[mythtv-users] Transcoding and aspect ratio (DVB-T)

[Ian Grant]

Osma Ahvenlampi wrote:
> On ma, 2006-02-27 at 04:57 -0500, Chris Pinkham wrote:
>   
> I think the issue is that since MPEG-2 contains the aspect ratio on a
> per-frame level or at least embedded into the stream multiplex in any
> point, the aspect may change during recording. It routinely does in the
> Finnish DVB-T transmissions, where it can be for example that a movie is
> broadcasted in 16:9, but the commercial breaks are in 4:3 (which
> incidentally makes it really easy for the commercial detection code to
> work). 
>
> As I guess the nuv container only contains the aspect information in the
> beginning of the stream (which technically makes it not a stream, btw),
> mythtranscode picks the first available aspect information from the
> stream and uses that. What may easily happen is that since the recording
> usually begins a couple of minutes prior to program change, the first
> data is incorrect - and during transcoding the later correct data is
> thrown away.
>
> I've found that when I make a cutlist before transcoding and ensure that
> the post-cutlist program starts from the point where the aspect ratio
> matches the real recording content, whether 4:3 or 16:9, the transcoded
> MPEG4 .nuv is correct. If I just let the transcoder work on the whole
> recording, I'll have to override aspect ratio during playback.
>   
I'll try that and see what happens, but for me the problem occurs even
when the first frame of the recording is 16:9.