[mythtv] Stutter mostly (but not quite) gone with 01/08 CVS

[Joshua M. Thompson]

Running CVS as of late yesterday i am finding that although the 
stuttering video is mostly gone, it still pops back on occasion for my 
MPEG-2 recordings and occurs every time when trying to play recordings 
transcoded to MPEG-4.

Background info:

FC2 running 2.6.8-1.521
MythTV CVS head as of 1/8 5pm EST
Nvidia GeForce FX, driver version 6111
PVR 350 (hardware encode only; decode not used), ivtv 0.2.0-rc3c.
Turtle Beach Riviera

First I should note that I now have to run with "Extra audio buffering" 
enabled or my video stutters. Before upgrading from 11/15 CVS I did not 
need to set this.

Watching normal live TV or untranscoded recordings normally plays fine, 
although on occasion I get stuttering that goes away if I stop playback 
and restart it again.

Watching transcoded MPEG-4 recordings causes stutter every time. Running 
them from the command line I get the following output:

2005-01-09 22:55:09.535 Joystick disabled.
2005-01-09 22:55:09.950 detectInterlace(Detect Scan, Detect Scan, 29.97, 
480) ->Interlaced Scan
2005-01-09 22:55:09.950 Interlaced: Interlaced Scan  video_height: 480 
fps: 29.97
Invalid seektable (frametype 4)
2005-01-09 22:55:10.899 Estimated bitrate = 0
2005-01-09 22:55:10.902 SyncPositionMap prerecorded, from DB: 0 entries
2005-01-09 22:55:10.914 Opening audio device 'digital'.
2005-01-09 22:55:10.954 Over/underscan. V: 0, H: 0, XOff: 0, YOff: 0
2005-01-09 22:55:10.967 Using XV port 105
2005-01-09 22:55:10.981 Image size. dispxoff 6, dispyoff: 0, dispwoff: 
787, disphoff: 600
2005-01-09 22:55:10.981 Image size. imgx 0, imgy: 0, imgw: 720, imgh: 480
2005-01-09 22:55:11.699 Realtime priority would require SUID as root.
2005-01-09 22:55:11.701 Changing from None to WatchingPreRecorded
2005-01-09 22:55:11.834 nVidiaVideoSync: VBlank ioctl did not work, 
unimplemented in this driver?
2005-01-09 22:55:11.867 DRMVideoSync: Could not open device 
/dev/dri/card0, No such device or address
2005-01-09 22:55:11.870 OpenGLVideoSync: GLX extensions: 
GLX_EXT_visual_info GLX_EXT_visual_rating GLX_SGIX_fbconfig 
GLX_SGIX_pbuffer GLX_SGI_video_sync GLX_SGI_swap_control 
GLX_ARB_get_proc_address
2005-01-09 22:55:11.918 Using audio as timebase
2005-01-09 22:55:11.918 Video timing method: SGI OpenGL
2005-01-09 22:55:11.918 Refresh rate: 11745, frame interval: 33366
'video_output' mean = '33685.06', std. dev. = '2376.15', fps = '29.69'
2005-01-09 22:55:16.563 WriteAudio: buffer underrun
2005-01-09 22:55:16.607 A/V diverged by 30 frames, extending frame to 
keep audio in sync
2005-01-09 22:55:16.690 A/V diverged by 30 frames, extending frame to 
keep audio in sync

This continues on, repeating the A/V diverged messages inter spaced with 
the occasional buffer underrun message.

I have posted a short (25MB) clip from the beginning of one of the 
transcoded episodes to see if this is a transcoding error or a playback 
error. The file is at:

http://tokimi.jurai.org/~funaho/mpeg4_stutter.nuv

For me at least the stutter begins a few seconds into the video, almost 
exactly at the point where the Comedy Central logo goes off and the show 
starts.