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Old 26th September 2005, 11:33   #1  |  Link
amango
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Correct Aspect-Ratio in x264?

I used XVID all the time to encode PAL DVB-streams - now I want to test x264.

Most streams I encode are in 720x576. In XVID I selected the 4:3-PAL setting for the Aspect-Ratio, so the video will be stretched correctly during playback.

In x264 I have the option "Sample AR".

I would like to know what settings I need to type in for correct 4:3-PAL and 16:9-PAL in x264.
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Old 26th September 2005, 11:37   #2  |  Link
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4:3 PAL = 12:11
16:9 PAL = 16:11

If you use these settings you are doing it the same way in x264 and XviD.
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Old 26th September 2005, 11:39   #3  |  Link
amango
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Thank you!
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Old 26th September 2005, 11:53   #4  |  Link
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Or......

PAL 4:3 DAR = 16:15
PAL 16:9 DAR = 64:45

NTSC 4:3 DAR = 8:9
NTSC 16:9 DAR = 32:27

EDIT: In February 2006 I conceived a tool called ARS Calculator to help people work out Aspect Ratio Signalling (ARS) ratios (ie: PAR, SAR, DAR) for use with encoders such x264 and XviD


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Last edited by SeeMoreDigital; 2nd October 2006 at 16:10.
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Old 26th September 2005, 12:13   #5  |  Link
amango
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What's the formula...?

Sometimes I have DVB-streams in 480x576 or 704x576 PAL. Can I also set the correct AR in x264 for this resolutions...?
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Old 26th September 2005, 12:51   #6  |  Link
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Personally speaking I prefer to use the (4:3 or) 16:9 DAR calculations because they will always output an (4:3 or) 16:9 shaped image, regardless of the sources pixel size/ratio.


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Old 26th September 2005, 16:52   #7  |  Link
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Quote:
Originally Posted by amango
What's the formula...?

Sometimes I have DVB-streams in 480x576 or 704x576 PAL. Can I also set the correct AR in x264 for this resolutions...?
PAR (or SAR) = DAR*height/width
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Old 29th September 2005, 14:34   #8  |  Link
fatxy
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which player besides vlc can handle that properly?

tested zoomplayer with ffdshow without success

Last edited by fatxy; 29th September 2005 at 14:36.
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Old 29th September 2005, 21:48   #9  |  Link
Inc
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Quote:
Originally Posted by stephanV
PAR (or SAR) = DAR*height/width
In case of respecting the actual "real" DAR of your source then it makes sense.

Good Example a 52.000µs capture:
DAR = 1,3333 * 576 / 702 = almost 1,094:1 = PAR 128:117
Here a 702x576 is truely DAR 4:3 @ PAR 1,094

Bad example, a fullscreen 720x576 DVD as source:
DAR = 1,3333 * 576/720 = 1,06664 = the common error of generic par happens here

720 * (128/117) / 576 = DAR 1,3675:1 equals not 4:3 (1,3333)

DAR = 1,3675 * 576 / 720 = PAR 1,094:1 = ok





Quote:
480x576 autozoom to 768x576

or somethin like

480x576 encode to 640x480 or even 768x576


480x576 px sources do have 53,3333us (same as 720x576).
768x576 do have 52,0000us

53,3333/52,0000 = 1,02564 <--- our diff. factor!

So do resize 480 x 576 to 768*(1,02564) x 576 = 788x576

or do crop 480 x 576 to 480/1,02564 x 576 = 468x576 and resize to 768x576



If you do respect these your eyes when watching mpeg4s via HTPC will kiss you.

Last edited by Inc; 29th September 2005 at 21:54.
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Old 29th September 2005, 14:39   #10  |  Link
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enable overlay mixer in ffdshow
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Old 29th September 2005, 15:08   #11  |  Link
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thanks i changed the output to overlay mixer for both ffdshow and zplayer
i only get a black screen :/
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Old 29th September 2005, 15:17   #12  |  Link
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Added more info on SAR in the daily builds FAQs.
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Old 29th September 2005, 15:37   #13  |  Link
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Quote:
Originally Posted by fatxy
thanks i changed the output to overlay mixer for both ffdshow and zplayer
i only get a black screen :/
Thats sucks... have you tried MPC?
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Old 29th September 2005, 17:21   #14  |  Link
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Quote:
Originally Posted by fatxy
thanks i changed the output to overlay mixer for both ffdshow and zplayer
i only get a black screen :/
overlay mixer and ffdshow work perfect in zplayer. You can also take Video Mixing Renderer 7 and ffdshow. Looks great
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Old 29th September 2005, 18:46   #15  |  Link
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Just in-case anybody needs to know, here are the FFdshow "overlay settings" I use in-conjunction with MediaPlayer Classic: -



Encodes with AR signalling in AVI, MP4, MKV and OGM work perfectly....


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Old 29th September 2005, 21:13   #16  |  Link
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ok thanks a lot

zplayer vmr and ffdshow overlay mixer works (thought i have to use it for both), not as smooth as vcl but its workin (i have to click on fit source one time)

besides i dont really know what to do with those crappy 480x576 streams

480x576 autozoom to 768x576

or somethin like

480x576 encode to 640x480 or even 768x576

Last edited by fatxy; 29th September 2005 at 21:27.
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Old 19th January 2006, 17:12   #17  |  Link
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Full TV PAL is 768x576 @ 52.000µs @ 14,7692307Mhz (= quadra pixels)
ITU samplingrate is 13,5 Mhz (= squarepixels)

14,7692307/13,5 = 1,094017 = TV PAR @ 13.5Mhz used by a SAP

or ...
52.000µs * 13.5Mhz = 702 active pixels at square pixels
52.000µs * 14,7692307Mhz = 768 active pixels at quadra pixels

768/702 equals 128/117 equals 1,094017


Last edited by Inc; 19th January 2006 at 17:15.
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Old 19th January 2006, 18:26   #18  |  Link
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That's fine for anamorphic encodes with pixel frame width of 702....

However, if you want to generate spec PAL video files with a target aspect ratio of 4:3 based on a pixel frame width of 720, I would recommend you use the following calculation: -

768/720 = Lowest fraction = 16/15 (Decimal = 1.094017)


However, if you want to generate spec PAL video files with a target aspect ratio of 16:9 based on a pixel frame width of 720, I would recommend you use the following calculation: -

1024/720 = Lowest fraction = 64/45 (Decimal = 1.422222)


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Old 19th January 2006, 18:55   #19  |  Link
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What would you suggest for NTSC Analogue captures with a width of 720 or 704 pixels?

For example, I have an analogue capture at 720x480 which I crop to 720x360 to remove letterboxing, the resize back to 720x480 anamorphic.

Using the cropped resolution:
16.9 = 1.7777 -> (1.7777x360)/720 = ~640/720 = 0.888

640/720 equals 8/9 equals 0.8888

This doesn't look right.

EDIT: This of course assumes the original pixel width is actually 720 and not at all taking into account things like what my ATI AIW 8500's capture window is etc etc.

Last edited by Piper; 19th January 2006 at 19:04.
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Old 19th January 2006, 19:45   #20  |  Link
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Quote:
Originally Posted by Piper
640/720 equals 8/9 equals 0.8888

This doesn't look right.
I think you'll find it does though


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