Are same resolutions of equal PQ, compressed codec or otherwise ?

[Seeker47]

This question could probably be placed under 2 or 3 forum categories.

Let's say you have the same contents video in 1080P, in a couple different formats. One is H264 or X264, to a size of around 5 GB. The other is the highly compressed HEVC, taking up only about 1.5 GB. Of course, there may be some other differences -- framerate, or whatever. Do you think that you would be likely to detect any quality differences ? And not only during action or fx scenes ? Does the higher compression reliably "give up" anything ? (Like it certainly does in, say, MP3 audio, vs. WAV or FLAC ? Yes, I understand that MP3 is also just a sampling of the original source.)

I'm not entirely sure about this, but I think the HEVC version definitely looks darker when played on the computer, almost regardless of the scene lighting. I suspect that it may also play somewhat darker when streamed / played on your bigscreen tv. Relative sharpness or detail is a more uncertain question. Trying to see if this is subjective perception vs. something perhaps quantifiable.

[jagabo]

It depends. every video is different. But generally, yes, the HEVC video at 1.5 GB is likely lower quality than AVC video at 5 GB. At 3 GB the HEVC video would likely be closer to the AVC video.

The first thing to go with lower bitrates is small, low contrast detail. Things like film grain, leaves of trees in the distance, light wood grain, etc. Especially when those things are in motion.

Color/brightness shouldn't be different just because the codec. That's caused by something else.

[Seeker47]

Thanks, jagabo. That confirms at least part of my suspicions. (I'd say the apparent level of brightness -- at least when viewed on the computer -- is definitely a thing, though.)

[jagabo]

I'd say the apparent level of brightness -- at least when viewed on the computer -- is definitely a thing, though.

That has nothing to do with the AVC vs. HEVC compression. My guess is your HEVC video is HDR, the AVC video SDR. Or whoever encoded them made one brighter or darker. Or maybe the player you are using is set up to handle them differently.

[Seeker47]

I'd say the apparent level of brightness -- at least when viewed on the computer -- is definitely a thing, though.

That has nothing to do with the AVC vs. HEVC compression. My guess is your HEVC video is HDR, the AVC video SDR. Or whoever encoded them made one brighter or darker. Or maybe the player you are using is set up to handle them differently.

My Go To player on the desktop is VLC 3.something, with defaults unchanged. If VLC can't play a video file, I know I'm probably in trouble, and most of the others wouldn't fare any better. In fact, when I take a "problem" file over to MPC_BE it's likely to show a "not enough pins for playback" error -- whatever that means. You may be on to something with the HDR surmise, as that attribute seems to be taking hold pretty widely. I know next to nothing about HDR, having mostly ignored the subject. It hasn't been relevant to the gear that I have or use. I mean, I'm viewing this on a (very good) CRT monitor, as I type. Dinosaur time, I guess. If something ain't broke and seems to still provide good results, I tend not to replace it.

I could post some clip samples, if that would be of any help. (Or sometimes MediaInfo might offer a clue ?)

[jagabo]

HDR can look very bad if not converted to SDR for display on an SDR system. Here's an example of a bad conversion on the top, a good conversion on the bottom (originally 4K video):


[Attachment 57908 - Click to enlarge]

Here's what MediaInfo says about the video:

Video
ID                                       : 257 (0x101)
Menu ID                                  : 1 (0x1)
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5.1@High
HDR format                               : SMPTE ST 2086, HDR10 compatible
Codec ID                                 : 36
Duration                                 : 3 min 17 s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 59.940 (60000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 10 bits
Writing library                          : ATEME Titan File 3.7.9 (4.7.9.0)
Color range                              : Limited
Color primaries                          : BT.2020
Transfer characteristics                 : PQ
Matrix coefficients                      : BT.2020 non-constant
Mastering display color primaries        : Display P3
Mastering display luminance              : min: 0.0500 cd/m2, max: 1000 cd/m2

[davexnet]

Post some samples if you can

[Seeker47]

HDR can look very bad if not converted to SDR for display on an SDR system. Here's an example of a bad conversion on the top, a good conversion on the bottom (originally 4K video):


[Attachment 57908 - Click to enlarge]

Yup, that effect definitely looks familiar.

[Seeker47]

Post some samples if you can

This might not be a good example, but it's a first try on this. It's HEVC, however I don't see any HDR notation in MediaInfo -- not in the excerpt, nor in the source. It was chosen because I wanted to stick to outdoors shots that were made in daylight. I think I could supply samples that were more like the one from post #6.
sample.mkv

[EDIT: On reflection, further samples may be unnecessary, as I think the stills from #6 pretty much nails what I was describing. The exception would be if further (clear) cases I run across are demonstrated to be non-HDR.]

[When I playback on the bigscreen tv, it is on 1080P max. plasma, which must predate HDR.]

[Cornucopia]

AFAIK, ALL plasma displays pre-date HDR. (At least, the hdr video formats currently presented to consumers)


Scott

[jagabo]

This might not be a good example...

[Attachment 57959 - Click to enlarge]

That sample is normal 10 bit SDR.