MP4 player
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MP4 players are portable media players developed in the People's Republic of China and surrounding regions. A majority of these players do not support the MPEG-4 video format, and are limited to proprietary formats like AMV and MTV,[1] or require conversion to those particular formats.
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[edit] Chipsets
Fuzhou Rockchip Electronics's video processing Rockchip has been incorporated into many MP4 players, supporting AVI with no B frames in the xvid codec, while MP2 audio compression is used.[2] Some players, like the Onda VX979+, have started to use chipsets from Ingenic, which are capable of supporting RealNetworks's video formats.[3] Also, players with SigmaTel-based technology are compatible with SMV (SigmaTel Video).
[edit] AMV
The image compression algorithm of this format[4] 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.[5]
[edit] 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.[5] 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.
[edit] Instruction manuals
Manuals that are bundled with these players are considered to be inconsistent and are generally difficult for users to comprehend due to their poor translation.[6] Manuals may also refer to features that the particular player model may not possess. And due to the nature of the product, there is usually no contact or website information.
[edit] See also
[edit] References
- ^ Wilson, Mark (2007-12-17). MP4 Watch Strikes Again...No Longer Plays MP4. Gizmodo. Retrieved on 2008-01-09.
- ^ Leading Chinese MP4 IC Design Houses' R&D and Product Strategies Research Report # MIC1324. Electronics.ca Publications.
- ^ Teclast announces the M series. haomp (2007-11-28). Retrieved on 2008-03-18.
- ^ Israelsen, Paul D. (1993-09-21). United States Patent 5247357. Retrieved on 2007-12-07.
- ^ a b voroshil (2007-10-15). AmvDocumentation. Google Code. Retrieved on 2008-04-06.
- ^ 1GB Pastel Pink Mp4-Mp3 Player. Amazon.com. Retrieved on 2008-01-13.
