Three perspectives to consider to select the best video codec
Codec
In this article, as basic knowledge about
codecs: -A codec is a program that encodes (encodes) / decodes (decodes) video data and
Audio.
-Even if the file format is the same, different codecs are different.-Al
play a video,
I explained that the codec used at the time of encoding is also required for the recipient’s viewing environment, but in this article, “compression rate” and “compression rate” are described as “three viewpoints that need to be suppressed to be able to select the optimal video codec. ” I will explain about “standardization” and “display goal”.
Viewpoint 1: Compression Rate | Make it easy to distribute and distribute high-quality online videos
A film expresses movement through a collection of continuous images and, if it is not compressed, the amount of data will be enormous. Therefore, compression technology has been developed to efficiently record and save video data. Compression technology is one of the hearts of codec development. By using compression technology, it is possible to record a large amount of information, such as moving images with a large amount of data, to achieve higher image quality even with the same capacity, and reduce the amount of data to facilitate distribution and distribution. Therefore, “compression rate” is an important point of view when selecting a codec.
■ Two compression methods, “lossy compression” and “lossless compression”
There are two types of data compression methods: “lossy compression”, which reduces the weight of the data by thinning it within a range that does not affect the eyes, and “lossless compression”, which returns the original amount of data. when unzipped without thinning the data. Since the amount of data is very large in “uncompressed”, which does not compress the data at all, compressed data is often used when handling moving images. Lossy compression codecs are often used for video distribution, especially MPEG-4 AVC and WebM for Youtube.
■ High compression rate codec
For example, since the birth of MPEG-1 in 1993, there have been “MPEG series” such as MPEG-2 (1995) and MPEG-4 AVC (2003). MPEG-4 AVC is said to have approximately twice the compression ratio of MPEG-2. In other words, the standard for DVD video is set at approximately 8 Mbps for MPEG-2, but in terms of calculation, if compressed with MPEG-4 AVC, the same image quality can be obtained at approximately 4 Mbps. Double of compression rate means that the file capacity will be cut in half when video is delivered with the same image quality, and the communication bandwidth at the time of delivery will also be cut in half.
By improving compression efficiency, even with the same image quality, a small amount of data can be used.
The load on the video distribution server can be reduced and the server risk minimal and display lag can be
reduced.-Avoid close communication lines and provide information to viewers.
the
advantages of easier delivery and higher image quality of videos.
The following [Demo 1] is compressed using the MPEG-2 codec on the left and the MPEG-4 AVC codec on the right at the same bit rate, but the difference in image quality is clear.
