Talk:High Efficiency Video Coding

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This article uses American English dialect and spelling.
According to the WP:ENGVAR, this should not be changed without broad consensus.

Tidying up[edit]

Needs to be tidied up a bit. Should really be updated once the JCT-VC meeting report and subjective test reports are completed. Iainerichardson (talk) 17:39, 3 May 2010 (UTC)

The Features section sure needs to be updated, however there is too much technical information and too many proposals to make a short summary. Somebody with a good understanding of video coding technology is needed. Might as well wait for a summary of the proposals at the July 2010 meeting to update the section. --Dmitry (talkcontibs ) 06:47, 14 June 2010 (UTC)
It seems like people were talking about cleaning up this article almost 4 years ago. I've added some tags to help encourage a cleanup of the article. TekBoi [Ali Kilinc] (talk) 23:13, 21 February 2014 (UTC)
The article has changed greatly in the last 4 years. The number of section headings doesn't violate any Wikipedia policy and is less than many of the featured articles I have read, the prose size of the article is below the point at which splitting is recommended, and I don't see how the article has a problem with quotations when it has only a few short quotes in it. --GrandDrake (talk) 17:33, 22 February 2014 (UTC)

Tools update[edit]

I added more descriptive text on each of the coding tools and removed the update note. Pieter3d (talk) 07:54, 8 July 2012 (UTC)

"High Efficiency Video Coding" is accurate[edit]

The article was recently moved without discussion and it had to be moved back with a requested move. I would mention that "High Efficiency Video Coding" is accurate and is used on the Joint Collaborative Team on Video Coding website, the organization that is developing HEVC, and is used in the HEVC draft specification. --GrandDrake (talk) 00:55, 13 November 2012 (UTC)

The size of the levels chart for HEVC[edit]

The concern I have with having a lot of examples in the levels chart is that it harms the readability of the chart. If you think that those examples are needed on Wikipedia what do you think about the idea of having them in a HEVC levels article? --GrandDrake (talk) 06:47, 27 November 2012 (UTC)

  • If you remove resolutions from the levels table, sync this with the relevant table from H.264/AVC. I do not understand their choice of resolutions either (and it used to be much leaner as well), so I can't give opinion about including very similar resolutions, but I strongly feel these tables should be cross-synced between the two articles, so that direct comparisons can be easily made. --Dmitry (talkcontibs) 19:44, 27 November 2012 (UTC)
Created the High Efficiency Video Coding tiers and levels article which has a chart with most of the maximum level resolutions for H.264/MPEG-4 AVC including resolutions such as 1280×1024, 3672×1536, and 4096×2304. --GrandDrake (talk) 03:01, 28 November 2012 (UTC)

Proposal to move article to H.265/HEVC[edit]

Since the ITU announced in a press release that the ITU will use H.265 for HEVC I propose that the article be moved to H.265/HEVC. --GrandDrake (talk) 00:35, 28 January 2013 (UTC)

Actually, that press release primarily refers to the standard as HEVC rather than H.265. It just says that ITU-T H.265 is one of the two ways the standard is formally identified, but continues to use the name HEVC in the rest of the press release. —Mulligatawny (talk) 18:49, 29 January 2013 (UTC)
I agree. Even if the final ITU nomenclature is H.265, the current name has already achieved quite a notability. "High Efficiency Video Coding" is the most common name which reflects the content of the article quite well and a much friendlier one to the average user (in fact I would rather rename H.264/MPEG-4 AVC to Advanced Video Coding for the same reason). And if we rename to "H.265/HEVC", some nitpicker will certainly come out and rename it to "H.264/MPEG-H Part 2 HEVC", etc. --Dmitry (talkcontibs) 16:26, 2 February 2013 (UTC)
I agree that some of the video standard articles on Wikipeda don't follow Wikipedia:Article titles with one example being H.262/MPEG-2 Part 2. I would strongly oppose any proposed article title for HEVC that includes "Part 2" since that would be confusing to the average reader and overly precise. I guess it would make sense to wait and see whether HEVC will remain the most common name before considering any changes to the article title. --GrandDrake (talk) 06:46, 8 February 2013 (UTC)


