digital TV, 16:9 and 4:3 switching

[colinb]

I have about 2 hours of material which was broadcast on digital TV and I'd like to copy it to a DVD.

It switches several times between 4:3 and 16:9 and I need to decide how best to handle this.

As I understand it, a VTS can only hold video of one format (4:3 or 16:9) but not both. So I could split the footage at each transition between 4:3 and 16:9 (and vice versa) and put the resulting sections into a series of subsequent VTS's. I guess this would be OK but there tends to be a blank screen and silence of 4 or 5 secs while the DVD player moves from one VTS to another so it would look a bit messy - I'd prefer the transition to be as near insrtant as possible.

I suspect (though I haven't tried it yet) that if I just put the whole 2 hours into one VTS that the entire thing will playback at the same aspect ratio as the first frame (i.e if the first frame is 4:3 it will all playback as 4:3, and if the first frame was 16:9 it will all playback as 16:9). So half of the footage would either appear stretched or squashed.

Can anyone suggest the best way of authoring this to preserve the correct aspect ratio of it all, but with the shortest possible blank gaps between the transitions?

[scharfis_brain]

reencode it to 4x3 or 16x9.

you need to do this manually, for example using AVISynth.
Because you need to apply the resizing operation manually to the affected scenes.

[colinb]

Thanks. I forgot to add that it would be nice if I didn't have to re-encode any of it too! In the absence of any other clever authoring tricks I guess I'll have to though. There should be sufficient space on the DVD disk for me to re-encode the affected parts at a fairly high bitrate so that should mitigate any loss of quality in the re-encoding.

[scharfis_brain]

I suggest you to reencode to 16x9, cause there you won't stumble over major interlacing problems.

All you need to do with the 4x3 scenes, is to squeeze them horizontally with a factor of 0.75. and then add black bars at each side.

720 becomes 540
704 becomes 528
480 becomes 360
etc.

[colinb]

Thanks,

It looks like it's already been done for me. When watching the material it appeared to be switching from 16:9 to fullscreen 4:3. However, I've just extracted the data from the PVR and it's actually 16:9 all the way through. The 4:3 sections are centred with black bars on the left and right.

I can only assume that there are DAR instructions in the stream which tells the PVR to display the 16:9 data as widescreen or to cut out the centre 4:3 and display it fullscreen.