~8GB MKV - 1080p or 720p?

[hogger129]

Hi guys,

I am ripping and converting my BD collection and have limited space to work with. I want to do ~8GB MKV files. The largest TV I am viewing these on, is a 42" LCD TV, sitting about 8-10 feet away from the TV.

Should I use 1080p or is 720p good enough? I am guessing that I would likely not be able to tell the difference until my screen size was 50" or more.

Please share your views and opinions.

Thanks,

hogger129

[jman98]

MOST human beings just aren't all that picky and wouldn't be able to tell a difference - period. That doesn't mean that you won't get posts here swearing that EVERYBODY on earth will certainly be able to tell a HUGE difference and if you do 1080p you are an idiot, blah blah blah. You could just do both and see what you think but based on what I said previously, I think you could go with 1080p and it would probably be fine for you

[deadrats]

Hi guys,

I am ripping and converting my BD collection and have limited space to work with. I want to do ~8GB MKV files. The largest TV I am viewing these on, is a 42" LCD TV, sitting about 8-10 feet away from the TV.

Should I use 1080p or 720p? I am guessing that I would likely not be able to tell the difference until my screen size was 50" or more.

Please share your views and opinions.

Thanks,

hogger129

since you've decided to limit yourself to a fixed target size that means you will be limiting yourself to a certain bit rate. within those parameters, assuming similar encoder settings, one would expect the 720p file to have a higher per pixel quality than the 1080p file, since they both would be using the same bit rate and starting from the same source.

of course, you could do a test encode where you used a 3rd BD legal resolution, one that isn't used all that often, namely 1440x1080 with 4:3 pixels, which gives you the same aspect ratio as 1920x1080 or 1280x720 with square pixels. with this target resolution i would use more aggressive encoder settings, only because thanks to the larger than 720p size the theoretical per pixel quality of the 1440 file versus the 720p file would be lower within that size restriction but the resolution would be close enough to the 1920 source that any lose of quality due to reduced resolution would be minimized.

[jman98]

since you've decided to limit yourself to a fixed target size that means you will be limiting yourself to a certain bit rate. within those parameters, assuming similar encoder settings, one would expect the 720p file to have a higher per pixel quality than the 1080p file, since they both would be using the same bit rate and starting from the same source.

You are quite right but let's be honest. How many people do you know outside of your immediate family who actually switch their TVs between 4:3 and 16:9 depending on the source? I know exactly ONE - my brother. Given how almost everybody just watches EVERYTHING in 16:9 anyway, I think it's pretty fair to say that most people won't notice any difference between 720p and 1080p. Hell, they watch 4:3 in stretched 16:9 mode without complaint. The odds are much higher that the OP won't notice or care than he will, although technically speaking you are correct.

[Hoser Rob]

... The largest TV I am viewing these on, is a 42" LCD TV, sitting about 8-10 feet away from the TV.

Should I use 1080p or is 720p good enough? I am guessing that I would likely not be able to tell the difference until my screen size was 50" or more...

I've seen stuff where they actually crunched the numbers. Based upon screen pixel size, viewing distance, the size of the receptors in you eye etc.

For someone with average normal 20:20 vision at 9 feet from the screen, which is the median distance, at 1080p you'd need a 70" or more screen to actually be able to see the detail of that resolution.

At about 2.7 or so times the distance to the screen you can't tell the difference between 720p and 1080p. Note that with a 42" screen aty 10 feet, as the OP mentioned, you're awfully close to that ratio.

However, 8Gb is a pretty good size file. If you know what you're doing with encoding at all I think you'd be pretty safe with 1080p.

[hello_hello]

Hi guys,

I am ripping and converting my BD collection and have limited space to work with. I want to do ~8GB MKV files. The largest TV I am viewing these on, is a 42" LCD TV, sitting about 8-10 feet away from the TV.

Should I use 1080p or is 720p good enough? I am guessing that I would likely not be able to tell the difference until my screen size was 50" or more.

Please share your views and opinions.

