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Design of Subband Codec for HDTV Transmission
Kazunari IRIE Yasuyuki OKUMURA Naoya SAKURAI Ryozo KISHIMOTO
IEICE TRANSACTIONS on Communications
Publication Date: 1993/11/25
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Communication Terminal and Equipment
video, HDTV, subband, DCT, coding,
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High Definition Television (HDTV) is likely to be one of the major services in the Broadband Integrated Services Digital Network (B-ISDN). The transmission of HDTV signals on digital networks requires the adoption of sophisticated compression techniques to limit the bit-rate requirements and to provide high-quality and cost-effective network services. A flexible coding scheme that supports various bit-rates is needed to support the various services expected which will have different requirements. This paper describes the design of an HDTV codec based on a subband DCT coding algorithm that can encode original 1.2 Gb/s HDTV signals to less than 50Mb/s. A configuration that efficiently bridges HDTV and standard TV signals is also proposed. Computer simulation results show that the degradation caused by the bridging function is insignificant. In the coder, first stage quadrature mirror filters (QMFs) decompose the input signal into two bands in the horizontal direction, while the second stage filters decompose the two bands into four bands in the vertical direction. Adaptive DCT (Discrete Cosine Transform) is adopted for horizontal-low and vertical-low (LL) signal coding. High-band signals are coded by adaptive DPCM and PCM. To maximize bit-rate reduction efficiency, DCT coding is adaptively applied to either the intra-field signals, the inter-field signals, or the motion compensated inter-frame signals. Bi-directional inter-frame prediction is applied to the adaptive DCT coding to improve coding performance at low bit rates. The same prediction mode as for LL signal is applied to adaptive DPCM coding of LH and HL signals. Compatibility is realized by a configuration in which both the TV signal components and the residual signal, derived by subtracting the TV signal from the LL signal, are encoded.