[mythtv-users] Permanently overriding aspect ratio for specific recordings

Karl Dietz dekarl at spaetfruehstuecken.org
Tue Aug 20 14:26:16 UTC 2013


On 20.08.2013 16:05, Marius Schrecker wrote:
>
> On Tuesday, August 20, 2013 15:30 CEST, "Michael T. Dean"
> <mtdean at thirdcontact.com> wrote:
>
>     On 08/20/2013 05:00 AM, Marius Schrecker wrote:
>      > Hi again,
>      >
>      > For a period, my set top box was spitting out to my hd-pvr in the
>      > wrong format (4:3 instead of 16:9). This was handled okay by the tv,
>      > but the recordings made during this time are all windowboxed and
>      > compressed horizontally.
>
>     Note, too, that it's possible--depending on how it's broken--that fixing
>     the videos may be as simple as changing the display aspect ratio in the
>     stream (i.e. may not require actually decoding/scaling/re-encoding the
>     video). I don't know which tools are best to use to do this, though.

> I'll poke around in the files themselves to see if the aspect can be
> patched there.

see DVB Document A154 on frame compatible plano-stereoscopic DVB-3DTV
Annex B: HDTV service compatibility. [1]

Basically you fiddle with the H.264 bitstream to enable frame cropping
and change the sample aspect ratio.

The sample aspect ratio would be the same value as anamorphic HDTV
16:9 in 1440x1080 pixels. Then enable cropping and set proper offsets.

I have no idea if our player supports that. So a small sample from such
a file could go into the our sample file collection.

Regards,
Karl

[1] http://www.dvb.org/technology/standards/a154_DVB-3DTV_Spec.pdf


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