TVs & widescreen
category: general [glöplog]
I don't do much safe-area protection for my scene.org dvd captures because I figured out most modern TVs have reasonably small margins and it was well worth the effort to have the full resolution for those who can watch it. (Or who are using their PCs to watch DVDs)
The onus really is on the demomakers already, considering they have also to take a sort of "safe area" into account for video projection at parties.
As for 16:9 16:10 or 4:3, it's much less of a bother to produce in 4:3 first (even if it means black borders) ...
The 16:9 standard I find particularly half baked since it's not even equal to movies' resolutions :(
The onus really is on the demomakers already, considering they have also to take a sort of "safe area" into account for video projection at parties.
As for 16:9 16:10 or 4:3, it's much less of a bother to produce in 4:3 first (even if it means black borders) ...
The 16:9 standard I find particularly half baked since it's not even equal to movies' resolutions :(
kb: thanks for the breakdown. It's always good to have a decent starting guide. Any recommendation on bitrates for decent quality h264 at 1080p? (or is 1080i actually smoother?)
i don't understand the whole safe area story in this context. who ever put the most mindblowing effect in a demo in the tiny top left corner? does it really matter if we can't completely read the "q"'s tail in the equinox greeting on the bottom of the screen?
i only see a point for menus and stuff, and subtitles, neither of which are really common at all in demos. and if they are, it doesn't really matter if they get cut off a tiny little. i can't really cook up a single demo that i'd enjoy less if i'd see only 90% of the screen width and height (especially if i wouldn't know it).
i only see a point for menus and stuff, and subtitles, neither of which are really common at all in demos. and if they are, it doesn't really matter if they get cut off a tiny little. i can't really cook up a single demo that i'd enjoy less if i'd see only 90% of the screen width and height (especially if i wouldn't know it).
if you've got 1080p/60 you've got 60 full frames per second at 1920x1080. 1080i is actually only 30 full frames (60 half frames) per second.
skr: its more relevant to interactive stuff indeed, but nonetheless its nice to properly set up your videomodes on for ex. a console to account for overscan/safe area and such for demos as well
skrebbel: random old prod off the pouet latest added list: http://www.pouet.net/prod.php?which=33975
Scroller right at the bottom of the screen, logo goes right to the top. Running on an amiga without overscan is fine, but scale it to 720x576 for a dvd and on older tvs you won't see the scroller at all I bet, and the top of the logo will disappear. Basically, you ruin the demo. Same thing happens to lots of more recent demos, they often have a logo or something like that right at the screen edge.
Scroller right at the bottom of the screen, logo goes right to the top. Running on an amiga without overscan is fine, but scale it to 720x576 for a dvd and on older tvs you won't see the scroller at all I bet, and the top of the logo will disappear. Basically, you ruin the demo. Same thing happens to lots of more recent demos, they often have a logo or something like that right at the screen edge.
knos: HD has support for at least 24, 25, 30 50 and 60 Hz.
psonice it all comes down to how you captured it. If you capture the demo from analog signal then you don't have to do any safe-area protection:
The full signal (related to (H/n) x 576 where n is 1..2) is in full resolution, 740x576.
Of this full screen, the demo was probably working in the 640x512 window, so already including a safe area.
Now if you used an emulator and captured the directly rendered frames, then you might want to add the safe area borders that were magically removed.
The full signal (related to (H/n) x 576 where n is 1..2) is in full resolution, 740x576.
Of this full screen, the demo was probably working in the 640x512 window, so already including a safe area.
Now if you used an emulator and captured the directly rendered frames, then you might want to add the safe area borders that were magically removed.
And of course I simplified the whole thing for the sake of argument, the amiga resolution might as well have been 320x256, in any case a 4:3 region of the size of the safe area already.
The work of handling this safe-area has already been done so to say by the home computer's manufacturer. When you're producing a DVD then you're doing this job as well.
The work of handling this safe-area has already been done so to say by the home computer's manufacturer. When you're producing a DVD then you're doing this job as well.
knos: yes, that's what I'm getting at, although the amiga demos are a bad example really as they should output at full pal res. I'm only looking at capturing a few older pc demos at the moment (well, h+ to be exact :) and there you have 640x480, with stuff often right at the edges.
As a sidenote (somewhat offtopic):
Amiga and C64 demos (plus all 8/16bit consoles and the PlayStation 1 ;) have another problem when capturing anyway: They don't even output proper PAL.
Interlacing in analog video signals is done by having a fractional number of lines per field- in the case of PAL, a field consists of exactly 312.5 raster lines (including non-screen area). Now then the VSync kicks in and the raster beam jumps back up, it'll have to traverse half a raster line first, so the following lines come out on screen half a line below the ones of the last field. One 50th of a second later this effect is reversed. And as it's so simple to implement with analog circuitry (you don't have to implement anything at all at the TV side), it was a very good method to halve TV signals' data rate.
Now the problem is exactly that it was so simple. Because the abovementioned old computers and consoles simply don't do 312.5 but only 312 lines. Whoops, no more 1/2 line offset between the fields, the interlacing is gone, all fields have become "full frames" albeit with only half the vertical resolution, and first of all: The refresh rate has gone up. A PAL C64 and Amiga (in noninterlaced mode) output their frames at 50.08 Hz (156.25KHz / 312) instead of 50, with the "wrong" amount of raster lines per field.
