Bluray to DVD - does this look right

[Carpo]

Got bored so decided to see if i could backup a 1080p bluray to dvd, and author a disk.

here is the avs script, nice and simple, im just not sure on the resize, after a bit of reading a lot of places said to use 720x432, to keep it 16:9.

LoadPlugin("D:\dgindexnv\DGDecodeNV.dll")
DGSource("D:\DISC_RIPS\the.dark.knight.dgi",fieldop=0)
#deinterlace
crop( 0, 142, 0, -142)

Spline36Resize(720,432) # Spline36 (Neutral)
#denoise

Yet other places have said to use 1024x576 and others 768x432, what would others more knowledgeable in such things suggest?

So im a little unsure, yes i know there is better things i could be doing with a Saturday ;)

[Lyris]

Assuming the disc you want to make is NTSC, the final frame output size has to be 720x480. Or for PAL, 720x576.

1024x576 (PAL widescreen square pixels) and 768x432 (not sure what that is) aren't valid frame sizes in DVD-Video.

[Carpo]

Assuming the disc you want to make is NTSC, the final frame output size has to be 720x480. Or for PAL, 720x576.

1024x576 (PAL widescreen square pixels) and 768x432 (not sure what that is) aren't valid frame sizes in DVD-Video.

Seeing as im uk based i would think it would be best to stick with PAL, Although for some reason tsmuxer is saying the frame rate of the bluray is 23.973, so guess i may have to use NTSC as HCenc is moaning at me to use 3:2 pulldown to make it dvd compliant.

Guess some trial and error is required :-)

[Lyris]

It depends what you find the lesser of two evils. NTSC's lower resolution or PAL's incorrect speed?

Going to NTSC is probably easier because you don't have to time stretch the audio.

[Carpo]

yes i went with NTSC on the test seems to play fine :-)

[TheSkiller]

If you crop the 1920x1080 source picture to 1920x796 and then resize that straight to 720x480 you end up with egg-heads.


The width for a standards-compliant DVD does not have to be 720 (for both NTSC and PAL), it can be also 704 and I would recommend to use 704 to avoid the dreaded ITU vs non-ITU issue.

16:9 NTSC has a Pixel Aspect Ratio of 5760/4739.

704 / (1920/796) * (5760/4739) ≈ 354,7

Since we need a number that is even after being divided by 2 - because we need to add top/bottom borders to a video that is probably YV12 - we round it to 356.

Spline36Resize(704,356)
AddBorders(0,62,0,62)


However, the easier (and even more precise) way would be not to crop in the first place and resize the 1920x1080 source picture straight to 704x480. :rolleyes:

[Carpo]

Thanks for the info :-)

[poisondeathray]

when going HD to SD you can add

colormatrix(mode="rec709->rec.601", clamp=0)

[Carpo]

thanks, will add that to avs :-)

[poisondeathray]

Sorry that's a typo (missing period) should be

colormatrix(mode="rec.709->rec.601", clamp=0)

[Biggiesized]

If you crop the 1920x1080 source picture to 1920x796 and then resize that straight to 720x480 you end up with egg-heads.


The width for a standards-compliant DVD does not have to be 720 (for both NTSC and PAL), it can be also 704 and I would recommend to use 704 to avoid the dreaded ITU vs non-ITU issue.

16:9 NTSC has a Pixel Aspect Ratio of 5760/4739.

704 / (1920/796) * (5760/4739) ≈ 354,7

Since we need a number that is even after being divided by 2 - because we need to add top/bottom borders to a video that is probably YV12 - we round it to 356.

Spline36Resize(704,356)
AddBorders(0,62,0,62)


However, the easier (and even more precise) way would be not to crop in the first place and resize the 1920x1080 source picture straight to 704x480. :rolleyes:

Indeed. Don't confuse him with the pixel aspect ratio (however technically correct it may be). It's easier just to tell him 40/33. It's the same whether you use 704 or 720 (plus 16 pixels of black padding).

[Carpo]

Indeed. Don't confuse him with the pixel aspect ratio (however correct it may be). It's easier just to tell him 40/33. It's the same whether you use 704 or 720 (plus 16 pixels of black padding).

Indeed don't confuse me ;)

Happy to say that it went well and plays fine, just a bit hit and miss on calculating the bitrate, final size was 4.31GB, which is respectable :)

Thanks to all that helped :)

[Richard1485]

when going HD to SD you can add

colormatrix(mode="rec.709->rec.601", clamp=0)

What does clamp=0 do? I have always used just colormatrix(mode="rec.709->rec.601") Is this wrong?

[poisondeathray]

What does clamp=0 do? I have always used just colormatrix(mode="rec.709->rec.601") Is this wrong?


it's not necessarily "wrong" , it just clips the data to "legal" levels. But specs were set Y'16-235 and CbCr 16-240 to allow for undershoot and overshoot.

from the docs:


Clamp

Specifies whether pre/post clipping with limiter to 16-235/16-240 should be used. Possible settings:

0 - no clipping
1 - pre clipping (clip input to ColorMatrix)
2 - post clipping (clip output from ColorMatrix)
3 - pre and post clipping

3 is what previous (v1.x) versions of ColorMatrix used.




note this is clipping (ie. values are cut off), not clamping (where values are there, just "squished")

[Richard1485]

Ah, so colormatrix clips by default to avoid overshoot and undershoot, but as the specs were designed to accomodate that anyway one does not really need to do so.

note this is clipping (ie. values are cut off), not clamping (where values are there, just "squished")

The parameter is called clamp whereas in fact it clips, so it's essentially a misnomer. Thanks for the reply. : )

[Richard1485]

colormatrix(mode="rec.709->rec.601", clamp=0)

I've just tried the clamp parameter for the first time. I receive an error message:

Script error: the named argument "clamp" to colormatrix had the wrong type

EDIT: It's funny, with this HD source the reds look the way they usually do with Rec.609 before the conversion, and the reds look the way they usually do with Rec.709 after the conversion.

[Carpo]

LoadPlugin("D:\dgdecnv2038\DGDecodeNV.dll")
DGSource("D:\DISC_RIPS\the.dark.knight.dgi",fieldop=0)
#deinterlace
#crop
colormatrix(mode="rec.709->rec.601", clamp=0)
Spline36Resize(704,480) # Spline36 (Neutral)
#denoise

Is what i use and it works fine for me, i use the dll from here - http://bengal.missouri.edu/~kes25c/ColorMatrixv25.zip

[Richard1485]

Thanks, Carpo! It seems I had an older version of ColorMatrix. I still think the colors look the wrong way round though lol.

EDIT: it's not a BD source, so I suppose this is slightly off topic. Problem solved now anyway...