16:9 frames in a 4:3 DVB

[Instant Martian]

Hi guys,
here it is the issue: some DVB-T channels switch from 4:3 to 16:9 format during commercial breaks but they don't return to the correct format just when the show (or whatever) starts again, only after 1 or 2 seconds (sometimes even more), this resulting in a certain amount of frames with wrong AR at the beginning of the new "segment" after a break.
My goal is to author a DVD and I'm pretty sure this "mixed aspect ratio" will be a problem.
Is there a way to fix this thing so that all the frames have the same AR?

[manono]

My goal is to author a DVD and I'm pretty sure this "mixed aspect ratio" will be a problem.

Why would it be a problem? They all have the same resolution, don't they, 720x576 or whatever? Just set the DAR in your MPEG-2 encoder.

If you're not reencoding then yes, you may have a problem. Something like DVDPatcher should be able to give the whole thing the same DAR.

[Alex_ander]

Along with wrong flags, it sometimes happens in the very beginning of a 4:3 broadcast or just after a commercial, that about 100 frames have wrong proportions (after AR flags cure). I usually have to crop/resize/replace those frames (DGIndex-Avisynth-CCE-MVW). An example: recent 'Rolling Stones at the BBC' broadcast (problems in intro part: pillarboxed -> true 4:3 @ everything flagged as 16:9).

[Instant Martian]

Thanks for replying.

@manono
Actually I won't re-encode since Project-X gives me a .m2v stream.
I don't know DVDPatcher, it could be the right tool to use, I'll give it a look.

@Alex_ander
I don't know exactly how you "replace" those frames but from what I read re-encoding is involved and I would like to avoid it if possible.

[[_chef_]]

My goal is to author a DVD and I'm pretty sure this "mixed aspect ratio" will be a problem.

Why would it be a problem? They all have the same resolution, don't they, 720x576 or whatever? Just set the DAR in your MPEG-2 encoder.

Not true.
But for a continuous rec. it shouldnt matter.

[Instant Martian]

Thanks to you too [_chef_]. I realized that I forgot to mention an important point: my DVB-T receiver records the broadcast in a series of separate files (0001.MPG, 0002.MPG, ..., 000n.MPG) so the 16:9 frames can be in any of them. I don't know if DVDPatcher can handle this. Anyway I haven't had the time to try yet.

[misermidas]

For aspect ratio, you should try in projectX->presetting to set DAR to the aspect ratio of your movie ,I think it should set a fixed aspect ratio to your recording instead of a varying one (The adds would have the wrong aspect ratio but does that matter ?).

If I remember well,ProjectX can join multiple mpeg2 files to one single file ,I think I made that with .TS and .VOB files but not .MPG

Edit : forgot something: some DVB broadcasts use resolution like 544*576 that are not compliant to DVD ,you will have to re-encode in that case.

[Instant Martian]

Thanks misermidas.

For aspect ratio, you should try in projectX->presetting to set DAR to the aspect ratio of your movie ,I think it should set a fixed aspect ratio to your recording instead of a varying one (The adds would have the wrong aspect ratio but does that matter ?).

I will give it a try, as soon as I'm able to find the time (don't know when actually).
And no, not only the ads have the wrong AR, some frames of the "thing" (movie or whatever) too, I think it would take a lot of working to fix those frames (extract, resizing and reinserting them someway) so I think I'll live with that.

If I remember well,ProjectX can join multiple mpeg2 files to one single file ,I think I made that with .TS and .VOB files but not .MPG

It can. I load the series of MPEG files into ProjectX, cut out the ads and demux, it gives me two files: .m2v and .mp2, ready for authoring.

some DVB broadcasts use resolution like 544*576 that are not compliant to DVD ,you will have to re-encode in that case.

Never happened so far (luckily).

[AlanHK]

My HD decoder has AR settings at "auto", 16:9, letterbox, pan and scan, etc.

Auto follows what the TV station sets, but often that's wrong (at least for my primitive TV), and I end up with something both letterboxed and pillarboxed, so I manually set it.
If you can find a similar setting see if you can just fix it to widescreen or 4:3 regardless.

[Instant Martian]

If you can find a similar setting see if you can just fix it to widescreen or 4:3 regardless.

Problem is that the broadcasters keep switching from one AR to another so (I think) I'll end up with some wrong frames no matter how I set the receiver.
I'll look to see if there is a similar option on my receiver, but I'm afraid this is not the solution since the problem is in the broadcast itself.

[[_chef_]]

Yeah, there are standards and most of the broadcasters give a damn about it... that leads to problems which Instand Martian describes...

And even each reception device will handle such non-standard stuff differently..its a mess.

IM, have you tried with DVDlab (even trial version) or TMPGENC Author?

[Instant Martian]

No I haven't. DVDlab and TMPGENC Author are authoring software, I don't know how (and if) they could be used to fix this issue.

[[_chef_]]

Hi guys,
...
My goal is to author a DVD and I'm pretty sure this "mixed aspect ratio" will be a problem.
Is there a way to fix this thing so that all the frames have the same AR?

I thought that's exactly what you wanted...

[Instant Martian]

Yes, that's what I want but I start authoring only after I have all the assets ready and flawless.
What I mean is I don't know if they can be used to fix this kind of problem.

[Lowlander]

Martian,
I use Project-X for pre-processing my (SD) recordings, too. There is a setting for aspect ratio in the video section which affects the overall properties of the demuxed output files, and there is an aspect ratio setting in the editing window, which activates some kind of A/R filter.

If I demux a mixed A/R TS recording, which has 4:3 video (Columbo, Kojak, other cool 70s stuff) and 16:9 teasers/commercials, only true 4:3 frames are kept, all other frames are discarded on the way. I can live with losing some 4:3 frames, which were incorrectly flagged as 16:9. Project-X is capable of getting rid of each and every 16:9 frame automatically, which gives me a clean 4:3 stream.

After that I use Cuttermaran to trim and manually remove any leftover teaser/commercial frames where the 4:3 AR flag was switched on/off too early/late.

[Instant Martian]

Lowlander, thanks a lot for your helpful reply, I didn't know that. It could be the solution in most of the cases but sometime the number of "wrong" frames is too high to simply cut them away or even worse, they keep switching from one AR to another for a few seconds into the show, after a commercial break. In that case I think I'll have to live with it and leave the frames as they are, but I'll keep in mind your tip, it's very useful. Thanks again.