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A List of Popular Video Codecs and Formats -2

A list of popular video codecs and the formats they are/were used in:

Motion-JPEG: it is an adaptive JPEG compression way used for static photos in videos. MJPEG encodes each frame at the best speed by varying JPEG and it does not deal with relations between similar frames. Hence it has the superiority that enables people to get access to each frame with no construction of the past and the future frames. In this way, it is still okay to use this codec, such as on portable cameras, as long as the straightforward editing is suitable.

MPEG-1: it’s a codec used in MPEG-1 media files, which is more suitable to be said as a group of codecs. Since the format and the codec of MPEG-1 are mostly inseparable, it is justified to interchange them. MPEG-1 is based on the idea as Cinepak as well as the concept of motion estimation, which means that it is able for each tiny blocks to move around between consistent frames. People can describe or predict so-called P-frames by relating to some of the past frame at a position with a limited range of movement. People can also predict by using both the preceding and the future frames, which makes the file size far smaller than Cinepak.

MPEG-2: actually, MPEG-2 differs little from MPEG-1. There are only some small improvements. However, with MPEG-1 was almost equal to VHS video, MPEG-2 mainly made for high-qualified digital video (How to: MPG to MOV for Mac). In this way, MPEG-2 possesses higher video resolutions and higher bitrates, and it needs permission for commercial applications.

MPEG-4: you may ask why there is MPEG-4 before the presence of MPEG-3. Actually, there was no MPEG-3.at all. The MPEG gives number to its products without any rules, such as the creation of MPEG-7 comes after MPEG-4. Anyhow, MPEG-4 is rather a specification for kinds of codecs than a codec, which means that different supported MPEG-4 codecs are able to be used. It leads to an advantage that as long as a codec is supported MPEG-4, it can be used with any supported MPEG-4 player theoretically. For standard MPEG-4, it contains various parts and its part 2 makes a description of the first MPEG-4 video codec and leads to name “the MPEG-4 codec”. Although MPEG-1 and MPEG-4 share the same basis (How to convert MPEG4 to MOV for Mac), MPEG-4 performs better in compression with its high-level features. Let’s take an example. It no longer simply makes a connection between image parts and different positions as in the before frames. It model and encode small differences between different parts only if they are not too large. In this way, it makes it possible for much more effective color-modeling, huge changes and small differences between frames. At the same time, it also permits people to predict a frame from different related frames rather than from only one. It was Microsoft that firstly made a so-called MPEG-4 codec, however, it made non-standard.

H.264: it is a codec which shares the same developer with MPEG-4 and hence it can also be included in the standard in which actually only its part10 can be called the standard. It has achieved its goal to give excellent performance in whatever bitrate situation. An in-loop deblocking filter and a much larger flexibility supply features to enable it to achieve it. Up until now, it can be defined as the best performing codecs. However, the best performing ability is achieved at the cost of enhanced processing power requirements. At the same time, it still requires license for commercial applications even if it’s a standardized codec. People wrongly take for granted that there is an x264 codec for the open-source library named x264(as an implementation of the H.264 codec) is popularly used.

See more articles: Converting WMV to MP4 in Mac OS X

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