Blu-Ray - 50Hz vs 60Hz

Snowdon-Goat

Standard Member
Het guys

Can someone explain to me why normal DVDs run at 50Hz on my PS3, but the default frequency for Blu-Ray discs is 60Hz?

I realise that 24Hz is the optimal setting for films on Blu-Ray discs (which I normally have selected), but as a point of interest can someone explain to me why 60Hz looks so much more juddery than 50Hz – and why the PS3 (or any other player?) outputs Blu-Ray at the more jerky 60Hz instead of the seemingly smoother 50Hz of regular DVDs?
 

kingfats

Distinguished Member
Het guys

Can someone explain to me why normal DVDs run at 50Hz on my PS3, but the default frequency for Blu-Ray discs is 60Hz?

I realise that 24Hz is the optimal setting for films on Blu-Ray discs (which I normally have selected), but as a point of interest can someone explain to me why 60Hz looks so much more juddery than 50Hz – and why the PS3 (or any other player?) outputs Blu-Ray at the more jerky 60Hz instead of the seemingly smoother 50Hz of regular DVDs?
Hi Snowdon-Goat. :)
BD DVD will use the "default" NTSC frequency 60Hz if your TV cannot accept and display 24fps correctly :) Film BD DVD was originally shot at 24fps.
60Hz will give you judder as it's an uneven framerate :( you have to go like this > 24Hz > 72Hz or another example > 50Hz > 100Hz,it always has to be multitudes of to get smooth playback/framerate. :smashin:
PAL DVD shot in 576p25, authored at 576i50 on the disk,so will display on a PAL TV with no judder. (60 into 50,does not fit............judder)
NTSC TV is 60Hz and PAL TV is 50Hz.
All the best.
 

Snowdon-Goat

Standard Member
Thanks Fats,

So it's basically to do with the fact that regular DVDs are authored at 25fps but Blu-Rays at 24fps.

My TV will do 24Hz (though have some Samsung hum bar problems) but plenty of TVs won't. I can't really understand why they didn't just 'author' Blu-Rays at 25fps like they did regular DVDs - then there wouldn't be all this fuss people are having with 24Hz compatability. Afterall 50Hz movies look just as smooth as 24Hz.

Also, you say the TV will force a 60Hz (NTSC) frequency on to Blu-Ray playback if it can't display 24Hz (or multiples of), but onthe PS3 you can disable 24Hz mode - so surely it's the player that is outputting 60Hz then (rather than the TV converting 24Hz to 60Hz)? If so, why does it choose to output 60Hz rather than 50Hz (which is EU standard, I think)?

Also, would a 24Hz signal converted to 50Hz look any better than a 24Hz signal converted to 60Hz? I know 24 into 50 doesn't go - but it goes better than 24 into 60.

Cheers
 

kingfats

Distinguished Member
Thanks Fats,

So it's basically to do with the fact that regular DVDs are authored at 25fps but Blu-Rays at 24fps.

My TV will do 24Hz (though have some Samsung hum bar problems) but plenty of TVs won't. I can't really understand why they didn't just 'author' Blu-Rays at 25fps like they did regular DVDs - then there wouldn't be all this fuss people are having with 24Hz compatability. Afterall 50Hz movies look just as smooth as 24Hz.

Also, you say the TV will force a 60Hz (NTSC) frequency on to Blu-Ray playback if it can't display 24Hz (or multiples of), but onthe PS3 you can disable 24Hz mode - so surely it's the player that is outputting 60Hz then (rather than the TV converting 24Hz to 60Hz)? If so, why does it choose to output 60Hz rather than 50Hz (which is EU standard, I think)?

Also, would a 24Hz signal converted to 50Hz look any better than a 24Hz signal converted to 60Hz? I know 24 into 50 doesn't go - but it goes better than 24 into 60.

Cheers
Hi Snowdon-Goat. :)
All film is shot @ 24fps,for PAL DVD is sped up to 25fps :) so it will work on your TV.Americans have no speed up (audio) with DVD,but then they have judder :( 24fps > 60Hz...........again to work on their TV ( 60Hz)
There's loads here on the 24Hz >50Hz issue and the problems it will bring here.
You say your TV does 24p,then if it does this properly,you will have no judder on Blu-ray playback........set PS3 to 1080p/24,on or auto.

