wristwatch bands available. Modern MP4 players can play video in a multitude of video formats without the need to pre-convert them or downsize them prior to playing them. Some MP4 Players possess USB ports, to allow users to connect it to a personal computer to sideload files. Some models also have memory card slots to expand the memory of the player instead of storing files in the built-in memory. Chipsets Chipsets and file formats that are particular to some PMPs: Anyka is a chip that's used by many MP4 Players. It supports the same formats as Rockchip. Fuzhou Rockchip Electronics's video processing Rockchip has been incorporated into many MP4 players, supporting AVI with no B frames in MPEG-4 Part 2 (not Part 14), while MP2 audio compression is used. The clip must be padded out, if necessary, to fit the resolution of the display. Any slight deviation from the supported format results in a Format Not Supported error message. Some players, like the Onda VX979+, have started to use chipsets from Ingenic, which are capable of supporting RealNetworks's video formats. Also, players with SigmaTel-based technology are compatible with SMV (SigmaTel Video). AMV The image compression algorithm of this format is inefficient by modern standards (about 4 pixels per byte, compared with over 10 pixels per byte for MPEG-2). There are a fixed range of resolutions (96 × 96 to 208 × 176 pixels) and framerates (12 or 16 frames) available. However it can be used with limited hardware requirements. A 30-minute video would have a filesize of approximately 100 MB at a 160 × 120 resolution. MTV The MTV video format (no relation to the cable network) consists of a 512-byte file header that operates by displaying a series of raw image frames during MP3 playback. During this process, audio frames are passed to the chipset's decoder, while the memory pointer of the display's hardware is adjusted to the next image within the video stream. This method does not require additional hardware for decoding, though it will lead to a higher amount of memory consumption. For that reason, the storage capacity of an MP4 player that uses MTV files is effectively less than that of a player that decompresses files on the fly. Operation Digital sampling is used to convert an audio wave to a sequence of binary numbers that can be stored in a digital format, such as MP3.