[mythtv-users] read audio: File descriptor in bad state / Audio buffer overflow / Prebuffering pause

[Joe Hansche]

Any suggestions?

On Thu, 2005-01-20 at 22:30 -0700, Joe Hansche wrote:
> My mythtv setup has been working fairly well in the past.  0.15 was
> working very well for me at the time I had it, but a sound problem
> forced me to upgrade to 0.16, and other intermittent issues have been
> popping up since.  Those problems still exist in my current version,
> which is the CVS version 0.16.20041224-1, compiled from a fresh CVS
> download on Jan 19, 05.
> 
> This is what happens...  mythbackend will start recording a program, and
> it's doing fine.  Watching the recording, the video and audio are both
> good.  But something (I don't know what, but I'm hoping someone can help
> me pinpoint it) triggers a problem, and the backend is no longer able to
> read audio from the stream.  I get the messages:
> 
> 2005-01-20 20:13:28.411 NVR: Only read 1024 bytes of 4096 bytes from
> '/dev/dsp
> read audio: Success
> 2005-01-20 20:13:28.415 NVR: Only read -1 bytes of 4096 bytes from
> '/dev/dsp
> read audio: File descriptor in bad state
> 2005-01-20 20:13:28.416 NVR: Only read -1 bytes of 4096 bytes from
> '/dev/dsp
> read audio: File descriptor in bad state
> 
> repeated about 300 times per second (the average timestamp delta in the
> log is anywhere from 0.000 to 0.010 seconds).  The first message appears
> to be the final bit of data it receives from the audio buffer, and after
> that, it always returns "-1".  At that point, the backend begins using
> 100% CPU, and will continue doing so until the backend is restarted, or
> recording stops.  In the recording, audio becomes "stuck" so to speak,
> as if it's continuously repeating the last 300-500ms that it was able to
> read, and the video slows down to about 1/2 to 3/4 the original speed it
> should be.
> 
> I even tried exiting X, and letting it sit at a console terminal while
> recording, but it still happens, which leads me to believe it's not a
> load issue (ie: it isn't a problem with the backend being choked of
> resources due to something else hogging CPU or memory).
> 
> It doesn't seem to be dependent upon the channel, it happens equally as
> often on any channel that it's recording, and also happens while
> watching LiveTV sometimes.  That said, it is also not always
> reproducible.  In fact, after making a few changes (disabled XvMC,
> disabled opengl, switched from ALSA to OSS, and set both the backend and
> frontend to SUID root) it actually got a lot better, and several
> programs have been able to record without encountering this problem at
> all, but it does still exist.  One program recorded this evening at 5pm,
> and had no problems, but another program recorded at 7pm and I had to
> restart the backend about 5 times in 30 minutes before I decided to
> cancel the recording.
> 
> When watching a recording that has been affected by this in the
> frontend, when it hits the point that the problem begins, it starts
> spitting these messages to the console:
> 
> 2005-01-20 22:02:57.981 prebuffering pause
> 2005-01-20 22:05:17.092 Audio buffer overflow, audio data lost!
> 2005-01-20 22:05:17.283 Audio buffer overflow, audio data lost!
> 2005-01-20 22:05:17.881 Audio buffer overflow, audio data lost!
> 2005-01-20 22:05:18.551 Audio buffer overflow, audio data lost!
> 
> The prebuffering pause message came about 2 minutes sooner, but the
> playback was still okay after that, until the buffer overflow messages
> begin.
> 
> What can I do to help pinpoint whats causing this, and fix whatever it
> is?  Hardware and version information is:
> 
> CPU: 2.53GHz P4
> Mem: 512MB
> Kernel: 2.6.9-gentoo-r6 (gentoo development sources)
> ALSA: 1.0.6 (I know 1.0.8 is released, but I don't know how to patch the
> kernel to use the latest version ... does anyone else?)
> MythTV: 0.16 (cvs 20041224-1)
> Tuner: Hauppauge WinCast/TV (old, using bt848 chip, bttv module)
> Video Card: nVidia GeForce4 Ti 4400 (nvidia binary driver 1.0.6629)
> X: X.org 6.8.0-r4, configured with Xinerama for TV out
> Sound Card: Turtle Beach Santa Cruz (Cirrus Logic CS 4614/22/24, ALSA
> driver = cs46xx)
> 
> Not sure what else is needed, but I'll provide any details you think may
> be necessary .. just let me know and I'll get it.
> 
> Thanks,
> Joe
> -- 
> madCoder
> <madCoder at GameSurge.net>
> GameSurge, Inc.
> http://www.gamesurge.net/
> [ SupportCOM | WebCom | GSDev | Routing | AUPEG ]
> 
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users