[mythtv] Ticket #4872: Detect if video is letterboxed and switch to corect fill mode

Kevin Kuphal kkuphal at gmail.com
Tue Mar 18 02:20:01 UTC 2008


On Mon, Mar 17, 2008 at 7:21 AM, Mårten Bohlin <mabo at mochc.net> wrote:

> On Wed, Mar 5, 2008 at 8:42 PM, MythTV <mythtv at cvs.mythtv.org> wrote:
> > #4872: Detect if video is letterboxed and switch to corect fill mode
> >
>  -------------------------------------+--------------------------------------
> >   Reporter:  Mårten <mabo at mochc.net>  |       Owner:  ijr
> >      Type:  enhancement              |      Status:  new
> >   Priority:  minor                    |   Milestone:  unknown
> >  Component:  mythtv                   |     Version:  0.21-fixes
> >   Severity:  medium                   |     Mlocked:  0
> >
>  -------------------------------------+--------------------------------------
>
> Some comments about the new version of the patch (version 6).
>
> I now do the detection on the pre-buffered frames. And this give me
> two advantages:
>  * Switches that are very shorter than the amount of pre-buffered
> frames are removed. This makes it smoother to watch. On my setup there
> seems to be about one second of pre-buffered frames.
>
>  * The switch can be done almost at the exact frame where the switch
> is detected. This also makes it look much better.
>
> The cons is that I have to write multi-threaded code. Something that I
> have not done i C before. I do not know how expensive locking a QMutex
> is considered to be. So I have tried to keep that to a minimum.
>
> So please try it out and let me know if it works.


Marten,

I tried this out on my SVN release (patches applied OK) but all I get in the
logs is "Detect letterbox failed, source is not YUV12" or something similar
to that and it doesn't detect anything.  My recordings are HD recordings
from an AverMedia A180 played back with XvMC decoding using Nvidia drivers
on an FX5200

Kevin
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