When I convert Bluray video I create an Avisynth script without any reasizing, then another resized to 720p, and I open them both with MPC-HC while running them fullscreen on my TV (51") which is about 5" from my desk. More often than not, I go with 720p because if there's a loss of detail it's extremely negligible. Especially if I use any noise filtering which tends to blur a little anyway. Some video does have more than 720p worth of picture detail but if anything, often it's really only more than 720p worth of noise. When I'm deciding on resolution I'm pretty close to the screen and I've usually got to stop each on identical frames and switch between then to really tell if there is a difference. Back at normal viewing distance I doubt I could pick 720p from 1080p.

If you're going for a rule of thumb, single DVD size for 720p and dual layer DVD size for 1080p is probably reasonable. Keep in mind the resolution police won't knock on your door if you use something other than 1080p and 720p. I've used 900p a few times when 720p does seem to be costing me a little bit of detail (1600x900 before cropping).

I'd forget file sizes to a certain extent. Pick a CRF value (quality) which gives you a quality you're happy with and use whichever resolution you think is required for each video. The file sizes will vary all over the place but the average will probably come in under 8GB. I've done 720p encodes using CRF18 which were under 3GB and 1080p encodes of up to around 10GB. I suspect you could encode everything at 1080p and probably still average 8GB. Maybe someone who encodes a lot at 1080p will know.
I don't keep DTS audio as on average it'd be over 1GB per movie, so I keep the AC3 audio instead or convert DTS to AAC.

[hello_hello]

One other thought....
You can generally get away with increasing the CRF value a bit (lower quality) when encoding 1080p video. I try to encode everything at CRF18 but for 1080p if the file size looks like it's going to get out of control I increase it to CRF20, but it's all personal preference. If I had to choose between lowering the resolution and lowering the quality a lot in order to achieve a particular file size though, I'd go with a lower resolution.

[fritzi93]

Looking at a couple hundred 1080p CRF20 encodes I have on one drive, the average file size seems to be right around your desired figure of ~ 8 GB.

The advantage of quality based encoding is you can get approx the same quality each time. Content varies in compressibility, for example, comparing two of those encodes, Wall-E is 2.81 GB while Saving Private Ryan is 19.1 GB. The first is very clean animation, the second is very grainy film. A target size of 8 GB means you're under or over compressing almost every time.

Note that preset speed also affects file size when using CRF encoding. I use a fairly slow preset.

So try a test 1080p CRF20 encode and see if that's acceptable. I find it to be good enough on a 70" Sharp at a viewing distance of 8 feet. At your viewing distance 720p would be fine, but you won't own that TV forever, and will get a bigger one someday, yes? You don't want to do everything over again when that day comes.

[EDIT] To clarify, view that test encode at ~ 6 feet viewing distance to see if that's acceptable. At my viewing distance/TV size, I have to look awfully hard to tell the difference between CRF18 and CRF20. Normal viewing, not pixel-peeping.

[hello_hello]

After my rant regarding 720p being fine a lot of the time.....

I guess one disadvantage/consideration when encoding at 720p is how sharply the video is resized to 720p when encoding and how sharply it's resized back to 1080p on playback. I do my testing with MPC-HC and I generally resize to 720p with a fairly sharp resizer (spline36).

MPC-HC lets you choose a resizer in it's settings. There's a difference between a soft resizer and a sharper one when viewing 720p video fullscreen. I think most TVs/Bluray players use a fairly sharp resizer but they're not necessarily the same. My Samsung TV's internal upscaling looks a little sharper to me than my Sony Bluray player's upscaling. Once again the difference is probably something you'd not see back at normal viewing distance although the sharpness of the resizer may have a slight effect on the graph fritzi93 posted above.

When I check 720p video with MPC-HC using a soft resizer (up close) there's generally a little blurring compared to 1080p. Switching to a sharper resizer usually fixes that. Occasionally a 720p video resized back to 1080p using a sharpish resizer can appear to have slightly more detail than the original, or at least look a tiny bit sharper, but that's all fairly "sit close to the screen, comparing individual frames, nitpicking" stuff.

If you're really paranoid about a loss of fine detail though, fritzi93's suggestion of encoding everything at 1080p using CRF20 is probably the way to go. That way there's no resizing involved. If you're more concerned with file size though, maybe try encoding a small section of video at 1080p and again at 720p (or even 900p) to compare them yourself before you decide.