playback timing doesn't match recording

[Alan Pope 🍺🐧🐱 🦄]

I've started Istanbul, set the preferences to create an ogg on the fly at the maximum resolution of my desktop (but it does the same at any resolution). I then click the icon to start recording. I move the mouse slowly around the screen as if to highlight things in my demo. (I later plan to add an audio track describing what I've done - so timing is important). When I playback the resultant OGG it zipps by at maximum warp, not the sedate speed I recorded at. It's fully reproducible.

[Alan Pope 🍺🐧🐱 🦄 (popey)]

Further to this I have performed some more tests:

http://popey.com/istanbul/demo1.ogg

alan@hactar:~$ file demo1.ogg
demo1.ogg: Ogg data, Theora video
alan@hactar:~$ ls -ltr demo1.ogg
-rw-r--r-- 1 alan alan 114351 2006-06-12 22:39 demo1.ogg

You can see the issue when you play back the video above. I start the video "on the minute" with seconds showing on the clock. Time passes quickly in the video. Also note the mouse cursor is yellow.

Before recording I killed powernowd and "echo 1024 > /proc/sys/dev/rtc/max-user-freq" as root, as this was suggested when playing back video to stabilise timing. Neither made any difference.

The PC on which I am performing this is a 2.1GHz Dell XPS Inspiron using the binary nvidia drivers.

I then attempted to test using the same computer but with the open nv video driver.

http://popey.com/istanbul/demo2.ogg

alan@hactar:~$ file demo2.ogg
demo2.ogg: Ogg data, Theora video
alan@hactar:~$ ls -ltr demo2.ogg
-rw-r--r-- 1 alan alan 118750 2006-06-12 22:51 demo2.ogg

I started this video at 30 seconds past but nothing was captured for a few seconds, then it skips chunks, not recording. Possibly the nv driver can't keep up where the binary/closed one can?

Hope this extra information helps.

Cheers,
Al,

[Alan Pope 🍺🐧🐱 🦄 (popey)]

Further test. By running gst-launch-0.10 to manually do what istanbul does (effectively) the timing is still "off". Here's the command line (taken directly from the ximagesrc documentation [0]).

$ gst-launch-0.10 -v ximagesrc ! video/x-raw-rgb,framerate=10/1 ! ffmpegcolorspace ! theoraenc ! oggmux ! filesink location=desktop.ogg

Does this make it a gstreamer issue?

[0] http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-good-plugins/html/gst-plugins-good-plugins-ximagesrc.html