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BBC Confirms 50% Bitrate Savings For H.265/HEVC Vs H.264/AVC (bbc.co.uk)
An anonymous reader writes: A research team from the BBC has done a series of tests to confirm earlier computations showing a ~50% savings in bit rate for H.265/HEVC compared to video using H.264/AVC at comparable quality. "The subjective tests used a carefully selected set of coded video sequences at four different picture sizes: UHD (3840x2160 and 4096x2048), 1080p (1920x1080), 720p (1280x720) and 480p (832x480), at frame rates of 30Hz, 50Hz, or 60Hz. The video content was chosen to represent diverse spatial and temporal characteristics, and then coded using HEVC and AVC standards at a wide span of bit rates producing a variety of quality levels." Here is the full published analysis. "The tests confirmed the significant compression efficiency improvements achieved in HEVC, verifying the results previously reported using objective quality metrics (PSNR based methods)." The team did not test against VP9, which is shaping up to be an impressive standard as well.
What is it's Weissman Score?
BBC isn't unbiased here - they have a huge financial stake in saying 50% of the bits produces just as good an image.
Another win for the mobile browsers, I guess.
I've played in this space in a former position. Interesting lessons learned:
- PSNR is nearly worthless: An image with almost the same score can look terrible. Not all the time, but enough of the time.
- The only quantitative test I found that worked reliably was an old analog Tektronix PQA500 (lots of work to use for digital CODEC.)
- Management didn't like the PQA data (it said our product was terrible), decided to use PSNR data (product is great!)
- Customers fixed this discrepancy and product line failed spectacularly (due to video quality, surprise!)
- I never could find any published information sufficient to recreate the Tek PQA algorithm.
You need some serious hardware to play H.265 video without bringing your CPUs to their knees.
50% bitrate reduction vs H.264 sure, but not vs x264 which is the current gold standard for HQ video compression.
It's like comparing a new audio codec to the original fraunhofer MP3 encoder. LAME on the other hand is a significantly better MP3 encoder like x264 is a better H.264 encoder.
My own compression testing between HEVC and x264 show that at verty low bitrates, yes HEVC is better, but only at bitrates below what I would normally use and what I would consider "quality" encodes.
When you compare say a 10GB x264 encode of a full-length BluRay film, even 8GB for the HEVC does not provide an equal or superior copy.
If so then we still can't use it.
The only conclusion that can be drawn from this study is that for encoding at fixed quantization, the JM v18.5 AVC reference encoder is objectively and subjectively worse than the HM v12.1 HEVC reference encoder.
Raise your hand if you've ever used the reference encoder for either.
performing.' Even e3veryday...We
That means it'll take half the time to bittorrent Doctor Who episodes. :-)
So what? Who cares? It doesn't matter.
H.265 is simply far too encumbered by "IP" costs and licensing restrictions to be of any use whatsoever. Sure, there are places (like the douchebags at BBC) who will decide to use it, but rational folks should run from it like the bubonic plague. Especially folks that create content. If you create something that uses H.265 as the master source, your copyright is worthless, because you content is now encumbered inside of format that requires you to pay fees if you want to extract it, convert it, distribute it, or even view it. "It can't really be that bad," you say. Sure, you can buy equipment and software that will do that for you, but part of your cost is the partial fee that the manufacturer is paying for licensing.
Someone have a chat with the BBC about putting resources into VP9 instead. It will save them and everyone else a lot of money, pain, lawyer fees and headaches into the future.
"Somebody has to do something. It's just incredibly pathetic it has to be us."
--- Jerry Garcia
Now they can uncarrier your binge habbits to 0.750 mbps... err, I mean.. "optimize" your video data bits to 6x longer!
I have done my own comparisons of AVC (using x264, single-thread, veryslow preset) and HEVC (using x265, disabling wavefront processing because it slightly reduces quality, veryslow preset). All 1080p video, significant because HEVC is supposed to scale to 4K better than AVC.
My conclusions:
1) x265 takes FAR longer to encode, but we knew that. Understandable.
2) When "low in bits", x265 blurs images rather than making them look blocky. This sometimes looks better but to me often looks worse.
3) x265 seems to force a denoise filter. Video is far easier to encode efficiently when denoised, so I figure this is part of the data savings. It's a bit of a cheat, however, because I can get far smaller file sizes by running a denoise filter myself for x264-encoded video.
I looked closely, for example, at Captain America the Blu-ray. Much of the detail of, e.g. car leather and grass and tree leaves is lost in an x265 encode, even at about the same overall data rate as x265/
x265 supports "--tune grain", roughly analogous to "--tune film" for x264, but it makes the video vastly larger -- often larger than x264's version, and it often looks worse. It does a better job of keeping grain, however.
My experience is very similar to many others' in forums. I had committed to switching my encoding to HEVC, but the results of my tests showed it is not ready for prime time. Some may not mind blurry ("soft" is probably a better word) video, or video that looks like it has been through a denoise filter, but I do.
This is not to say that x265 is junk. I am sure it will mature over time just like x264 had to over time. x264 started out as being not all that much better than divx, the previous generation.
Computer Science is no more about computers than astronomy is about telescopes. --E. W. Dijkstra
What would they know? If you spell BBC in Siryllic you get PRAVDA. Which means 'lying toady lapdogs'.
No commercial pressure, no magic of the market, they just mak things up.
P.S. Vote Trump
--
roman_mir
Cannot be done in anything close to real-time, not with anything close to these results. The thing about this is, patent-holders are tired of having to "give h264 away for free" and are doing a GWX, and any cost. Suck. It. In. and Swallow.
Notice how NO PLACE gets slashdotted anymore?
I've read many many posts indicating that for low bitrate stuff, 265 is doing very well but for the higher end stuff, it's only marginally better than 265 (more like 25%)
That's an approximation, I don't recall the exact figure, but I do recall it being significantly less than 50%
This is pretty disappointing, perhaps other tweaks and improvements will be eeked out over time, but as it stands, I can't see a 3TB movies folder being recompressed to 1.5TB with the same quality at this point in time.
(I know that would be lossy to lossy and stupid, that's not the intention of the post)
Otherwise known as "complete bullshit."
Lawyer up.
"Win treats sysadmins better than users. Mac treats users better than sysadmins. Linux treats everyone like sysadmins."
Because the set of subsisting patents is so large that you can't prove a negative. It costs a substantial chunk of change to deploy set-top decoder hardware for a new data format. Once hardware implementing a decoder for an allegedly royalty-free format has been shipped out, patent holders can come out of the woodwork and claim that their patents apply to the new format. With a patented format, on the other hand, it's more efficient for a patent holder to just join the existing patent pool.
I don't see any mention of how motion compensation and other "smart" features of the display devices influenced the perceived quality. Software in these devices may work in both positive and negative ways.
I prefer to watch my videos on vinyl.
I haven't read the HDCP agreement myself, but I wouldn't be surprised if it forbade modification of the video signal.
Even if this is not forbidden, a DRM scheme operates on the principle that implementations are assumed noncompliant until proven compliant. The fixed costs of an equipment producer joining a DRM scheme include the cost of an audit (possibly probabilistic) of the compliance of the equipment producer's product on behalf of the scheme's maintainer. So even if it were compliant, whether a device is compliant or not does not matter if the prospective manufacturer cannot draw enough investors to make the device exist in the first place.
I haven't read the HDCP agreement myself, but I wouldn't be surprised if it forbade modification of the video signal.
You can definitely modify the video signal - http://support.xbox.com/en-US/...
Looks like there are HDCP certification services that will test your device for under $5000 (Simplay Labs). I assume they would be liable if the device was actually non-compliant.