Re: tw68: Congratulations :-) and possible vsync problem :-(

[Michael <auslands-kv@gmx.de>]

Wow things are really moving fast here.

This morning there was a commit in git, which actually eliminates the below 
mentioned problem.

It, however, introduced another small problem. The pictures is wrongly 
cropped. There is the lower part missing (roughly 150-200 lines).

With the last version, I had the same problem, but was able to get the full 
picture with the option "normid=3". This is no longer working.

Otherwise, great work!

Michael


Michael wrote:

> Hello
> 
> I have tested a TW6805 based mini-pci card with the new tw68-v2 driver
> from git (22 January 2010).
> 
> First of all: Congratulations! It is really working great.
> 
> However, I noticed some frame errors here and then. It is not easy to
> identify what the reason is. It looks a bit like a buffer problem as it
> happens more often, if there is some load on the system.
> 
> Here is a simple way how I can reproduce the frame errors:
> 
> mplayer -framedrop -fs -vo x11 tv:// -tv
> device=/dev/video0:width=640:height=480:normid=3
> 
> With this command, cpu load goes to 100% on my low powered geode system.
> The frame errors are very obvious. It looks like a vsync problem as the
> wrong frames always start somewhere in the middle. There is no horizontal
> shift visible.
> 
> Reducing the image size:
> 
> mplayer -framedrop -fs -vo x11 tv:// -tv
> device=/dev/video0:width=320:height=240:normid=3
> 
> gives a drop in CPU load to 13%. No more frame errors.
> 
> Also using hardware accelerated video playback (xv) reduces CPU load to
> some 20% and removes the frame errors:
> 
> mplayer -framedrop -fs -vo xv tv:// -tv
> device=/dev/video0:width=640:height=480:normid=3
> 
> Still, even here, occasionally there are some frame errors, depending on
> what happens on the system. These can be induced as follows. Using this
> program:
> 
> mkfifo /tmp/mp
> mplayer -framedrop -fs -vf screenshot -vo xv tv:// -tv
> device=/dev/video0:normid=3 -slave -input file=/tmp/mp </dev/null
> >/dev/null
> 
> When this test prog runs, you can issue commands to mplayer, e.g.
> 
> echo pause > /tmp/mp
> 
> This pauses mplayer. A second
> 
> echo pause > /tmp/mp
> 
> starts mplayer again. Here the first frame shows the error.
> 
> The same happens if you issue:
> 
> echo screenshot 0 > /tmp/mp
> 
> This captures a screenshot and saves it into the current pwd. Again, when
> mplayer takes the shot, there comes one error frame (probably also wrong
> vsync).
> 
> 
> Btw. using instead a bttv based card all these tests run without frame
> errors.
> 
> Does this information help to identify and remove the bug?
> 
> Best regards
> 
> Michael