![]() ![]() 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 bit rate (VBR) and constant bit rate (CBR) creates a trade-off between a consistent quality over all frames, and a more constant bitrate, which is required for some applications. First, all codecs have a bitrate control mechanism which 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. But quality/size ratio of output produced by different implementations of the same specification can vary, too. A codec is not a format, and there can be multiple codecs that implement the same compression specification – 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 for codec (volume discounts, etc.).Supported interfaces (VfW, DirectShow, etc.).Type of license (commercial, free, open source).General software characteristics, for example:.Performance characteristics like 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: ![]()
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