IBDI is listed as a coding tool. However, there is no IBDI coding tool in the FDIS. IBDI can be realized with any video format by padding zero LSBs before encoding and truncating/rounding/dithering after decoding. As such it is an encoder feature, and not a coding tool of the video format. IBDI is only possible if the maximum allowed bit-depth of the video format is greater than the input bit-depth. If the input video is 8-bit, then any format which allows bit-depths greater than 8-bit can perform IBDI. But in the broad sense, any video format with more than 2-bit bit depth can perform IBDI for 1-bit input, so it can be classified as performing IBDI. Practically though, I think the "more-than-8-bit" (strict sense) definition is more useful. For example, H.264/AVC can also use more than 10-bit bit depth, but there it's rarely referred to as IBDI (see e.g. "10bit-depth output information" on [1]). From my point of view, IBDI should either be removed from the HEVC article or added to the H.264/AVC article (and any article of a lossy video codec which supports bit-depths over 8-bit), for the sake of consistency. Conquerist (talk) 21:57, 27 April 2013 (UTC)

That explains why there isn't any mention of IBDI in the HEVC draft specification or in "Overview of the High Efficiency Video Coding (HEVC) Standard" which covered HEVC coding tools. Since IBDI is it not a HEVC coding tool I removed that section from the article and moved the references to the statement in the Main 10 section about improved coding efficiency when video is encoded at a higher bit depth. --GrandDrake (talk) 02:43, 28 April 2013 (UTC)

Opening remarks[edit]

HEVC is said to improve video quality and to double the data compression ratio compared to H.264/MPEG-4 AVC.

I'm not sure I like the wording of this. "double the data compression ratio" implies (as is mentioned further down) a measurement at the same subjective quality (otherwise simply "doubling the data compression ratio" is meaningless since you can select whatever ratio you like in both H.264 and H.265). Either you can improve the video quality or you can keep the same quality and double the compression ratio. David (talk) 11:41, 8 August 2013 (UTC)

Changed the statement so it only mentions the data compression ratio. --GrandDrake (talk) 03:37, 9 August 2013 (UTC)

What we are trying to say is that HEVC is said to have twice the compression efficiency of AVC. This means that HEVC can encode video at the same subjective visual quality, using only half the bit rate. Alternatively, a doubling of compression efficiency can provide substantially higher visual quality at the same bit rate as AVC. Tvaughan1 (talk) 06:05, 23 July 2015 (UTC)

Should "bits per color" be changed to "bits per sample"?[edit]

I used "bits per color" in the article since the term was more common on Google search results but the HEVC standard does say "bit depth of the samples" and documents from the people who are working on HEVC, such as "Overview of the High Efficiency Video Coding (HEVC) Standard", use "bits per sample". Should "bits per color" be changed to "bits per sample"? --GrandDrake (talk) 22:55, 10 August 2013 (UTC)

No. "Bits per color" or "bpc" is more common and more appropriate for overview sections.
However, in the technical sections, we should refer to YUV color model as in the text of the standard, using "luminance/chrominance sample" and correspondingly "bits per luma/chroma sample", "bits per sample", etc. instead of RGB terms such as "color" or "bpc". --Dmitry (talkcontibs) 06:40, 11 August 2013 (UTC)
I changed the first use of "bits per color" to "bits per color/sample" so people will know that they are the same thing, changed "bits per color" to "bits per sample" in the technical sections, and added a note about luma/chroma bit depth to the profiles chart. --GrandDrake (talk) 21:21, 11 August 2013 (UTC)
A "color" is typically represented as a set of three ("tristimulus") values (or perhaps more – e.g., see tetrachromacy and pentachromacy). Each of the three values represents the intensity of a particular primary such as red, green or blue, or the coordinate along one axis in a transformed color representation system such as YCbCr. Please see color and color space – but it takes three values to make a color. I've heard of "bpc" as an abbreviation for "bits per channel" or "bits per component" before, which makes sense, but I've never heard of it being called "bits per color", which seems like a difficult concept (especially with chroma subsampling). The bit depth discussed in the article is not bits per color – it is bits per sample or bits per channel or bits per component or bits per color component, but it is not bits per color. —Mulligatawny (talk) 03:41, 12 August 2013 (UTC)

I was concerned about this, too, as bit depths are usually bits per color (mean per primary color component). But in the referenced standards, the bit depths are for luma and chroma components, not colors. And those are differently sampled, in general. So bits per sample, though an unusual term in color systems, seems be reasonably suitable here. Better than bits per color, at least. Dicklyon (talk) 03:51, 12 August 2013 (UTC)

