Deinterlacing automatically done?

[guju]

I'm a bit confused about ADM converting MPG2 interlaced movies to AVC (progressive).

Is there done some "implicit"/ "automatic" deinterlacing (When decoding MPG2 or when encoding AVC)?
Looks like to me.

Or do I always have to add explicitely a deinterlace filter for that?

[guju]

Having a closer look I find all this quite puzzling:

Movies with property interlaced aren't all the same:
Some have a pronounced combing effect;
but most have not but look like de-interlaced/ smeared,
some of them look like having half frame rate with each
second frame kind of improving its predecessor.

ADM shows true interlaced movie only in filter preview,
otherwise it shows them kind of deinterlaced.

I wouldn't care about this confusion, if it wouldn't be important
for filtering and for transcoding.

I hope someone may bring some clearance...

[eumagga0x2a]

No, there is no automatic deinterlacing. If the source is interlaced, you have the choice of either deinterlacing it by adding a deinterlacing filter usually as the very first filter in the filter chain, use deinterlacer available for post-processing (implies not using hw accelerated decoders) or not performing any filtering at all but instead telling x264 to use a (non-progressive) scan method compatible with interlaced input.

Some videos are created from progressive material like movies so that both fields represent one and the same moment in time. Only in this case interlacing can be ignored.

[guju]

Thank you for your profound info - once again

However it was your last sentence that kept me from heart attack.
(That would have been some dozens movies mistreated by me).

Obviously nowadays there are not too many true interlaced movies around
(The bonus material of DVD/BD sometimes is interlaced).

All those movies you mentioned are a problem however:
They are "false-interlaced" (wrong labelled).
If you take the meta data for real you will ruin the
movies when deinterlacing them.

Also the other way round:
There are many videos labelled progressive
that obviously are un-deinterlaced interlaced movies ("false-progressive").
If you would know they are actually interlaced you may have the chance
to repair that if the compression etc. is not too strong.

So it's important to know the true scan type of a video.

To get that you can either laboriously check visually.
(I already mentioned ADM by default seems to have a "deinterlaced" view.
You see interlaced truth only when manually switching the zoom view.
And the latter is not saved, you always have to switch again.
Also for me "1" und "2" shows the frame in same size, with small
content differences...
Something should be done in ADM about this)

The other option to reveil scan type is to ask an algorithm
(I know only of ffmpeg's idet).
https://ffmpeg.org/ffmpeg-filters.html#idet
Using it is easy enough but maybe a menu entry in ADM...?

[eumagga0x2a]

Truly interlaced Videos, re-encoded without deinterlacing as progressive, are irreversibly ruined.

I wouldn't rely on automatic detection, don't forget that some videos switch between interlaced and progressive mode on the fly.

Avidemux needs zoom mode with scrollbars.

[guju]

...
Avidemux needs zoom mode with scrollbars.

Sorry, there must be some misunderstanding.
I was trying to say that interlaced movies in the main window are displayed kind of "non-interlaced"
@ zoom-mode "start", 0, 3 and 4.
Only at 1 and 2 interlacing is shown. But then both show the same size, with the frame stretched to the borders (i.e. non-proportional).
All this with OpenGL.
==> Bug!
When setting DXVA2 everything is correct - only with big zoom scrollbars are missing.

[guju]

Truly interlaced Videos, re-encoded without deinterlacing as progressive, are irreversibly ruined.

I just made a test.
If the "false-progressive" movie isn't compressed too much, ffmpeg's idet filter is capable of identifying it as interlaced, as well as e.g. ffmpeg's nnedi deinterlace filter is capable of repairing it quite good.

I wouldn't rely on automatic detection, don't forget that some videos switch between interlaced and progressive mode on the fly.

I've to contradict to this too. idet can detect scan mode framewise, as well as nnedi has an option to deinterlace only the frames identified as interlaced.