#Microsoft mpeg codec software
#Microsoft mpeg codec license

This is concerned with how video is perceived by a viewer, and designates their opinion on a particular video sequence. Press-releases and amateur forums may sometimes select sequences known to favor a particular codec or style of rate-control in reviews. So, in a given long clip, such as a full-length movie, any two codecs may perform quite differently on a particular sequence from the clip, while the codecs may be approximately equal (or the situation reversed) in quality over a wider sequence of frames. Other factors may also come into play.ДЇor a sufficiently long clip, it is possible to select sequences that have suffered little from the compression, and sequences that have suffered heavily, especially if CBR has been used, whereby the quality between frames can vary highly due to different amounts of compression needed to achieve a constant bitrate. Third, quality depends on prefiltrations, which are included on all present-day codecs. Second, some codecs differentiate between different types of frames, such as key frames and non-key frames, differing in their importance to overall visual quality and the extent to which they can be compressed. A difference between variable bitrate (VBR) and constant bitrate (CBR) creates a trade-off between a consistent quality over all frames, on the one hand, and a more constant bitrate, which is required for some applications, on the other. First, all codecs have a bitrate control mechanism that is responsible for determining the bitrate and quality on a per-frame basis. Numerous factors play a role in this variability. Prior to comparing codec video-quality, it is important to understand that every codec can give a varying degree of quality for a given set of frames within a video sequence. Each encoder implements the specification according to its own algorithms and parameters, which means that the compressed output of different codecs will vary, resulting in variations in quality and efficiency between them. The decoder component of a codec that also conforms to the specification recognises each of the mechanisms used, and thus interprets the compressed stream to render it back into raw video for display (although this will not be identical to the raw video input unless the compression was lossless). So long as the encoder component of the codec adheres to the specification it can choose any combination of these methods to apply different parts of the content. But quality/size ratio of output produced by different implementations of the same specification can also vary.Д®ach compression specification defines various mechanisms by which raw video (in essence, a sequence of full-resolution uncompressed digital images) can be reduced in size, from simple bit compression (like Lempel-Ziv-Welch) to psycho-visual and motion summarization, and how the output is stored as a bit stream. A codec is not a format, and there may be multiple codecs that implement the same compression specificationВ вЂ“ for example, MPEG-1 codecs typically do not achieve quality/size ratio comparable to codecs that implement the more modern H.264 specification. The quality the codec can achieve is heavily based on the compression format the codec uses. Price (value for money, volume discounts, etc.).Supported interfaces (VfW, DirectShow, etc.).

#Microsoft mpeg codec license

Type of license (commercial, free, open source).

#Microsoft mpeg codec software

General software characteristicsВ вЂ“ for example:.

Performance characteristics such as compression/decompression speed, supported profiles/options, supported resolutions, supported rate control strategies, etc.

Video quality comparisons can be subjective or objective. Commonly video quality is considered the main characteristic of codec comparisons.

Video quality per bitrate (or range of bitrates).

The following characteristics are compared in video codecs comparisons: