need to deinterlace with DVB-SAT recordings

[bernd_b]

This is a beginners question which may could be solved by reading other threads, but I wasn't successfull with this, there is too much information.

So if you could gave me links or comments to the following question:

Is it useful to deinterlace a TV-recording made with a DVB-Sat-Card while frameserving with avisynth to TMPGenc to make a vcd/ svcd stream in the ayisynth script itself?


I found the following statements studying several threads in this forum:


1. TV Recording is always interlaced. So you need to deinterlace it.

2. If you aim is to play the result on TV, deinterlacing makes no sense because on TV it's gonna be presented interlaced again (because the TV can only play in "interlaced-mode". If you aim is to play your movie on PC, you need to deintelace or let the deinterlacing be done by your player.

3. If you encode to mpeg1 deinterlace is needed because mpeg1 doesn't support interlaced video, if you encode to mpgeg2 you can leave the whole process interlace because mpeg2 supports interlaced encoding.

4. If you use filter like resizing (Bicubic etc) or noise-reduction you get better quality when deinterlacing first.

:confused: :confused: :confused:
Still confusing for me. Does this mean, you don't need to use a deinterlace filter in the script but you can improve quality when doing so?

P.S: I live in PAL-Land (Germany)

[kassandro]

Normally I don't have the time to answer questions of beginner's, but as I have done more than 1000 dvb-sat recordings, I' ll make an exception this time.
Originally posted by bernd_b
Is it useful to deinterlace a TV-recording made with a DVB-Sat-Card while frameserving with avisynth to TMPGenc to make a vcd/ svcd stream in the ayisynth script itself?

Only if the source is interlaced.


1. TV Recording is always interlaced. So you need to deinterlace it.

No! However, all broadcasts are encoded as if the source were interlaced, i.e. the two fields are encoded separately. In general
cinema films are always progressive. However, there is one caveat. German tv provider are doing a lot of stupid things. Besides switching all the time between mono and stereo, they also often are unable to correctly master photographic film, which results in combs even for progressive source. On anime videos you often find the worst kind of damage for progressive film: field blending.
You can determine, what is going on, by stepping through the clip in vdub with a full frame rate deinterlacer, like avs builtin filter bob (somebody should write a tutorial for this diagnostic process).


2. If you aim is to play the result on TV, deinterlacing makes no sense because on TV it's gonna be presented interlaced again (because the TV can only play in "interlaced-mode". If you aim is to play your movie on PC, you need to deintelace or let the deinterlacing be done by your player.

This is correct. However, then in your mpeg2 encoder, you must encode with the interlace source option turned on. On the other hand, if the source is truely progressive, then you should not encode with interlace turned on, because progressive encoding is much more efficient if the source is progressive.


3. If you encode to mpeg1 deinterlace is needed because mpeg1 doesn't support interlaced video, if you encode to mpgeg2 you can leave the whole process interlace because mpeg2 supports interlaced encoding.

Correct, but again progressive source should not be encoded with interlace turned on.


4. If you use filter like resizing (Bicubic etc) or noise-reduction you get better quality when deinterlacing first.

deinterlacing first is the simplest solution, but if you encode for tv, you may split the fields, resize them separately and weave them together again. Never resize non-progressive input directly!


:confused: :confused: :confused:
Still confusing for me. Does this mean, you don't need to use a deinterlace filter in the script but you can improve quality when doing so?
I think that the confusion should be gone now.

[minolta]

I think kassondro answered your question, but as it concerns TMPGenc...

First off, I assume you can tell the difference between progressive and interlaced, but anyway:

VCD
-------------
This is simple. Height is always 288 and frame rate is fixed at 25fps. So regardless of source type (progressive, interlaced, or bad mixture), the most common and fastest solution is:

SeparateFields().SelectEven().LanczosResize(352, 288)

If your source is progressive (ie. movies) you 'may' get a sharper picture by simply:

LanczosResize(352, 288)

If your source is interlaced (ie. sports, news) you 'may' get a sharper picture by:

YourFavoriteDeinterlacer().LanczosResize(352, 288)

Each has a potential tradeoff, so test for yourself...


SVCD
-------------
You can encode SVCD as progressive or interlaced (TMPGenc will know source type, usually). If your source is interlace, allow TMPGenc to encode it as interlaced. If it is progresive, TMPGenc encodes as progressive (duh!). If your source is a mixture of both as kassandro described, you can try to fix it (possible painful process), deinterlace it to progresive (might lose quality), or just encode as interlaced. Its okay to encode as interlaced, since your tv has interlaced output, and your pc player (windvd, powerdvd, etc.) should deinterlace mpeg-2 during playback.


Know your source, know VCD, know SVCD, and no problem...
-Minolta

[bernd_b]

thanks for your answers.

Know your source seems to be the real problem.

The SeparateFields method for instance seems to work well with cimema material being broadcast.

A part from DS9 encoded with this filter gave sharp picture, but the movements shuttered.

Well, something to make more experiments with... :)

[Didée]

Originally posted by bernd_b
A part from DS9 encoded with this filter gave sharp picture, but the movements shuttered.
DS9, as well as all other Star Trek stuff (except ENT season 1) is field-blended PAL. For this kind of mistreated sources, a harassed soul once had developed the Restore24 script. (original thread (http://forum.doom9.org/showthread.php?s=&threadid=61792&highlight=Restore24), and latest official version (http://forum.doom9.org/showthread.php?s=&threadid=75432).

This is your best chance to get a clean output out of this Paramount stuff.

- Didée


edit: linguistical