] Applications cannot synchronize sound using pcm(4) driver
Product:	Base System	Reporter:	Gary Thorpe <gat>
Component:	kern	Assignee:	freebsd-multimedia (Nobody) <multimedia>
Status:	Closed FIXED
Severity:	Affects Only Me
Priority:	Normal
Version:	Unspecified
Hardware:	Any
OS:	Any

Description Gary Thorpe freebsd_committer

2001-09-21 03:40:01 UTC

The pcm(4) sound driver does not seem to provide proper information for
synchronizing sound with other activities in user applications. This is
observed as a delay of 1-2 seconds between when the sound is supposed to
be heard and when it actually is heard. 

The SNES emulator snes9x (ported or compiled from source) shows this lag
when roms are being emulated: sound effects occur with a 1-2 second delay
after the corresponding action. Another application which can be used to
show this is mtvp or mtv (mpeg video player from www.mpegtv.com) which
runs on FreeBSD via linux emulation. The mpeg video being 
played also has a lag of 1-2 seconds between the sound output and the 
corresponding video. I have used both applications under linux without
this behaviour. Additonally, mtvp has several means of synchronizing
the sound with the video, but none seem to work (the best one has the
lag problem).

How-To-Repeat: Use an application which requires sound to be synchronized with video
or some other output. You should notice a "phase shift" between the
video and audio.

Comment 1 Kris Kennaway freebsd_committer

2002-01-06 04:30:52 UTC

Responsible Changed
From-To: freebsd-bugs->sound

Sound issue

Comment 2 Alexander Leidinger freebsd_committer

2005-09-11 13:54:37 UTC

State Changed
From-To: open->closed

Current multimedia applications (like mplayer or xine) don't have a problem. 

In case this is still a problem with 5.[34] or -current, open a new 
bug report with the output of "pciconf -v -l" and "cat /dev/sndstat".