Cheers.
 

Snowdon-Goat

Standard Member
Like I say, I use 24Hz, it's more just out of interest I'm asking (and incase, since I have some 24Hz issues on my TV, there was a way to run Blu-Ray at 50Hz and recreate the results of DVD at 50Hz - which from what you say clearly there isn't).

Guess the DVD conversion to 25fps from 24fps meant audio (and the whole film) ran a little faster on DVDs (think I've noticed this on some songs at the end of films).

Will check out the thread you gave - and if I have further questions might bug you agian if that's okay?

Thanks for all your help so far!
 

kingfats

Distinguished Member
Will check out the thread you gave - and if I have further questions might bug you agian if that's okay?

Thanks for all your help so far!
Don't worry about asking questions :thumbsup: that's what the forums here for ;)
and if i've got anything wrong :) someone will post and correct. :D
 

bsuttie

Novice Member
All film is shot @ 24fps
Oh no it isn't - whilst almost all feature films for International distribution will be, there's a lot of film shot in Europe at 25fps.

We do need better support for 25 fps, particularly as more TV series and independent films will start appearing on Blu Ray and I for one would like to see them at their original frame rate.

regards

Brian
 

kingfats

Distinguished Member
Oh no it isn't - whilst almost all feature films for International distribution will be, there's a lot of film shot in Europe at 25fps.

We do need better support for 25 fps, particularly as more TV series and independent films will start appearing on Blu Ray and I for one would like to see them at their original frame rate.

regards

Brian
Hi bsuttie. :)
Ok,cheers mate :smashin: i can't see why they couldn't appear on Blu-ray :cool: as the format supports 1080p/25. :smashin:
All the best.
 

Avi

Distinguished Member
Oh no it isn't - whilst almost all feature films for International distribution will be, there's a lot of film shot in Europe at 25fps.

We do need better support for 25 fps, particularly as more TV series and independent films will start appearing on Blu Ray and I for one would like to see them at their original frame rate.

regards

Brian
Does the Blu-ray specification support 1080p/25 or 1080p/50 ? I didn't think it did but I may be wrong.

AVI
 

bsuttie

Novice Member
Does the Blu-ray specification support 1080p/25 or 1080p/50 ?

AVI
My understanding is that 1080 has to be 50i rather than 25p or 50p
720 can be 50p

Of course there's nothing stopping you putting 1080 progressive material in a 50i stream.

regards

Brian
 

Ian_S

Distinguished Member
There's no direct support for 1080p/25 or 30 in the Blu-ray spec. You have to encode as 50i or 60i and *hope* your player will correctly output as progressive, or that if you pass as is on disc to a display or VP, that they do the right thing and correctly stitch it all back together.

An example of such a disc is the Nine Inch Nails BD, which was recorded as 30p, but is presented as 60i on disc.
 

kingfats

Distinguished Member
There's no direct support for 1080p/25 or 30 in the Blu-ray spec. You have to encode as 50i or 60i and *hope* your player will correctly output as progressive, or that if you pass as is on disc to a display or VP, that they do the right thing and correctly stitch it all back together.

An example of such a disc is the Nine Inch Nails BD, which was recorded as 30p, but is presented as 60i on disc.
Hi Ian_S. :)
When you say "no direct support" for 1080p/25 or 30 :) does that mean it can't (due to spec) or it "could" happen in the future?
Cheers,mate.
 

Ian_S

Distinguished Member
Hi Ian_S. :)
When you say "no direct support" for 1080p/25 or 30 :) does that mean it can't (due to spec) or it "could" happen in the future?
Cheers,mate.
Not in spec, so IMO unlikely to ever be in spec. However 50i can deal with UK or European live 1080i footage and if properly de-interlaced European shot 25p too. So, BBC, give us Planet Earth in 50Hz..:smashin:
 

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