Talk:Macroblock

I took out the section on 4:2:0 because it is misleading. 4:2:0 is actually 4:1:1 with the Cb and Cr fields alternating giving a loss of temporal resoloution and macroblocks are more easily described spacially.

I took out "some blocks in macroblock match well, some match poorly" from the cbp description. — Preceding unsigned comment added by 130.149.224.30 (talk) 15:38, 13 February 2012 (UTC)[reply]

Bitstream Representation

The section on Bitstream Representation is kind of redundant and should be removed. The article should describe what kind of information is stored within the macroblock but not give a generic representation of how it could be stored. If someone thinks it is useful (I don't see how but nevermind), then they should give the representation from a well defined standard. Kegon (talk) 14:47, 7 December 2013 (UTC)[reply]

I'm not sure if the section should be kept or removed. It is not redundant, in the sense that it contains information that isn't elsewhere in the article. The given representation looks to be taken from 'FIGURE 9/H.261' on page 10 of the the referenced H.261 standard. The names of the bitstream elements used in the article are somewhat more generic, but not fundamentally different from those in the standard. Using the representation from H.261 makes sense, because the H.261 standard contains all the essential features of motion compensated transform video coding, without the bloat of newer standards (compare section 6.2.5 of H.262/MPEG-2 and section 7.3.5 of H.264/AVC). As an aside, I think that the H.261 standard in general is a very good teaching tool for motion compensated transform video coding. Conquerist (talk) 14:39, 10 December 2013 (UTC)[reply]

"Macroblocking"

This article claims that there is an artefact in block coded images and video called "macroblocking". This mistake seems to derive from a few web pages and forums where the authors were not expert in the subject; and are now being used as citations. The phenomena they are referring to are widely known as "block artefacts" arising from block transform coding of image and video. It's quite possible that other people have discovered this Wikipedia definition and used that when writing articles, thus creating a self perpetuating falsehood. The section on "Macroblocking" should be removed.Kegon (talk) 14:43, 7 December 2013 (UTC)[reply]

Block artifacts is certainly a more correct term, however macroblocking seems to be in more widespread use (10,000 vs. 64,500 Google hits). Still, I agree, a section about block artifacts of all types does not belong into this article. Perhaps it can be integrated into the article Compression artifact, with changes to the last two sentences of the first paragraph. We could leave a hatnote about "macroblocking" on this page. Conquerist (talk) 14:52, 10 December 2013 (UTC)[reply]

Moved the section to Compression artifact. Should probably be integrated into the Image and Video sections of that article. Conquerist (talk) 19:57, 5 February 2014 (UTC)[reply]

A Google search proves that "macroblocking" is the correct term ? What other search terms did you use ? If you could narrow the search to video processing experts I am confident you would find greater than 100:1 in the other direction. Kegon (talk) 22:57, 30 March 2014 (UTC)[reply]

The number of Google hits indicates usage prevalence. WP:COMMONNAME says: "Wikipedia prefers the name that is most commonly used (as determined by its prevalence in reliable English-language sources) as such names will be the most recognizable and the most natural". Conquerist (talk) 01:01, 31 March 2014 (UTC)[reply]

linear block transforms

This is referred in the opening sentence without a link or explanation. Would be great to have some more detail. 50.197.184.177 (talk) 16:10, 10 December 2014 (UTC)[reply]

Well, there are a number of articles that touch on linear block transforms, but there's no article dedicated to them. One way to put it, a linear block transform is a generalization of the discrete cosine transform as it is used in JPEG, but with an arbitrary set of basis functions instead of a set of sampled cosine functions. Two good explanations are in the DCT section of the JEPG article and the multidimensional DCTs section of the DCT article. The lead section here already links to both of these articles which implicitly explain the concept of a linear block transform, but always refer to the DCT specifically and and do not use the term "linear block transform".
Information on linear block transforms could probably be integrated into the transform coding article. Conquerist (talk) 19:40, 10 December 2014 (UTC)[reply]