to the ones used by developers to tune their codecs are more competitive. Performance comparison Speed comparison Number of frames per second (FPS) commonly used for compression/decompression speed measurement. The following issues should be considered when estimating probable codec performance differences: Decompression (sometimes compression) frame time uniformity Big differences in this value can cause annoyingly jerky playback. SIMD support by processor and codec E.g., MMX, SSE, SSE2, each of which change CPU performance on some kinds of tasks (often including those with which codecs are concerned). Multi-threading support by processor and codec Sometimes turning on Hyper-threading support (if available on a particular CPU) causes codec speed to decrease. RAM speed generally important for most codec implementations Processor cache size low values sometimes cause serious speed degradation, e.g. for CPUs with low cache such as several of the Intel Celeron series. GPU usage by codec some codecs can drastically increase their performance by taking advantage of GPU resources. So, for example, codec A (being optimized for memory usage i.e., uses less memory) may, on modern computers (which are typically not memory-limited), give slower performance than codec B. Meanwhile, the same pair of codecs may give opposite results if running on an older computer with reduced memory (or cache) resources. Profiles support Modern standards define a wide range of features and require very substantial software or hardware efforts and resources for their implementation. Only selected profiles of a standard are typically supported in any particular product. (This is very common for H.264 implementations for example.) The H.264 standard includes the following seven sets of capabilities, which are referred to as profiles, targeting specific classes of applications: Baseline Profile (BP): Primarily for lower-cost applications with limited computing resources, this profile is used widely in videoconferencing and mobile applications. Main Profile (MP): Originally intended as the mainstream consumer profile for broadcast and storage applications, the importance of this profile faded when the High profile (HiP) was developed for those applications. Extended Profile (XP): Intended as the streaming video profile, this profile has relatively high compression capability and some extra tricks for robustness to data losses and server stream switching. High Profile (HiP): The primary profile for broadcast and disc storage applications, particularly for high-definition television applications. (This is the profile adopted into HD DVD and Blu-ray Disc, for example.) High 10 Profile (Hi10P): Going beyond today's mainstream consumer product capabilities, this profile builds on