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magnatique
20th October 2006, 15:35
ok, I've read as much as I could to make it out, but am kinda lost, as most of the indications are for HDTV, and not HD movie files from an hd camera.

what I'm wondering is if the initial format captured from the camera is an avi file of 1440x1080, what ratio would I be using?

is the hd dv signal already 1:1 so I'd just use the same ratio to display on a computer?

IE if I want it to have 720 of width, then it'd be 540 of height?

magnatique
20th October 2006, 16:36
another thing I clearly do not understand is, while it says 1440x1080, which is a 4:3 ratio, the image itself is on a 16:9 elongated display...

so for what reason would the original be off a 4:3 ratio, but displayed at 16:9... why not 16:9 altogether ?

thanks a lot guys, I appreciate any help in trying to make my brain a little thicker ;)

smok3
20th October 2006, 18:03
just some notes (i could be wrong):

1. there is no hd dv (maybe hdv?)
2. 1440x1080 is 16:9 anamorphic - 1.333 pixel aspect ratio (upsized to 1:1 would be 1920x1080)
3. if you want to go to pal SD resolution, resize to 720x576, again 16:9 anamorphic

magnatique
20th October 2006, 18:56
hdv is right, typoed that ;)

but here is the thing, which I do not understand...

how is 1440x1080 16:9, when that's a 4:3 ratio?

so, if I get this straight...

the stream contains data for 1440x1080, but if recorded to be a 16:9 display, when viewed at 1440x1080, it'd be distorted... so when playing it on a tv , the tv would perform the change to display at 16:9..

but, in the case of a computer screen, where we are at 1:1 ratio displayed, what we would need to do to get a proper display is to upscale to 1920x1080... or downscale to say 960x540 for example...

is that thinking right?

SeeMoreDigital
20th October 2006, 20:20
but here is the thing, which I do not understand...

how is 1440x1080 16:9, when that's a 4:3 ratio?It's because the pixels are given a "rectangular" shape, with the aid of ARS (Aspect Ratio Signalling) instead of being square ;)

By-the-way, the same technique is used for both 4:3 and 16:9 DVD images, DVB-T/S/C broadcasts, DV camcorders images and even good 'ol VCD images.

smok3
21st October 2006, 02:18
well, quoting cineform guy:
"Both 1440x1080 and 1920x1080 are standard distribution formats for MPEG2, VC-1, WMV-9"

full artcle is here:
http://cineform.blogspot.com/2006/08/hvx200-resolution-options.html

yes in case of 1440x1080 you need to upscale, but that doesnt necesarily mean to upscale prior to encoding, with proper flags you could do it at playback time..., however i did 1:1 encodes of the 1280x720p material (where original resolution was 960x720) ..., so well i guess you will have to decide.

p.s. there is no 4:3 plans in new Hd era afaik.

Blue_MiSfit
23rd October 2006, 00:42
yeah thats how dvcprohd works too, it stores internally at 960x720, and upsamples on playback to 1280x720, or for 1080, it does 1280x1080 internally and 1920x1080 on playback.

HD is just so fracking big... you gotta make compromises somewhere... I'm no fan of subsampling though.

~MiSfit

magnatique
31st October 2006, 15:47
thanks a lot guys, this helps a lot :D