Is there a DVD test disc that can display multiple resolutions simultaneously?

January 18, 2009 6:33 PM

Are there test DVDs that can display multiple resolutions simultaneously?

I was looking at a television set that had split screen picture in picture (in this case, a 61" widescreen that could be split to accommodate two large images) which got me thinking about how cool it would be to use the HDMI input and the standard RCA input to play the same video file at 480i and 1080p to really compare the quality.

This made me curious: Are there test discs out there where portions of the screen have been sampled at different rates? It would be an amazingly cool screen test on a huge widescreen HDTV if the screen was divided into segments where the density of information being displayed ranged from 480i and went in standard increments all the way up to 1080p.

Does such a thing even exist and if it doesn't... if I have access to a 1080p video file is there a way to go back and create this mosaic of resolutions I seek? Would it even be valid or would weird things happen like the player itself might try to upconvert and screw the validity of display comparison up?

posted by JFitzpatrick to technology (9 comments total)

You could do this for no cost with a 1080p source and a few high-quality Avisynth resizers to display original and downsampled-then-upsampled side-by-side. For instance:

m1=DirectShowsource("C:\Mysource1080p.mkv",audio=false).Crop(-960,0,0,0)#halfwidth1

m2=DirectShowsource("C:\Mysource1080p.mkv",audio=false).Spline36Resize(853,480).Spline36Resize(1920,1080).Crop(0,-960,0,0)#halfwidth2

StackHorizontal(m1,m2)#lay them out side by side

This will give you a 1080p clip that is half native 1080p and half high-quality upscaled 480p comparable along the X axis.

Encode to a BD-9 structure with your favorite H.264 encoder and Blu-ray authoring software and fire it up! The best source is probably an existing Blu-Ray or HD-DVD or a goog 1080p scene rip.
posted by Inspector.Gadget at 7:02 PM on January 18 [1 favorite]

Oh, the obligatory nota bene: Your test TV may do better upscaling than Avisynth, though it probably isn't noticeable, and this is the only way to get a reasonable side-by-side comparison on a single screen. If you had two identical models you could play a Blu-ray/DVD set with one playing on each, but then you're looking at film mastering differences. I think, though, that a non-simultaneous comparison would be of limited utility.
posted by Inspector.Gadget at 7:04 PM on January 18

Technically there's nothing complicated about this... if you do it all in software. To get 720p next to 1080p:

1) Down sample your 1080p to 720p.
2) Up sample your 720p back to 1080p. Your choice of algos will determine how good it looks. If you can find some data on how your TV or Blu-ray does it that would be best.
3) Now crop each appropriately.
4) Then create a new video by composing your two sources side by side.
5) Finally hook your laptop up to the TV via HDMI, DisplayPort, or whatever and observe!

Doing it in hardware will probably cost something more than you want to pay for a demo.
posted by sbutler at 7:22 PM on January 18

OK, tested the following script and it's working but SLOW: I suggest you find a good 5-minute 1080p source clip because x264 encoding with Blu-ray parameters will be slightly below realtime. You must have a true 1080p source (no cropping) to use the current numbers:

m1=DirectShowSource("H:\Movies\The.Thing.1982.1080p.DTS.HDDVD.x264-hV\The.Thing.1982.1080p.DTS.HDDVD.x264-hV.mkv").Crop(960, 0, 0, 0)

m2=DirectShowSource("H:\Movies\The.Thing.1982.1080p.DTS.HDDVD.x264-hV\The.Thing.1982.1080p.DTS.HDDVD.x264-hV.mkv").Spline36Resize(854,480).Spline36Resize(1920,1080).Crop(0,0,960,0)

StackHorizontal(m2,m1)#lay them out side by side
posted by Inspector.Gadget at 7:23 PM on January 18

Thanks for the replies guys.

I'm reading up about AviSynth right now. If you're checking the replies on this I wouldn't mind a few crash course tips! Is in entirely script based?

Using the script style you demonstrated above Inspector.Gadget, could I modify the screen cropping and number accordingly and add on? i.e. would it be feasible to including 480i 480p 720i 720p 1080i and 1080p in a 2x3 configuration? I'd be displaying it on a 61" 1080 so there would be a fair amount of screen space for each chunk.

