Video Transcoding for Mobile Telephony
2005 Project Report
In the last few years, telecommunication systems are gaining
increasing importance in everyday life. Many new digital multimedia communication
services and devices, such as videomessaging, videoconference, gaming, remote
teaching and digital television, have appeared in the market.
It is needed to adapt the media content to different network characteristics, channel
bandwidth and access terminals in order to enable delivery with acceptable service
quality. Video transcoder's aim is to convey an incoming compressed video bitstream to
the outgoing link without the need of fully decoding and re-encoding (a very time-
and processing-consuming activity).
A typical application of video transcoding process
Video transcoding converts a compressed video bit stream:
- from one format to another format
- from one size to another size (spatial transcoding)
- from a bit rate to another one (quality transcoding)
- from a frame rate to another one (temporal transcoding)
The goal of this project is to develop efficient solutions for achieve an optimal video
quality in real-time video transcoding.
Next (third) generation of mobile telephone systems are based on CDMA radio channel
access technique that adapt dynamically the channel bandwidth according to the number
of users. We investigate new transcoding solutions in order to have a good quality of
the video communications forced to smaller channel bandwidth.
We started with studying MPEG-4 video codec and with implementing two temporal video
transcoding architectures together with new frame skipping policies. Successively we
built an implementation of the same temporal transcoder based on H.263 codec. Moreover,
we done an exaustive testing of all architectures combined with all policies.
Currently, we are studying the new H.264 codec and we try to combine the temporal with
the quality transcoding.
Transcoding in mobile telephony for channel bandwidth reduction
Contacts:
Maurizio Bonuccelli, bonucce at di dot unipi dot it
Francesca Lonetti, francesca dot lonetti at isti dot cnr dot it
Francesca Martelli, francesca dot martelli at isti dot cnr dot it
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