Maximum video bit rate that make sense?

[JosephTocco]

Hello, let me post my first thread. This will be question.

Blu-Ray releases are in very good quality, both video and audio, but streams bit rate are very high. Higher bit rate in audio it is simply audible (192 and 384 is big difference, but 384 and 1500 are really two different things).

But in video difference is visible really in lower bit rates, for example 1 and 4 mega bits. So question is if extremally high video bit rate makes any sense? 10, 15, 20, 25 mbps? This make ridiculously large files, but in any movie I saw quality is identical like in under 10, 8, and even 6 mbps (for eyes, not for computer).

What maximum bit rate is sensible? I think fps and primarily frame size make quality, not extremally high bit rate, but maybe I'm wrong? What do you think?

[stonesfan187]

I thought I read somewhere that 16Mbps is enough to be transparent with H264 at 1080p when you're compressing a Blu-ray. I am not sure regarding other codecs like MPEG2, VC1 or H265. For compressed files in H264, I would say stick to the 6-8Mbps bitrate for decent results.

[jagabo]

It depends on the particular video, the encoder and settings you use, whether you know what to look for, and how picky you are.

[Hoser Rob]

It depends on the particular video, the encoder and settings you use, whether you know what to look for, and how picky you are.

What he said.

There are lots of videos where SD is perfectly fine for me, esp. Sundance type movies. For some things, (Lord of the Rings comes to mind) I do want HD.

[Anonymous5394]

Hello, let me post my first thread. This will be question.

Blu-Ray releases are in very good quality, both video and audio, but streams bit rate are very high. Higher bit rate in audio it is simply audible (192 and 384 is big difference, but 384 and 1500 are really two different things).

But in video difference is visible really in lower bit rates, for example 1 and 4 mega bits. So question is if extremally high video bit rate makes any sense? 10, 15, 20, 25 mbps? This make ridiculously large files, but in any movie I saw quality is identical like in under 10, 8, and even 6 mbps (for eyes, not for computer).

What maximum bit rate is sensible? I think fps and primarily frame size make quality, not extremally high bit rate, but maybe I'm wrong? What do you think?

Good question! I've always wondered what is the optimal bitrate for blu ray etc when increasing it will not make a difference to the visual perceptional quality. Even making a film in 4k from the original camera negative using the latest compression techniques of hevc would that too have a max out for quality? Does putting it in 8k increase that quality further from the OCN, or is it just reaching the point of diminishing returns?

[JosephTocco]

Yes, we have films of different ages, my oldest one is from '30 of 20th, newest from last year. Capture techniqe is very important too, it may be recorded on film reel, VHS cassette or memory card. But suppose we already have a digital version (digitized or originally digital). We want to encode it in 264, 265 or 266 (in future). There is 720p, 1080p or 4K +.

I'm not picky, I'm reasonable, and don't want to have only a few files on large HDD. Just want to have visually highest quality and the smallest file as possible.

Let's take sample videos:
1 - from 1937 on film reel, digitalized to 1440x1080 15mbps 5GB
2 - from 1998 on vhs tape, digitalized to 1920x1080 16mbps 7GB
3 - from 2011 digital but SD, transcoded to 1920x1080 25mbps 17GB
4 - from 2020 digital true 4K 25mbps 35GB
You could imagine video quality. What parameters will the best to keep visual quality in 264 and 265 and have possible smallest file?
And how about bit rate in 264 and 265? In 265 may be lower?

BTW: I heard that feature film (1.5h) video stream in 4K could have 10GB (something about 12mbps?). Generally x3 smaller than BD.

[Anonymous5394]

I was watching an old dvd boxset of Millennium(the Frank Black one!) the other day and though for SD how fantastic it still looked on my 4k tv. I ripped a couple of episodes to Xvid and H264 as tests for the hell of it, at similar bitrate(I probably could have used half for the H264) and visually I preferred the Xvid. The look and feel of the Xvid was comparable to the DVD source I felt.

I also did the episodes to H265 at much less bitrate-about half) and they looked less filmic than the other two-I won't say washed out, but I lack a proper description to say for definite. I think it is quite subjective and what looks best for your eyes in most cases, but depending on the source input too.

