Questions about 4K?

[tommy2010]

Hi there,

With 4K videos starting to pop up what is the best software out there for transcoding, something along the lines of multiavchd? Also is there something similar to tsmuxer available but for 4K? Finally what about playback? I believe VLC plays 4K but is there something better? For any of you that have some experience with 4K remuxing and compression I would love to hear your thoughts on the subject and software recommendations.

Thanks,
Tom

[LigH.de]

"4K UHD" is a resolution; it means: 3840 × 2160 pixels. There is no reason why any converter which was good at lower resolutions would suddenly be worse at this higher resolution, for the same choice of codec and settings.

But...

To compress such a higher resolution to still manageable bitrates with acceptable visual quality, one would prefer using a different video format, and a different encoder than for lower resolutions before. For HD resolutions 720p and 1080i/p, you may have preferred AVC (e.g. using x264 as encoder) — now for 2160p, you will probably prefer HEVC (e.g. using x265 as encoder). Compared to AVC, HEVC is even more complex, already needs much more CPU power to be decoded, and even more to be encoded.

And encoding is only the part of creating the video content. The next step is authoring a logical media structure accepted by consumer players. For HD content with AVC video, the Blu-ray or the AVCHD media formats belong to the most common consumer formats. For UHD content with HEVC video, there is no really common consumer format yet, so there are not many software tools to produce them either. Just like AVC video, you can multiplex HEVC video streams into MP4, MKV, or M2TS containers; but that would only be a single movie file as result, not a whole consumer media format (with possible remote control guided menus and additional extra content).

Stay tuned; have a look into the VideoHelp Software archive once in a while, in the category of authoring software for the successor of Blu-ray for UHD resolutions with HEVC video, whatever its name will then be, when it developed into an advertized consumer format.

[SameSelf]

We are finally starting to see some things show up in the wild for UHD Blu-ray: Link. Given that these will be essentially triple layer discs, I am hopeful the technology will eventually find its way into the PC space via writers and blank media. I am a big fan of DL BR discs for archiving.

On a side note though: One has to really wonder why the studios want to release titles so close to master quality.

[sophisticles]

On a side note though: One has to really wonder why the studios want to release titles so close to master quality.

Because the only way to get people to buy physical media is to offer them something that digital downloads can't offer. NetFlix, Hulu, YouTube, all these streaming services are killing traditional distribution media, but start selling near-master quality 4k UHD Blu-Ray and maybe some people will be willing to spend $20-$50 on a disc that contains a movie they can watch for $3 online.

[LigH.de]

Remember, the world is not yet gaplessly connected with broadband lines, there are still distant areas with less reliable and less powerful technology. Even in the middle of industrial flagship states ... like countryside in Germany ... so "streaming" is not always a solution. And after all, if you can't afford it with your wages, it doesn't matter much what format you can't afford, and any alternative for free is good enough.

In addition, I belong to the people who doubt about the future of recordable optical media.

[Cornucopia]

The idea of equating a 2-10Mbps streaming UHD movie to a 66-128Mbps UHDBD movie is laughable, given that, at best, they're both going to be using the same encoding (H265). Then there's HDR, Atmos/DTS-X, heck even Menus & Chapters...

Quality, quality, quality.

Scott

[Cornucopia]

BTW, the Blu-ray Disc Association has updated their Technical White Papers (http://www.blu-raydisc.com/en/Technical/TechnicalWhitePapers/General.aspx) for those who are inclined to ~inspecting just what is possible with UHDBD. Much more thorough than anything else I've seen yet. Still doesn't address new copy protection (which I'm guessing would have been greatly beefed up).

Scott

[SameSelf]

I am curious about this HDR aspect from a post-production workflow aspect. I have been looking at this for a while now. Rec. 2020 for UHDTV, while it has a larger gamut, to me the more interesting aspect is the 10-bit/12-bit color requirements. Even if you are targeting an 8-bit delivery format, 10-bit is critical to many post-production workflows (e.g. color grading and according to this). But 10-bit support in software is limited. Just look at the first line from the Avisynth wiki here (not very encouraging). I am just beginning to audit my workflows to see where they fall down from my 10-bit ProRes 422 masters all the way to the final transcode, even if it is 8-bit BD.

I am curious what others thoughts are on hardening their workflows for 10-bit. It may be a pay-to-play scenario. I have looked into getting 10-bit monitor support for my editing station, but hardening the signal chain is difficult and expensive.

So, while something like multiAVCHD might work fine for 8-bit delivery formats, what about 10-bit support? If x265 comes up with a UHD compliant setting a la x264 bluray compliant, how to I frameserve my video to x265 and maintain 10-bit integrity?

To me, those are the most important pieces of the puzzle: 1) ensuring that the workflows stays in 10-bit, and 2) coming up with an x265 UHD compliant setting that doesn't trigger any transcode flags in the authoring package.

[sneaker]

If x265 comes up with a UHD compliant setting a la x264 bluray compliant, how to I frameserve my video to x265 and maintain 10-bit integrity?

x265cli supports 10 bit/16 bit raw or y4m input just fine. You can use the AviSynth high bitdepth hack in some plugins or VapourSynth and pipe.

[Cornucopia]

There is a spectrum of "disruptiveness" in theses new technologies...

Least is UHD resolutions. More (4x or 16x) of the same we've been working with. Clearly this affects filesizes, and bitrates. So that affects drive capacities & speeds, as well as transfer/display bandwidth. Other considerations are with codec choice (allowing that size as input/output) and cam & display support.

Next up the ladder is HEVC. Not All UHD utilizes HEVC (source & DI edit formats, for example), but most will need to if you don't want to go crazy upgrading ALL of your subsystems. But HEVC comes at the cost of increased horsepower requirements, both encoding & decoding, both during production and during consumption. Plus, you have to correctly match the Profiles/Levels to the material & playback devices in order to get good return on your attempts.

Sounds like you already have those in hand at least.

The next level up is 10bit through-and-through. I say it that way because you don't get the full benefit of 10bit unless you've got all elements in the chain capable of it. This upgrade involves ALL the capture, edit/process, and display chains including software, hardware, drivers, and OS (unless the software used bypasses the OS graphics services). While you can do elements of 10bit on-the-cheap/free, it's not possible to complete the chain that way, and I would say you are doing yourself a disservice creating Rube Goldberg islands in the attempt to avoid commercial/licensed solutions.

Next up is WGC, and there are NO decent software workflows that rely on anything but commercial/professional software/hardware for this. You'll need high end, calibrated monitors and new forms of waveform/signal monitoring to say the least. BTW, 10 or 12bit, or higher, is a necessity for WCG to avoid banding.

Hardest to do will be HDR, because you will in effect be having to master TWICE (once for HDR, once for SDR), and will have to have tools for conversion, comparison, backward/forward compatibility/enhancement translation, etc. Plus you should also have side-by-side HDR+SDR monitoring hardware, calibrated & matched AFA corresponding standards will allow. This is all ON TOP of all the other hardware & software upgrades, so it will likely be the sole province of the "big boys" for quite a while. (Most HDR formats rely on 16/32/64bit (integer or float, depending) to handle the wide linear range without artifacting. Again, more data & more bandwidth.)

Plus, I'll restate what I've written here long before: this next wave media tech will truly inaugurate a TIERED system, where it seems the only the Highest end pros & Richie riches can afford to both produce & consume the highest fidelity stuff, then there'll be the upper-middle area (corp., business...) which can afford less frills (but still quite good) UHD, then your average middle class producer/consumer/presumed still utilizes decent HD stuff, and the lower classes/poor/disaffected are left with SD and analog. Sure looks like it's coming true...

Scott