16 Mbps is probably about as high as you need to go.

Even lower using crf in Handbrake. Start at around 12 Mbps and inch up until you no longer see an improvementnt

You might be getting bitrate confused with resolution. Your bitrate limitations are placed by the delivery medium. In this case, Bluray is limited to around 35Mbs, but normally runs around 15 to 20. But if you are using some other medium, such as a media player, it could run 60Mbs or higher depending upon the capabilities of the player.

So with my source file I could have an AVC MP4 at 1080p at 60Mb/s without any quality issues? And a blu ray at max that is supported?

16 Mbps is probably about as high as you need to go.

Even lower using crf in Handbrake. Start at around 12 Mbps and inch up until you no longer see an improvementnt

So there is a maximum bit rate when I downscale it from 4k 60Mb/s? Or could I go to 28Mb/s (blu ray max) if I wanted to?

There is no maximum bitrate other than the Bluray specifications. I think what Musicvid is indicating is there is a point of diminishing returns. At what bitrate do the gains not justify the increase in file size?

There is no maximum bitrate other than the Bluray specifications. I think what Musicvid is indicating is there is a point of diminishing returns. At what bitrate do the gains not justify the increase in file size?

So my plain question is this: when I downres to 1080p what is the maximum bit rate I can get from the source file at 4k 60Mb/s?

There is NO maximum bitrate. You can make it whatever you want. You could even make it 120Mbs, but there would be no point to doing it because you would not gain any quality, only increase the file size. So you have to determine what bitrate you want to use based on your final delivery/viewing platform.

There is an OPTIMUM bitrate and that is what Musicvid is presenting.

There is NO maximum bitrate. You can make it whatever you want. You could even make it 120Mbs, but there would be no point to doing it because you would not gain any quality, only increase the file size. So you have to determine what bitrate you want to use based on your final delivery/viewing platform.

There is an OPTIMUM bitrate and that is what Musicvid is presenting.

No no no. I'm asking what is the max bit rate I can make my downres-ed file KEEPING ALL QUALITY from 4k 60Mb/s to 1920x1080 at X Bit rate? Is it 60Mb/s divided by 4 or what?

I'm not sure you are getting my question here.

Sorry, it doesn't work that way. You will not keep all quality from the 4k at any bitrate because you are throwing out so many pixels when downrezzing. The damage is done in changing resolutions not in adjusting bitrate. Once you lose those pixels, you lose any quality equivalence.

Sorry for being mean. I'm having a stressful time with something else note related - and that's no excuse.

So would you say the theoretical maximum bitrate I could have in 1920x1080 (trying to be highest quality) would be 1/4 of the bitrate of the 4k source file? And would that be 15Mb/s?

Thank you for the Solution tick. We work cheap around here.

Now, I have spared no expense to prepare a graphic showing what really goes on here. Quality metric (SSIM) vs. Bitrate in a relative (not literal) relationship, but close enough for our purposes. As you can see, SSIM is a logarithmic function of Bitrate (x-scale value), where it never quite reaches parity with "perfect" quality (SSIM 1.0).

Need to note here that the x-scale values are not actual bitrates, just linear Index points. In your case, because David and I are both familiar with your source characteristics, the yellow dot (Optimal SSIM of 0.950) may occur at about 12-15 Mbps. Above that is just plain silly. Below that, you've still got a lot of legroom for really great quality with a lot less soaring in the file size.

This is how it is before any scaling takes place.

Now, before David's head explodes from holding his laughter, I'll spill the beans. This whole lesson is almost totally irrelevant because you are downscaling your video! in fact,it seems that achieving a 0.750 SSIM may be theoretically impossible (I'll test this some year) because the new resolution retains only 25% of the source data by any downscaling means (it really doesn't matter much unless you are upscaling). So, your new Optimal bitrate target may actually be <=12 Mbps, especially if you are using x264 CRF. Add to that the temporal effects on the brain, you should be OK at 12Mbps unless you see artifacts in the fades and transitions.

That, my friend, is entirely up to your eyes, your viewing screen, the all-important encoder, and of course your source video itself. That is also the reason why we are deliberately vague about addressing arithmetic theories when in fact the equation is far more complex.

Eagerly awaiting the outcome of your tests on your setup.

[EDIT /] It is hard to create a valid .m2ts for Blu-ray from x264 because that includes a number of compression tricks that are not in BDMV spec.

I did a test with Sony AVC (MS14) 18Mb/s and it looked fabulous on a blu ray.

The 4k source is just for archive purposes and if the client wants a 4k master.

Thanks for you guys' help.