[mythtv-users] 1080i to 1080p Deinterlacing on Backend was Raspberry Pi now ships with 512MB RAM

[Paul Gardiner]

On 17/10/2012 04:34, Scott Knight wrote:
> on 10/16/2012 11:00 PM Michael T. Dean carved the following into a
> picnic table:
>> And, yes, a system that's transcoding everything to H.264 (versus
>> storing it in its native recording format) does make for an extremely
>> power hungry system.
>>
> You have just touched on something I have looked at a few times and
> never successfully figured out.  I already have a powerful backend (Xeon
> E3) with power to spare because it does other things like hosting VMs
> for building MythTV, cloud testing, etc.  It can commflag at 1200+ fps
> on 1080i content.  What I have noticed is that 1080i content looks
> pretty crappy no matter which deinterlacer I use on the frontends
> (mixture of ION, ION2, 9400, GT430 all running VDPAU).  720p content
> looks better and Blu-Ray looks stunning without even making the
> frontends break a sweat.
>
> Is there a way to take my 1080i recordings and just deinterlace them on
> the backend?  I don't care about transcoding out the commercials, don't
> care what format they end up in, don't care about disk space, as long as
> I can use whatever deinterlace algorithm looks best to my eyes when it's
> played.  Maybe I don't understand the limitations of 1080i
> deinterlacing, but it seems that with a good enough transcode, the end
> result should be somewhere between 720p and Blu-Ray.

I use the command below to convert 1080i50 stuff to 720p50. I'm in the
UK. Your recordings may be 1080i60, in which case you should change the
"-r 50" to "-r 60".

Also, a lot of 1080i50 transmissions are actually 1080p25, in which case
you don't want the deinterlacing at all.

/usr/bin/ffmpeg -i <infile> -vf 
crop=1920:1080:0:0,yadif=3,scale=1280:720 -vcodec libx264 -preset medium 
-profile high -crf 20.0 -r 50 -aspect 16:9 -acodec copy -f mp4 <outfile>