The specifications:. The secret of MPEG-2 is in the compression of highest quality so that the video material can be almost 1 : 1 in source quality edited.
Consequently MPEG-2 established to the broadcast standard. The compression rate is in MPEG-4 not higher than MPEG-2 but sprites can be compressed much better because for the coding mechanism is available more time. Possibly it is possible to change to Wavelets. The script language allows in a few bytes operations like "moving" faster to finish than the digital compressed form of the same operation would do.
For a lag-free video in acceptable quality it is not enough. HOW TO. Active Oldest Votes. So, instead of encoding each frame independently, MPEG-4 and other compression standards only encode the difference between successive frames using motion estimation to find the difference between frames Spatial redundancy takes advantage of the fact that in general the colour spread across images tends to be quite low frequency.
Read this for an explanation with nice pictures For further reading, this book is quite good, if a little heavy on the maths. Improve this answer. Lehane Lehane Sharp edges aren't high-frequency, because they don't repeat. They're actually a sum of every frequency at once, which is why DCT compression and some image resizers will add noise around lines instead of blurring them. The image is broken up into 8x8 or 16x16 pixel blocks, and the DCT is performed on each block.
This is because the DCT performance decreases rapidly for larger images. Since MPEG must be streamed, the decoding must be very fast. It's not totally dissimilar to the techniques used by JPEG. MPEG4 uses a variety of techniques to compress video. Michael Logothetis Michael Logothetis 59 2 2 bronze badges.
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The Overflow Blog. Podcast Explaining the semiconductor shortage, and how it might end. Does ES6 make JavaScript frameworks obsolete? Featured on Meta. Now live: A fully responsive profile. Rows in italic refer to future meetings. Approval of 7 CEs related documents 18 Jan 1. Approval of 3 WDs. Approval of 12 CEs related documents 18 Apr 1. Approval of 2 WDs. Approval of 22 CEs related documents 18 Jul 1.
Approval of 27 CEs related documents 18 Oct 1. The definition of each of these CE documents requires lengthy discussions by involved experts because they describe the experiments that will be carried out by different parties at different locations and how the results will be compared for a decision.
It should not be a surprise if some experts work from Thursday until Friday morning to get documents approved by the Friday plenary. This is the start of a Systems standards that will enable the use of PCC in specific applications, as opposed to being just a data compression specification. The PCC work item is currently seeing the involvement of some 80 experts.
If you think that there were more than experts at the October meeting, you should have a pretty good idea of the complexity of the MPEG machine and the amount of energies poured in by MPEG members. To do this the following is needed: specification of tests, collection of appropriate test material, execution of reference or proprietary software, execution of subjective tests, test analysis and reporting.
Very often, as a standard takes shape, new requirements for new functionalities are added. As a rule MPEG develops reference software for its standards. The reference software has the same normative value as the standard expressed in human language. MPEG also develops conformance tests, supported by test suites, to enable a manufacturer to judge whether its implementation of 1 an encoder produces correct data by feeding them into the reference decoder or 2 a decoder is capable of correctly decoding the test suites.
Finally it may happen that bugs are discovered in a published standard. This is an event to be managed with great attention because industry may already have released some implementations. MPEG is definitely a complex machine because it needs to assess if an idea is useful in the real world, understand if there are technologies that can be used to make a standard supporting that idea, get the technologies, integrate them and develop the standard.
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