Deinterlace Pal 50i to 25p with single frame splitted in 2 fields

[phate89]

Hi... I usually reencode my tv 1080 50i recordings from tv to save space. I never bother to deinterlace this sources because usually the video is never truly interlaced, they simply split the progressive frame into 2 fields (so they get from 25 frames 50 fields, i don't know the right name for this interlacing method).
So i simply usually pass the ts to directshowsource and resize it to 1280x720 with avisynth without any other deinterlace. For example:
DirectShowSource("C:\video\tvshow.ts")
BlackmanResize(1280,720)
Is there a better method to handle sources like this? they have to be deinterlaced too or not? Can this method create problems with my videos?

[sneaker_ger]

This method is fine. Movies made for the cinema or newer (US) TV series are usually produced at 24 frames per second. For 50 Hz television they are sped a bit up to 25 fps and then one frame is divided into two fields for the 1080i25 broadcast. Since both fields are from the same original progressive frame (shot at the same time), deinterlacing is not necessary at all.

You still have to deinterlace true interlaced TV material, like e.g. sports, though.

[phate89]

This method is fine. Movies made for the cinema or newer (US) TV series are usually produced at 24 frames per second. For 50 Hz television they are sped a bit up to 25 fps and then one frame is divided into two fields for the 1080i25 broadcast. Since both fields are from the same original progressive frame (shot at the same time), deinterlacing is not necessary at all.

You still have to deinterlace true interlaced TV material, like e.g. sports, though.

And if i want to replace directshowsource with some better decoder like avcsource i can do it without changes? I usually go with ffms2 but with interlaced/ts material is not a good choice.

[sneaker_ger]

Yes, but the old avcsource is as bad as a source filter for tv broadcasts as ffms2. The only really good source filter for that is DGDecNV (http://neuron2.net/dgdecnv/dgdecnv.html), but it is not freeware and requires a suited Nvidia card.

[Mole]

I would use DGIndex to index it first though.

It is much more reliable to use than directshowsource and you will never have problem with audio/video synch or seeking problems.

[wonkey_monkey]

deinterlacing is not necessary at all.

Isn't there a (minor) chroma placement issue though?

David

[sneaker_ger]

Good point, though I have no idea if broadcasters actually stick to the spec in this regard. Hopefully someone with more insight can chime in on this.

[phate89]

I would use DGIndex to index it first though.

It is much more reliable to use than directshowsource and you will never have problem with audio/video synch or seeking problems.
The majority of europe hd transmissions are (luckily) in h264, not mpeg2...


Yes, but the old avcsource is as bad as a source filter for tv broadcasts as ffms2. The only really good source filter for that is DGDecNV (http://neuron2.net/dgdecnv/dgdecnv.html), but it is not freeware and requires a suited Nvidia card.
Sadly i have an ati gpu, In your opinion is better avcsource or directshowsource? (ffms2 officially not support ts or interlaced h264)

[Guest]

AVCSource() will barf on PAFF streams. If that doesn't affect you (MBAFF is fine), then it's better than DirectShowSource().

Also have a look at DSS2(). It can be frame accurate if your PTS timestamps are continuous.

[phate89]

AVCSource() will barf on PAFF streams. If that doesn't affect you (MBAFF is fine), then it's better than DirectShowSource().

Also have a look at DSS2(). It can be frame accurate if your PTS timestamps are continuous.

how can i detect this? I tried passing a video file (not one of my usual channel but should be the same) with dgcavcindex it returns sometimes MBAFF sometimes fields (TFF)

[Guest]

If you see video corruption then you have the PAFF problem.

[phate89]

If you see video corruption then you have the PAFF problem.

I see the preview in avisynth and have some frame that it's definitely corrupted... I'll try dss2 but probably i will continue with directshowsource. Thanks for the help!

[Guest]

Just make sure it's not just the first few frames that are corrupted, as that can happen for other reasons. If you see these in the middle of the stream, then you know you have the issue.

[phate89]

Just make sure it's not just the first few frames that are corrupted, as that can happen for other reasons. If you see these in the middle of the stream, then you know you have the issue.

It actually happens on the frames that DGcavcsource detects as Fields (TFF) so it's exactly that the problem