Compatible HDTV coding for broadband ISDN

A compatible digital HDTV (high-definition television) coding scheme is proposed for broadband ISDN (integrated services digital network) applications. This scheme is capable of compressing HDTV for transmission at the H4 access rate of roughly 135 Mb/s with an embedded signal for delivering EQTV (extended quality TV) over a subchannel of 45 Mb/s. Two major processing components are introduced in this system to facilitate compatible coding; one is decimation in the frequency domain and the other is progressive coding. The decimation, performed in the DCT (discrete cosine transform) domain, results in a low pass filtered and decimated version of HDTV. The progressive coding squeezes the decimated signal into the 45 Mb/s subchannel and properly refines it for 135 MB/s HDTV coding. Simulation results show that high quality HDTV can be achieved at 135 Mb/s and that the quality of the embedded 45 Mb/s signal is also very good