[Anonymous5394]

Crf 18-20 using h264 might be best and going down to crf 16 for archival purposes, but you want the smallest possible size so a 2 pas vbr will be necessary to hit the sizes you wanted. If the source is very grainy high bitrate Xvid might be better as it is said to handle grain much better-that is if you want to preserve it?, H264 will smooth it out some more unless you use a film preset to preserve it etc and H265 may even more smooth grain out, but I'm not sure on this and I don't want to make a sweeping statement. Others will chime on better on this.

What I use for 720p is 2500-5000kbps depending on source.
1080p 5000-8000kps depending on source scenes, if action etc.
I usually use Slow or Slower settings with film preset.

If I encode to Xvid I might consider bits per pixel as 0.2 is considered a good place to start with, but not indicative of final quality as bitrate is a big factor. Even 0.1 for H264 or lower might be okay in some sources. H265 lower still? If you want the best outcome high bitrates would be the preferred option qualitywise, but an unknown size crf over a 2 pass(to get a possible lower and/or stated size!) would be a better option that specific scenes are not starved of quality, but again outcome is down to what you think the result looks like according to you and if you think the sizes are small enough.

[koberulz]

"I want files as small as possible."

"I upscaled a VHS source to 1920x1080i"

Pick one.

[JosephTocco]

"I upscaled a VHS source to 1920x1080i"

No buddy, vhs is under quality, just like some dvd's.

Just want to have visually highest quality and the smallest file as possible.

I though this for 264 (depended on source):
SD: 1-2mbps,
720p: 2-4mbps,
1080p: 4-10mbps (mostly 6-8, as suggested by @stonesfan187),
4K: 10-15mbps (probably 10 is too much anyway).

What do you think?

And how about 265? It is more modern, is it lower bit rate better (in the same br file is bigger as my ffmpeg has produced)?

But all these problems will go away when 266 becomes available

[jagabo]

Why don't you use CRF encoding? You'll always get the quality you specify without worrying how much bitrate to use.

[JosephTocco]

Hmm, that's good question! But the next question is what value to use? 18, 17?

[jagabo]

How would I know what quality is acceptable to you? In my experience, x264 at crt 18 with the slow preset gives results that are almost indistinguishable to the original at normal playback speeds.

[JosephTocco]

A quality where data reduction is irrelevant to perception. Because only to some point there is sense to increase the parameters above which only the file size increases and the image is identical for the eyes, regardless of the device on which you display the movie. Guys, do you understand what I mean? CRF is the point, I must study deeper how to better use it.

[Cornucopia]

What's invisible to distinguish for you might be quite distinguishable for myself or others.

A lot depends on:

• Display size (and distance to display)
• display environment (background contrast)
• display capability
• personal visual sensitivity (to dynamics, color range, detail,...)
• familiarity/criticality of the material
• training

Scott

[_Al_]

A quality where data reduction is irrelevant to perception. Because only to some point there is sense to increase the parameters above which only the file size increases and the image is identical for the eyes

And that point also depends on what was described above. It is a floating point. Do not look for it using a formula. You have your conditions encode CRF 16,18,20,22. Your content on your screen, lighting. A video with dark scenes, action and talking heads. Look at it. Done.

I'm watching a super-bowl , sitting 2 feet from a screen because all seats are taken and suddenly I can see how it is miserably encoded. If sitting on the couch I'd say quality is just fine.

With 4k and above you get another phenomenon. You use CRF and bitrate in nice clean video but with lots of details (picture video of perfectly lit scene, a tree with a billion leaves vibrating in a wind) where bitrate will be elevated into stratosphere values in some moments. So you need to use CRF and cut peaks off. What value for that cut off, that's up to you. Cut off is mandatory for all encoders, but with high resolutions you have to watch those, because you get 100Mbit/s in a heartbeat. You do not care about this if encoding SD video and CRF.
Clean scenes look nice even if using cut-off. BD's have cut-off's too for sure, you can see some movies how it was done as if using scissors (Martian). Some not, and bitrate goes way up and down. All this stuff works in relative terms, there is no answer. For example you have trouble with dark scenes, you elevate bitratr (lower CRF) and cut peaks.

There is no formula. If there was, an editor would just give it to their sons, daughters to encode as a school project to publish it.