One more question regarding the script: will I end up with multiple full screen versions of the (like I had a bunch of TVs side by side) or would I end up with a full screen of the same video with each portion rendered at a different resolution?
posted by JFitzpatrick at 7:49 AM on January 19

density of information being displayed ranged from 480i and went in standard increments all the way up to 1080p.

The density wont be 1080p is you divide the screen. Lets say you have a 1080p screen and you divide into 4 segments of 480x270. All you are doing is downsampling the 1080p image to that resolution. That really wont tell you what the TV looks like in full screen mode. It will just show you how well the downsampled alogrithm works when viewed in a tiny 480x270 box. This might make for a neat demonstration, but the 1080p image will really look like crap compared to what it looks like in full screen.
posted by damn dirty ape at 9:10 AM on January 19

Using the script style you demonstrated above Inspector.Gadget, could I modify the screen cropping and number accordingly and add on? i.e. would it be feasible to including 480i 480p 720i 720p 1080i and 1080p in a 2x3 configuration? I'd be displaying it on a 61" 1080 so there would be a fair amount of screen space for each chunk.

You may only combine progressive content: mixed-in interlacing will not work except possibly with H.264 MBAFF, and that's both beyond the scope of my knowledge and likely impossible to do in this scenario. At any rate, your TV will not deinterlace partially interlaced content flagged as progressive, which will make it unnecessarily ugly.

One more question regarding the script: will I end up with multiple full screen versions of the (like I had a bunch of TVs side by side) or would I end up with a full screen of the same video with each portion rendered at a different resolution?

You will end up with the latter: in the second example script I provided, the left 960 pixel-wdith half of the screen would be upsampled 480p (derived from the original 1080p source) and the right half would be the original 1080p. Bear in mind that the first script I posted will not work because of a few syntax errors I didn't catch, and the second one will work with any source that actually is 1080p. You can adjust the resizing to work with cropped 1080p sources, and you might compare 480p,720p,and 1080p in the following way:

m1=DirectShowSource("H:\Movies\The.Thing.1982.1080p.DTS.HDDVD.x264-hV\The.Thing.1982.1080p.DTS.HDDVD.x264-hV.mkv").Crop(1280,0,0,0)

m2=DirectShowSource("H:\Movies\The.Thing.1982.1080p.DTS.HDDVD.x264-hV\The.Thing.1982.1080p.DTS.HDDVD.x264-hV.mkv").Spline36Resize(1280,720).Spline36Resize(1920,1080).Crop(640,0,640,0)

m3=DirectShowSource("H:\Movies\The.Thing.1982.1080p.DTS.HDDVD.x264-hV\The.Thing.1982.1080p.DTS.HDDVD.x264-hV.mkv").Spline36Resize(854,480).Spline36Resize(1920,1080).Crop(0,0,1280,0)

StackHorizontal(m3,m2,m1)#lay them out left-right from 480p to 1080p, with each 640 pixels wide

This will be a SLOW script and will still require a true 1080p source. Note that you can swap Spline36Resize for a resizer more to your liking; Spline64Resize will be sharper but slower, and as always there's a struggle between preserving sharpness and avoiding artifacts from oversharpening.
posted by Inspector.Gadget at 10:12 AM on January 19

Fascinating stuff. I haven't messed around with video editing in years and years and certainly not with any recent HDTV stuff.

So as I understand it... reasonably speaking it's nearly impossible make the interlaced and progressive combination and even if I did it would be completely inaccurate because the display couldn't possibly deal with the the progressive/interlace combo? Makes sense.

I think a great candidate for this project would be the open-source/creative commons movie Big Buck Bunny. It looks gorgeous in 1080! This will be an enormously interesting experiment. I'll post an update here when I've put it together and given it a test run.
posted by JFitzpatrick at 2:16 PM on January 19

So as I understand it... reasonably speaking it's nearly impossible make the interlaced and progressive combination and even if I did it would be completely inaccurate because the display couldn't possibly deal with the the progressive/interlace combo?

I should have said "Blu-ray player or HTPC" instead of TV, but yes. BTW, check out these two stills I made using the retail Blu-ray of "RV":

Single frame, 640px width sections, with original 1080p at right, upsampled 720p center, upsampled 480p at left.

Single 640px width frame section, repeated from left to right in upsampled 480p, upsampled 720p, and finally original 1080p.

This doesn't tell us anything about the display, but illustrates what a good quality resizer can accomplish.
posted by Inspector.Gadget at 5:50 PM on January 19