The News on our HEVC decoder on ARM has been removed[edit]


I had submitted a press release on HEVC decoder on ARM in HEVC page under implementations and products,but it seems to be deleted. Could you let me know? Should I send it for review? — Preceding unsigned comment added by (talk) 07:25, 8 July 2014 (UTC)

It was moved to the High Efficiency Video Coding implementations and products article. Only the more notable announcements are kept in this article and there are already several software HEVC decoders for ARM. --GrandDrake (talk) 02:52, 12 July 2014 (UTC)

Legal background, trademarks, patents, blood contracts with the Devil etc.[edit]

I'd appreciate a well-sourced background on licensing, trademark / patent locks, open source legality and other stuff make open source implementors and users' life miserable. I see there an opensource released code but I don't know about it's legal problems or usage restrictions. Maybe someone feels like digging. --grin 15:11, 13 March 2015 (UTC)

as what I read from this article and others related to video codices , you need license for commercial use only e.g some video steaming services like Amazon etc need to pay small charge from there revenue (0.5%) . embedded devices like Blue-ray or any video encoding/decoding hardware needs license to use this technology .
For End users not need to pay anything as this Codec will be embedded with software/hardware they use .--Salem F (talk) 11:39, 4 November 2015 (UTC)
Obviously I don't mean what's already in the article, and by all means no anecdotal evidence. :-) You probably don't see the meaning of the question since "will be embedded" doesn't help for example open source programmers to know who'll sue them next week and why. A detailed background would mention sources to who's the licensor, on what basis, what's allowed and what's not, etc. --grin 13:09, 17 February 2016 (UTC)
My take:
The problem with royalty-bearing formats is, firstly, that putting a price on a software copy is detrimental to no-cost-software ecosystems – it makes such software either unviable or illegal. Note that it doesn't matter how open/free the implementation is; if it implements a patented format, the patent holders can demand whatever. The demand may be a price per copy, as in this case, which is reasonable and bearable for a product sold for money… But not so much otherwise: It was a deal-breaker for Firefox's support for H.264 on platforms without this support, until Cisco graciously offered to pay their licensing costs (see OpenH264). Most Linux distributions ship without out-of-the-box support for H.264, AAC, even MP3, and instead require the user to explicitly enable a "restricted" repository for that, described as "may be illegal in some countries".
Secondly, this is a format war – a collective path dependence tug-of-war that tends toward collective lock-in on a global scale, meaning an eventual end to individual choice. One could therefore hope to standardize on something everyone would be able to adopt eventually (i.e. no glaring interoperability problem), yet we are considering something that seems incompatible with the open/free software ecosystem as we know it. — (talk) 22:50, 13 September 2016 (UTC)
Quote x265 developers[2]: Software decoding/encoding on consumer devices must be royalty free84.214.220.135 (talk) 23:33, 13 September 2016 (UTC)

chroma subsampling[edit]

Hi All, Correct me if I'm wrong, but should the following statement: (supporting higher bit depths and 4:0:0, 4:2:2, and 4:4:4 chroma subsampling formats)

Actually read: (supporting higher bit depths and 4:2:0, 4:2:2, and 4:4:4 chroma subsampling formats)

Pm 1982 (talk) 01:30, 20 April 2015 (UTC)

No, that is not correct. What was added was support for monochrome (4:0:0), not 4:2:0, which was already supported in the first version. Also, it seems a bit strange to refer to 4:4:4 as a chroma subsampling format, since the 4:4:4 format does not subsample the chroma. The standard uses the term "chroma format" or "chroma sampling format", not "chroma subsampling format". I will edit the statement to improve its clarity. Mulligatawny (talk) 18:12, 20 April 2015 (UTC)


  • There are various algorithms for data compression, especially for lossy data compression ones for video/audio data
  • There are various implementations of such, either in software or as some ASIC; in case of software, this software can be compiled and the compiled binary be executed on various CPUs, or GPUs, or DSPs, ...
  • there are various file formats
  • There are various standards (e.g. ISO 216)
  • And then there is a huuge collection of buzzword-bingo like e.g. "video compression standard", "Video coding format", "video container", etc. Why? User:ScotXWt@lk 13:15, 15 May 2015 (UTC)
Whether HEVC can be considered an algorithm gets into the issue of software patents which is covered by several other Wikipedia articles. As for "video container" I couldn't find it in the article but the reason that there is a section on containers is because HEVC can be stored in different containers with a few of them being m2ts, mp4, and mkv. --GrandDrake (talk) 02:15, 27 May 2015 (UTC)

