AMV

2007-02-01T03:58:34Z

Chinavasion:

* Extension: amv
* Samples: [http://www.mympxplayer.org/sample-videos-dc7.html] and [http://samples.mplayerhq.hu/amv/]

==AMV video origin and history==
Little is known about the history of the '''AMV''' file format other than it been used by [http://en.wikipedia.org/wiki/Chinese_MP4/MTV_Player '''Chinese-made portable MP3 players'''] and been suposedly created to allow video playback capabilities on inexpensive and low end equipment without increasing the cost of those players with the license royalties and more processor power needed for other more complex format/codec pairs.

==AMV Video File Format==
AMV files contain a [[RIFF]] packed stream of video ([[Talk:AMV|video codec?]]) and [[MP3]] encoded audio.

When playing AMV formats, there is clearly some image de/compression taking place, as can be demonstrated by a simple calculation (see the [[MTV|MTV Video Format]] article). The image compression is, however, low by modern standards (around 4 pixels/byte, compared with over 10 pixels/byte in the [[MPEG-2]] DVD-Video standard). With a resolution of 128 x 96, and a frame rate of 12 fps, a 30 minute file will be around 80 MegaByte in size.

==AMV and MTV encoding/transcoding information and utilities==
* [http://www.s1mp3.org/wiki/index.php/Video_encoding AMV encoding tips]
* [http://www.mympxplayer.org/tools-dc10.html www.mympxplayer.org - MP4 resource site and support forum, with MTV conversion/transcoding tools and utilies, (plus sample downloads)]

==Software players that support AMV and MTV playback==
*Unknown

==Hardware players that support AMV and MTV playback==
[http://en.wikipedia.org/wiki/Chinese_MP4/MTV_Player '''Chinese-made portable MP3 players'''], also known as [http://en.wikipedia.org/wiki/S1_MP3_Player S1 MP3 Players].

==External Links==
*[http://en.wikipedia.org/wiki/Chinese_MP4/MTV_Player "Chinese-made portable MP3 player" article on wikipedia.org]
*[http://en.wikipedia.org/wiki/S1_MP3_Player "S1 MP3 Player" article on wikipedia.org]
* [http://www.mympxplayer.org www.mympxplayer.org - MP4 resource site and support forum, MTV conversion/transcoding tools and utilies, plus sample downloads]
*[http://www.moviecodec.com/topics/7595p1.html MTV Video topic-thread on moviecodec.com forum]
* [http://mp4-player-search-swicki.eurekster.com/ MP4 Player Search - Community powered and driven]
* [http://www.mp4nation.com/software/index.html MP4 Nation Knowledge Base: Support and tips on MP4 Players]
* [http://www.imup2date.co.uk/MP4/ An introduction to MP4 players, what they do, what you can do to them and a review]
* [http://www.s1mp3.org/en/docs_deadrec.php Recovering dead players and other software]
* [http://forum.s1mp3.org/ MP4 Forums on S1MP3.org]
* [http://www.moviecodec.com/topics/7595p3.html MTV Video Forum]
* [http://www.youtube.com/watch?v=us507LedkyY (A very negative) video-review of one of these MP4-Player on Youtube]
* [http://www.chinavasion.com/index.php/cName/mp4-players-2gb-mp4-players/ Chinavasion - China direct wholesaler of MP4 Players using AMV video format]

[[Category:Container Formats]]

NXV

2007-02-01T03:54:25Z

Chinavasion:

* Extension: nxv
* Samples: [http://www.banahogg.com/DIA41.nxv] (see note)

NXV is a container format used by the 2006 MP4 Player Watch manufactured by "Shenzhen Adragon Digitek" (China). The wrist watch is reported to support MP4, WMV and WMA, however this is achieved by first converting the files to the NXV format.

==Container Format==
The format consists of a sequence of 512-bytes packets.

Header packet:

bytes 0-11 ASCIIZ magic ("NXV File")
bytes 12-19 ASCIIZ version ("1.0.0", "3.0.1" or "3.0.2")
byte 20 width (pixels)
byte 21 height (pixels)
byte 22-511 unknown - rand byte?

The a/v sequence commences at byte 512 with an audio packet:

uint curSequence = 0
while !eof
u8[500] audio payload
u8[4] unknown
be32 sequence number
le16 length (bytes)
le16 unknown (pixels == bytes/2?)
if (sequence == curSequence)
curSequence += 1
u8[length] video payload

==Audio Payload==
The audio payload is an [[MP3]] stream, including RIFF WAVE headers.

==Video Payload==
Raw video - be16 in 565 RGB format. If the version is "1.0.0", the video is at full-resolution. If the version is "3.0.1", the video is at quarter-resolution; that is, the video data is 1/4 of the size indicated and is scaled in each direction by two on playback. Version "3.0.2" seems to indicate a different format - likely sixteenth-resolution.

==Notes==
* Supported video resolutions are: 96x64, 96x80, 96x96, 128x96, 128x128, 160x128, 176x128. Despite the reduction in video resolution, the resulting NXV file size exceeds that of the input video file.
* Intermediate files are used by the NxvConverter program to store the audio and video payloads (filename.mp3 and filename.tmp) prior to muxing to the NXV file.
* All NXV files examined so far have one frame per video packet and the packets appear at regular intervals. Low and Mid quality have one frame per four audio packets; High quality has one frame for every two audio packets.
* The content of the sequence and length values in an audio packet not followed by a video packet is unknown - probably nothing.
* Example file is an encoding of public domain footage from [http://www.archive.org/details/movies Internet Archive: Moving Image Archive]

==External Links==
* [http://www.andalong.com/English/product628.htm China Manufacturer of MP4 Player watch, An Long / "Adragon"]
* [http://www.chinavasion.com/product_info.php/pName/watch-mp4-player-2gb-15inch-oled-screen Chinavasion - China wholesaler of MP4 Player watch]
* [http://watch.brando.com.hk/prod_detail.php?prod_id=00100 Brando MP4 Watch Product Page]
* [http://forum.doom9.org/showthread.php?t=119616 Related doom9 thread including NXV software download]
* [http://www.nxdevice.com/ Vendor website]

[[Category:Container Formats]]

MultimediaWiki - User contributions [en]

AMV

NXV