Image Processing Reference
In-Depth Information
Digital Video on the Move
Mobile Phone Delivery
Delivering content to mobile phones is technically feasible with third-generation (3G)
mobile devices. These use 3G Partnership Project (3GPP) profiles based on an MPEG-4
derivative using the H.264 codec. At the available bit rates, every transmitted bit must
carry useful data. The consumer or the operator is paying by the packet; thus, a compres-
sion system that wastes packets also wastes money. Customers will not put up with that
for very long.
Bit-Rate Limitations
Bear in mind that the available bandwidths for mobile devices are as low as 64 Kbps.
Reducing the frame rate of the video you encode will allow more bit rate to be retained
for image quality. Keep the clips short. Thirty seconds is plenty. You might find that
a streaming solution is preferred to a downloaded video solution because the hand-
set memory is somewhat limited. Check the network provider specs and also be aware
that not all handsets support downloading content. It may be a 3GPP2 issue anyway,
and not relevant to your customer. Streaming is not the same as progressive download,
which also may or may not be supported. Do plenty of investigative planning and then
lots of testing.
Quality Issues
If you are creating content for this medium, you must use source material of the highest
quality available. Because the compression renders the video down to a very low bit rate,
the codec must deliver the best possible averaging of the image, and it can do this more
effectively if the video is clean to start with.
Ideally, the source should be Motion JPEG, or raw uncompressed video. MPEG-2
or MPEG-1 is fine as long as it is cleanly compressed in the first place, and DV format is
good too.
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