encoding PAL/DV to 50fps progressive avc/H264 material

Bug report and feature request
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How many images per second does PAL video contain?

Poll ended at Sun May 04, 2008 4:28 pm

25
2
67%
50
1
33%
do you mean frames or fields? (i said... images)
0
No votes
images? aren't movies made of stardust?
0
No votes
 
Total votes: 3

miwubai
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encoding PAL/DV to 50fps progressive avc/H264 material

Post by miwubai » Mon Apr 14, 2008 4:28 pm

Ok H264 is definately the best codec around now, and finally i want to get around storing my almost one hundred DV tapes into a nice looking and smallest possible format without losing quality.

WHAT are all Pinnacle Ulead etcetc, expensive software makers thinking that they just ALWAYS throw away half the frames and make PAL 25fps ?
PAL is NOT 25imigas per second, but 50 images per second
right call it frames, fields whetever you like, it's 50/s ok?!

so now WHO is finally coming with an aplication to code to 50p? microsoft? with their bummed out *weave* method WMM2 uses, making all wmv look blurred while the codec is perfectly able to produce fine looking quality 50p..

*sigh* just spend another hours with avisynth etc etc sofware exporting and importing one to the other.

Yes, i know it's possible using 5 steps, maybe even 3...
but why not *one* step, and indroduce simple reliable (mediacoder often wrong with timecodes on mpg) start and stop settings and ability to join files into one video.....?

*maybe* even some simple drag and drop editing of sequences???


let me know if 10 years of development in video applications there is ONE that can code a VOB or DV avi file to 50 fps progressive AVC/H264 video directly. Please.... Mike, China
After over a decade of PAL DV/DVD being introduced WHY has no-one introduced a onestop-onestep way of encoding to 50fps progressive WMV/rmv/Divx/H264 so you can watch and store the movies on HDD/monitor without throwing away half the framerate?

istvan01
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Post by istvan01 » Mon Apr 14, 2008 6:40 pm

Hi,

it is not a good Question.

progressiv PAL contains 25 frames (full pictures), interlaced contains 50i (50 half pictures(odd and even lines).

With deinterlacing is possible to make 25p from 50i. I do not however even heard, if it would be possible to make 50p from 50i. There is no enough information in the footage to make it.

Regards,

I.

miwubai
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well how do you explain this?

Post by miwubai » Mon Apr 21, 2008 5:02 pm

I recorded my hand waving left and right in one second
with a PAL DV camcorder. connected firewire to computer, capture the hand waving to uncompressed avi file
then play with mediaplayer classic, with ffdshow installed, set on DGbob deinterlace. this way you will be able to play the video FIELD by FIELD with mediaplayer classics 'one frame forward' button. instead of 25, you will find 50 still frames per second and
IN EVERY IMAGE THE HAND IS IN A DIFFERET POSITION.

You can do the same playing DVD PAL VOB files of TV shows, or other content that is originally interlaced.

Yes, for Movies wich are ALWAYS 24 frames per second (chemical film material, almost unlimited resolution) when converted to PAL will give 25 progressive frames per second (movie plays slightly faster on PAL then in the theater.)

and so even these VOB files will say they are interlaced, every 2 consecutive fields are actually copies of one and the same film frame.

If you want i will send you some samples. also of 50fps divx files i made of bob-deinterlaced DV material. you will see even without installing the dgbob filter or ffdshow that in mediaplayer classic you can step forward 50 times in one second and find every image is a different one!

the fact that PAL records 50 images per second in 720 x 288 resolution and that those 288 lines are alternately even and uneven lines of a 576 vertical resolution frame, ONLY adds up to 25 fps progressive movie, when every 2 conecutive frames would be equal, (as in a movie that is originally not interlaced) OR when nothing is moving (!!)
( 'something' is almost always moving in a movie, thats why it's called a movie, duh)

Dr Divx is one of the few programs that uses 'smart' de-interlacing. It looks for every 2 consecutive fields if they are the same (like in still images or the credits IF they are not scrolling up) and if they are the same will use BOTH fields to reconstruct an 720 x 576 image.

When -SOMETHING- is moving it will DISCARD the second field, (throwing away a position of the hand that is NOT showed in the previous or next frame, making the movie less smooth.) and it intepolates between the lines that are known, to fill in those lines that are left blank.

those frames are fields of original resolution of only one field (720 x 288) but every line is doubled by interpolating colors, much like you would increase an original picture of low resolution to a higher one. (and everyone knows that will NOT increase the detail in a picture, right?)

ok sorry for giving such a long lecture, but i really have spend years researching the interlaced dilemma, and the truth is: there is no perfect way of reconstructing 50p from 50i but, making it 25p means you are trowing away half the frame rate. much like changing it from 25 to 12.5.

it is easy to see the increased chopyness.

NB: VLC player also has built in capability to display interlaced either:

-deinterlacing 'none' = 'weaved' 25 fps are displayed with the 2 fields weaved together, making every step contain 2 hands.

-deinterlacing 'interpolate' = half of the hands are discarded the other half filled in the blank lines to show one hand per frame, 25 frames per second.

-deinterlacing 'bob' = none of the hands are discarded, 50 hands per second are shown, making twice as smooth motion, the missing lines are filed in by interpolating.

Why are there missing lines? = because PAL was invented for display on TV's working with electron rays on fluescent tubes, and on those tubes you do not notice the 'missing lines as the other lines are still afterglowing from 1/50second earlier.

why does interlaced not play well on computermonitors? the monitors are so fast that you would actually notice the missing lines if they were displayed 'as is' = 50 times per second, interlaced with blank lines.

NB: good sofware DVD players (powerDVD etc) actually do show the 50 fps framerate and they do bob-deinterlace, but like mediaplayer classic without ffdshow installed, if doing step by step, by default it can only step 2 fields at a time and you have to have good eyes to distinguish 50fps and 25fps without setting it to superslow or step by step.

hope to have filled in the reasons why i do not agree with you.

the way you put it:
if i'd make one 720x576 picture of me, and one 360x288 picture of you, yours would be only HALF a picture, and not complete?
i'd have to make 2 or 4 pictures of you to have a 'whole' picture?
because i made 'half' pictures of you?

no of couse not!

there is no such thing as 'half' a picture. there are just high resolution pictures or low resolution pictures. PAL is 50fps 720x288 fields.
the fact that PAL uses alternate even and uneven lines to make those fields ONLY makes double the resolution/half the framerate if every 2 consecutive fields are identical !

so to make that one high resolution foto of you, you'd have to stand pretty still and then hope the 2 pictures i made with a 1/50 second difference are the same, and then weave them together to get one 720x576 picture out of 2 720x288 ones made with the camera moved half a vertical line up.

with camcorders and making footage by hand two consecutive frames are NEVER identical, and making 25p from 50i always means you are discarding half framerate and half the the bruto data before even encoding it.

M.

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Re: encoding PAL/DV to 50fps progressive avc/H264 material

Post by cliveontoast » Sat Aug 20, 2022 6:35 am

I found this question when I was also trying to shrink all my huffyuv VHS tapes to something more modern.

ffmpeg and x264 happily encode to a 50 progressive frames per second, using yadif 2x to interpolate the missing lines.

In my case, I had a 25p huffyuv avi source. Inside it, had the 50 fields stored as top first.

https://video.stackexchange.com/a/35611/39113 Option 3. x264 and Option 4. x265 both create 50p output looking very smooth and when converted to yuv420, castable to chromecasts.

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