You might imagine what consumer-level digital capture hardware which has to decode the interlacing "manually" does with this. To put it short: It simply won't work. Most capture devices simply fail when given the output signal of a C64, Amiga, NES or PS1, or they need to re-sync every 10 seconds or whatever.
And that's why we need those old but still eerily expensive scan converters (Sony DSC-1024) when we record demos for BP. Those beasts simply sample whatever signal is coming in and output in any standard you wish, so they're perfect for making real PAL out of it. And that's why the C64/Amiga demos on BP still drop one frame every 12 seconds, and why interlaced C64 gfx aren't interlaced at all anymore but show perfectly mixed colors (the DSC-1024 makes a "really interlaced" signal out of it, and then the projector de-interlaces that again ;).
Amiga and C64 demos (plus all 8/16bit consoles and the PlayStation 1 ;) have another problem when capturing anyway: They don't even output proper PAL.
Interlacing in analog video signals is done by having a fractional number of lines per field- in the case of PAL, a field consists of exactly 312.5 raster lines (including non-screen area). Now then the VSync kicks in and the raster beam jumps back up, it'll have to traverse half a raster line first, so the following lines come out on screen half a line below the ones of the last field. One 50th of a second later this effect is reversed. And as it's so simple to implement with analog circuitry (you don't have to implement anything at all at the TV side), it was a very good method to halve TV signals' data rate.
Now the problem is exactly that it was so simple. Because the abovementioned old computers and consoles simply don't do 312.5 but only 312 lines. Whoops, no more 1/2 line offset between the fields, the interlacing is gone, all fields have become "full frames" albeit with only half the vertical resolution, and first of all: The refresh rate has gone up. A PAL C64 and Amiga (in noninterlaced mode) output their frames at 50.08 Hz (156.25KHz / 312) instead of 50, with the "wrong" amount of raster lines per field.
You might imagine what consumer-level digital capture hardware which has to decode the interlacing "manually" does with this. To put it short: It simply won't work. Most capture devices simply fail when given the output signal of a C64, Amiga, NES or PS1, or they need to re-sync every 10 seconds or whatever.
And that's why we need those old but still eerily expensive scan converters (Sony DSC-1024) when we record demos for BP. Those beasts simply sample whatever signal is coming in and output in any standard you wish, so they're perfect for making real PAL out of it. And that's why the C64/Amiga demos on BP still drop one frame every 12 seconds, and why interlaced C64 gfx aren't interlaced at all anymore but show perfectly mixed colors (the DSC-1024 makes a "really interlaced" signal out of it, and then the projector de-interlaces that again ;).
Quote:
I'm only looking at capturing a few older pc demos at the moment (well, h+ to be exact :)
ftp://ftp.scene.org/pub/parties/1998/theparty98/in64/hplusavi.zip
jcl: yeah, but as the filename suggests, 'lowquality' :/ (hmm.. think there was a capture on the halcyon dvd actually, maybe that would do)
TVs. Serious business.
kb: What about N64? Is it like Playstation 1?
psonice: I don't deny it might be low quality (I haven't downloaded it so I wouldn't know)... but how does "hplusavi.zip" suggest low quality? :-O
jcl: it doesn't, but the file inside is called something like hpluslowquality.avi ;) Actually it's not too bad, but I'd like a really high quality copy.
psonice: ah, that will teach me to actually download the stuff before asking :-)
I also recall watching hplus on the Halcyon DVD too, should have enough quality I guess, g'luck.
I also recall watching hplus on the Halcyon DVD too, should have enough quality I guess, g'luck.
The huge drawback of the Sony DSC-1024 is that it blends fields together, which is stupid. If you input a 50Hz progressive signal like an Amiga etc. and ask for a regular PAL interlaced output, instead of doing something like this :
frame 1 > top field 1
frame 2 > bottom field 1
frame 3 > top field 2
frame 4 > bottom field 2
...
it's going to do this :
frame 1 + frame 2 (blend) > top + bottom field 1
frame 3 + frame 4 (blend) > top + bottom field 2
I had this exact issue when I did a TV show with videos captured form an Atari STE, the same goes with PlayStation (1) games, N64 etc. (actually quite everything before the last PSOne games and Dreamcast).
That's why in my company we dropped the DSC-1024. Now we're using the Folsom ImagePro HD, which accepts any video timing and video signal (composite, s-video, component, RGB with every kind of sync, SDI, HD-SDI, VGA, DVI/HDMI). It also has a scaler integrated so you can pan & zoom to fit the video into the safe areas for CRT TVs (I need to do that for my current TV show when there's titles in demos). It's a product sold by Barco. The problem is it's more expensive than the (very old now) DSC-1024 and often not available for rental. It does conversions only by dropping fields/frames, no blend or motion compensation - but motion compensation converters are really, really too expensive and don't take RGB or analog video inputs.
frame 1 > top field 1
frame 2 > bottom field 1
frame 3 > top field 2
frame 4 > bottom field 2
...
it's going to do this :
frame 1 + frame 2 (blend) > top + bottom field 1
frame 3 + frame 4 (blend) > top + bottom field 2
I had this exact issue when I did a TV show with videos captured form an Atari STE, the same goes with PlayStation (1) games, N64 etc. (actually quite everything before the last PSOne games and Dreamcast).
