MxPEG Software Development Kit
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Why MxPEG?
MxPEG seems to be "just another video codec".
In fact, MxPEG is a video codec. And MxPEG is the name of a
simple audio/video container format.
MxPEG was invented by MOBOTIX in 2000. One practical design
goal was to have an encoder that works on a standard Intel
StrongArm CPU running at 206 MHz, and without any dedicated video
compressing hardware. Other design goals were low latency and high
accuracy. For these reasons, the MPEG family of standards wasn't
considered for implementation into the first and second MOBOTIX
camera generations, M1 and M10/D10.
MxPEG was designed to be closely related to JPEG. Basically, it
should add interframe compression where Motion JPEG only
makes use of JPEG's intraframe compression. This
typically yields a bandwidth reduced by two thirds, compared to
Motion JPEG.
The advantages of the MxPEG codec are:
- uses less computing power than MPEG
- this is particularly true for decoding, too (try to
decode and display 25 MPEG4 streams simultaneously on your
computer...)
- latency < 150 ms
- good still image quality (no motion estimation -- image
quality only dependent on selected JPEG quality)
- the codec implementation in the camera is able to deliver
multiple streams with different frame rates simultaneously,
e.g., for live viewing and for storing. No MPEG encoder can do
that.
- the MxPEG implementation in the camera is able to deliver
lip-synchronous audio interleaved with the video frames
Of course there are application areas where MxPEG might not be
the codec of choice, for one of the following reasons:
- not (yet) a standard format
- currently no UDP/multicast support (TCP/HTTP only)
- no efficient compression if large parts of the image are
changing, e.g., when the camera is mounted on a constantly moving
PTZ head.
- sceneries that change very slowly might make the MxPEG
encoder think they're static and keep the encoder from sending
updated tiles
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