[mythtv-users] How can I tell the native X/Y size of a recorded file?

Michael T. Dean mtdean at thirdcontact.com
Mon Apr 7 14:56:31 UTC 2008


On 04/07/2008 10:27 AM, Mark Knecht wrote:
> Assume I've already recorded some material and the file resides on my
> backend server. How can I tell what the native X/Y video size of that
> file is?
>   

mplayer -v -v -v -v -nolirc -nojoystick \
        -vo null -ao null -frames 1 \
        -identify '/path/to/recording.mpg' 2>&1 |
tee ~/mplayer_identify_output

You'll get a ton of output, but really the important stuff is at the
bottom.  The above will throw a copy of the output into a file so you
can browse through it more easily (especially if you don't have a big
scroll buffer in your terminal).

> I'm assuming that to reduce the CPU usage on the frontend that is
> displaying this file it would be better if I didn't rescale the
> recorded file but actually set the resolution of the display screen to
> the same resolution. Is this true?

If you're using Xv or XvMC, scaling if basically free as it's done by
the GPU.

>  If so I'd like to try two things:
>
> 1) Playing the file full screen after resetting X to run at that
> resolution. (If possible)
>
> 2) Start mythfrontend with --geometry set to those values.
>
> Just wanted to try an experiment to see how it impacts CPU usage.

If you do want to set Myth to output the video's native size, you should
set it up to use Xrandr, then it will switch automatically.  Of course
this means that your TV's scaler will be used instead.  IMHO, this is a
bad thing since you have 0 control over the TV's scaler, but you have a
lot of control over Myth's.

Mike



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