Please help clean this article[edit]

If there's a more wonderful example of what can go wrong in a modern Wiki article, I can't find it (well maybe the H.264/MPEG-4 AVC which is equally terrible). It's filled with jargon that can be easily explained, its terribly disorganized, and it's horribly difficult to edit due to the overuse of inline cites. So moving forward I am going to try to slowly beat the text into shape. To start with:

  • the lede is supposed to be a clear and concise overview of the topic. A reader should be able to stop at the bottom of the lede and understand the basics of the body. Ledes should not introduce terms or topics that are not covered in the body (it's an overview of the body). As such there is a special rule that the lede does not normally need to be cited. This lede consisted of an enormous amount of jargon and history that does not help the reader understand the topic, did not actually summarize the system, and failed to mention at all the problems with licensing. If you don't like the lede as I have changed it, IMPROVE IT, don't just revert it back into the horrible state it used to be. We do not need to have a complete description of every group involved, every detail of the releases, and every acronym in the article, leave that in the body!
  • citations are needed wherever someone might challenge a statement, and/or where the citation provides a singular overview of the topic that the user might want to refer to. This is not the case in this article, where citations are piled on top of citations that already cover the statements being cited. Many of these appear to be stuffing, added simply to make the article look more robust. Moreover, the article is literally filled with the same cite being used over and over in the same paragraph, which is entirely unneeded. I have started the process of moving multi-use cites into a bibliography and removing single-use sites on statements that are already covered. I have also removed some of the many, many examples where the same cite is used multiple times in the same para for no obvious reason, although the amount of work here is enormous.
  • in-line referencing, that is cites placed in the body using <ref></ref> tags should be avoided at all costs. They make the edit text very difficult to read, and especially edit. Our goal should be to produce the same article while making it as easily as possible for future editors to add material. So if you are going to add a citation, please check that it isn't already covered in one of the ones we already have. And if you're going to use that cite more than once, please put the cite tag at the bottom and use SFN to refer to it. This can make the edit text orders of magnitude easier to maintain.

Thank you for reading my rant, I now return you to your regularly scheduled edit wars. Maury Markowitz (talk) 16:01, 2 January 2016 (UTC)

The lede should contain the redirects to this article which include MPEG-H Part 2 (internal name used by the ISO/IEC), H.265 (internal name used by the ITU), and JCT-VC (the joint team that develops HEVC). That is why those terms were in the first paragraph. --GrandDrake (talk) 05:29, 4 January 2016 (UTC)
That's certainly nothing I've seen in the past - to the contrary, it is well established that inlinks can point to specific subsections. But if you feel so strongly about this that's fine, but let me at least re-arrange it so it's not entirely gobblygook - these terms do not help the reader understand the topic and THAT is the primary purpose of the lede. Maury Markowitz (talk) 17:07, 4 January 2016 (UTC)

Coding efficiency: 50% improvement only over the unoptimized x.264 (from 2006) and early reference implementations. In practice its closer to 25%[edit]

I just encoded a movie with handbrake using x265 and was dissapointed to not see a factor 2 in efficiency improvement over x264 with standard settings. After reading I understand that you see those 50% numbers only in comparison with rather old, unoptimized h264 encoders (and reference implementations). The up to date or 2015 versions x265 vs x264 (both one of the best availiable encoders) give a 20-25% improvement!

So maybe one should (additionally) mention the more realistic values - or wait until 265 is further optimized :). — Preceding unsigned comment added by (talk) 10:56, 14 May 2016 (UTC)

Numerous studies have shown a compression efficiency benefit of roughly 50%, including a study done recently by Netflix. Academic studies generally compare the HEVC HM reference encoder to the AVC JM reference encoder. Practical studies often compare x264 to x265. The compression efficiency gain is typically measured with 1080P or higher resolutions (the gain is less for smaller picture sizes), at typical consumer bit rates. The percentage efficiency gain is lower at high bit rates (if you give any codec enough bits, the quality approaches lossless compression). By the way, I founded and run the x265 project. Tvaughan1 (talk) 18:58, 26 May 2017 (UTC)

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