That's why in my company we dropped the DSC-1024. Now we're using the Folsom ImagePro HD, which accepts any video timing and video signal (composite, s-video, component, RGB with every kind of sync, SDI, HD-SDI, VGA, DVI/HDMI). It also has a scaler integrated so you can pan & zoom to fit the video into the safe areas for CRT TVs (I need to do that for my current TV show when there's titles in demos). It's a product sold by Barco. The problem is it's more expensive than the (very old now) DSC-1024 and often not available for rental. It does conversions only by dropping fields/frames, no blend or motion compensation - but motion compensation converters are really, really too expensive and don't take RGB or analog video inputs.
The huge drawback of the Sony DSC-1024 is that it blends fields together, which is stupid. If you input a 50Hz progressive signal like an Amiga etc. and ask for a regular PAL interlaced output, instead of doing something like this :
frame 1 > top field 1
frame 2 > bottom field 1
frame 3 > top field 2
frame 4 > bottom field 2
...
it's going to do this :
frame 1 + frame 2 (blend) > top + bottom field 1
frame 3 + frame 4 (blend) > top + bottom field 2
I had this exact issue when I did a TV show with videos captured form an Atari STE, the same goes with PlayStation (1) games, N64 etc. (actually quite everything before the last PSOne games and Dreamcast).
That's why in my company we dropped the DSC-1024. Now we're using the Folsom ImagePro HD, which accepts any video timing and video signal (composite, s-video, component, RGB with every kind of sync, SDI, HD-SDI, VGA, DVI/HDMI). It also has a scaler integrated so you can pan & zoom to fit the video into the safe areas for CRT TVs (I need to do that for my current TV show when there's titles in demos). It's a product sold by Barco. The problem is it's more expensive than the (very old now) DSC-1024 and often not available for rental. It does conversions only by dropping fields/frames, no blend or motion compensation - but motion compensation converters are really, really too expensive and don't take RGB or analog video inputs.
frame 1 > top field 1
frame 2 > bottom field 1
frame 3 > top field 2
frame 4 > bottom field 2
...
it's going to do this :
frame 1 + frame 2 (blend) > top + bottom field 1
frame 3 + frame 4 (blend) > top + bottom field 2
I had this exact issue when I did a TV show with videos captured form an Atari STE, the same goes with PlayStation (1) games, N64 etc. (actually quite everything before the last PSOne games and Dreamcast).
That's why in my company we dropped the DSC-1024. Now we're using the Folsom ImagePro HD, which accepts any video timing and video signal (composite, s-video, component, RGB with every kind of sync, SDI, HD-SDI, VGA, DVI/HDMI). It also has a scaler integrated so you can pan & zoom to fit the video into the safe areas for CRT TVs (I need to do that for my current TV show when there's titles in demos). It's a product sold by Barco. The problem is it's more expensive than the (very old now) DSC-1024 and often not available for rental. It does conversions only by dropping fields/frames, no blend or motion compensation - but motion compensation converters are really, really too expensive and don't take RGB or analog video inputs.
rickst: Then again, an 1:1 mapping of 50p frames to 50i fields would make the image's lines flicker up and down very fast. Also not too nice a thing IMO.
Still you're probably right. But as you said - better solutions are way more expensive and most often hard to rent at all. And there's always the problem that we don't have a second attempt if anything fails, so whatever new hardware we'd use for BP, we'll have to test it beforehand. I've got lots of experience with new, fancy stuff that for some reason wasn't able to do the simplest things - and scan converters are great at that. Eg. on last BP one certain Extron model (that was only used to convert the big screen feed for demoscene.tv) wasn't able to cope with PAL timings on its RGB input, resulting in us having to press two buttons simultaneously (with almost 2 meters space inbetween...) whenever we switched from one of the PCs to a PAL source and back. Oh, and the year before a DSC-1024 decided to make everything completely green when a PC screen mode had 50Hz instead of 60. Good that we had a video mixer with color correction behind that ;)
Still you're probably right. But as you said - better solutions are way more expensive and most often hard to rent at all. And there's always the problem that we don't have a second attempt if anything fails, so whatever new hardware we'd use for BP, we'll have to test it beforehand. I've got lots of experience with new, fancy stuff that for some reason wasn't able to do the simplest things - and scan converters are great at that. Eg. on last BP one certain Extron model (that was only used to convert the big screen feed for demoscene.tv) wasn't able to cope with PAL timings on its RGB input, resulting in us having to press two buttons simultaneously (with almost 2 meters space inbetween...) whenever we switched from one of the PCs to a PAL source and back. Oh, and the year before a DSC-1024 decided to make everything completely green when a PC screen mode had 50Hz instead of 60. Good that we had a video mixer with color correction behind that ;)