The name MP4 player is a marketing term for inexpensive portable media players, usually from little known or generic device manufacturers. The name itself is a misnomer, since most MP4 players are incompatible with the MPEG-4 Part 14 or the .mp4 container format. Instead, the term refers to their ability to play more file types than just MP3. In this sense, in some markets like Brazil, any new function added to a given media player is followed by an increase in the number, for example an MP5 or MP12 Player, despite there being no corresponding MPEG-5 standard (as of 2010[update], the current standard, still being developed, is MPEG-4).
These players can play video in a multitude of video formats without the need to preconvert them or downsize them prior to playing them. Some MP4 Players possess USB ports in order for the users to connect it to a PC. Some have memory cards to expand the memory of the player instead of storing files in the built-in memory.
Some MP4 players include a FM transmitter, as Lexar LDP-600FB.
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).
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 / DVD video). There are a fixed range of resolutions (96 × 96 to 208 × 176 pixels) and frame-rates (12 or 16 frame/s) available. A 30-minute video would have a filesize of approximately 100 MB at a 160 × 120 resolution.
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 is effectively less than that of a player that decompresses files on the fly.
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