An adaptive rate control algorithm for video coding over personal digital assistants (PDA)

With the recent development of third-generation communication technologies, encoding live video using a PDA and sharing it among friends has become a reality. However, the embedded processor inside a PDA is still not powerful enough and there are two major hurdles to overcome: (1) video coding needs to meet the rigorous constraint of the available computation capacity of a PDA; (2) In a PDA the computing power allocated to video coding may vary drastically (in bursts). In this paper, a new adaptive rate control algorithm is proposed for video coding over a PDA. This adaptive rate control scheme takes into account the time constraint of a PDA, and its bit allocation depends not only on the available data bits, but more importantly, on the available coding time. Experimental results show that, compared to the existing rate control scheme, the new algorithm can always achieve the maximum frame rate, maximize the utilization of the available bandwidth and computing power, increase the average PSNR, and improve the subjective perceptual quality of the reconstructed video.