CIF-to-QCIF video bitstream down-conversion in the DCT domain

Digital Video Transcoding

“…The cascaded DCT-domain transcoder (CDDT) [38], shown in Fig. 7, can be used for spatial/temporal resolution downscaling and other coding-parameter changes.…”

A DCT-Domain Video Transcoder for Spatial Resolution Downconversion

“…To overcome the constraints of the SDDT, we propose to use the Cascaded DCTDomain Transcoder (CDDT) architecture which first appeared in [6]. The CDDT can avoid the DCT and IDCT computations required in the pixel-domain architectures as well as preserve the flexibility of changing motion vectors, coding modes as in the CPDT.…”

“…Pixel averaging is the simplest way to achieving the downscaling, which can be implemented using the bilinear interpolation expressed below [6,14].…”

“…To achieve the goal of universal multimedia access (UMA), the video contents need to be adapted to various channel conditions and user equipment capabilities. Spatial resolution reduction [5][6][7][8][9] is one of the key issues for providing UMA in many networked multimedia applications. In realizing transcoders, the computational complexity and picture quality are usually the two most important concerns and need to be traded off to meet various requirements in practical applications.…”

“…It is, however, very computationally intensive for real-time applications, even though the motion-vectors and coding-modes of the incoming bit-stream can be reused for fast processing. [2][3][4][5][6][7][8][9][10][11][14][15]. In [10], a simplified pixel-domain transcoder (SPDT) was proposed to reduce the computational complexity of the cascade transcoder by reusing motion vectors and merging the decoding and encoding process and eliminating the IDCT and MC (Motion Compensation) operations.…”