[MPlayer-users] NTSC TV not shown at 30fps?

[Matthew Nichols]

When I view NTSC TV with MPlayer, it appears as though I'm not seeing the
full 30fps. It looks very much like a 25fps PAL broadcast (very similar to
some of the football broadcasts from Europe).

If I shut down mplayer and use tvtime instead, the video is clearly much 
more "fluid".

So, is the TV module, for some reason, not grabbing data from the TV card 
often enough? If I run mencoder, it captures at 30 fps, but the resulting 
video clip is also not as fluid as it should be.

I can think of two possible problems:

1] Data is only being read from the TV card at 25 fps (hard-coded for 
PAL).

However, I went through the code and printed out the various fps variables 
and they all say 29.97, so if 1] is the problem, then it's not obvious.

2] Data is only being captured 29.97 instead of 59.94 times per second, so 
only the odd or even fields are being grabbed.

This doesn't seem plausible though, because there's no missing detail on 
the resulting output (which would be what it might look like if the even 
or odd fields were always left out).

Does anybody have NTSC video that they can test this out with and verify 
my problem? I'd think someone would have noticed this by now, but maybe 
all the developers use PAL? :)

This is the command I use:

./mplayer -tv driver=v4l:norm=ntsc:chanlist=us-cable:channels=2-CBC,13-CNN,7-ABC:width=640:height=480 tv://2

I tried this with both the 0.91 and 1.0Pre2 versions and both have the 
same issue. If it's helpful I could include the verbose output from 
MPlayer, but looking through it I don't see anything of value. I really 
think it's an issue with the code that grabs data from the TV card.

./matt