Introduction On Video Transcoding

Introduction to Video Transcoding Of MCLAB Seminar Series By Felix

Content ,[object Object],[object Object],[object Object],[object Object]

Introduction ,[object Object],[object Object],[object Object],[object Object],[object Object]

Introduction ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Introduction ,[object Object],[object Object],[object Object],[object Object]

Introduction ,[object Object],[object Object],[object Object],[object Object],Partial Decode Transcode Partial Encode Input Movie Output Movie Drop away data selectively

MPEG Coding Basics ,[object Object],[object Object],[object Object],[object Object]

MPEG Coding Basics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

MPEG Coding Basics ,[object Object],16 16 = 4 3 2 1 0 5 Y Cr Cb Frame Macroblock 8 8 8 8 8 8

MPEG Coding Basics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

MPEG Coding Basics ,[object Object],X X X X X B X X X P X I Skipped Bidirectional Predictive-coded Backward Predictive-coded Forward Predictive-coded Intra-coded

MPEG Coding Basics ,[object Object],Motion Vector Reference frame Current frame - = Actual MB Ref. MB Prediction Residue

MPEG Coding Basics ,[object Object],DCT Quantization Run Length Coding Huffman Coding

Transcoding Algorithms ,[object Object],[object Object],[object Object],Q 1 -1 Q 2 Input Stream Output Stream

Transcoding Algorithms ,[object Object],[object Object],[object Object],Original: + = After Requantization: Prediction Residue Reference MB Actual MB + =

Transcoding Algorithms ,[object Object]

Transcoding Algorithms ,[object Object],Extracted from: “A Frequency-Domain video Transcoder for Dynamic Bit-Rate Reduction of MPEG-2 Bit Streams”

Transcoding Algorithms ,[object Object],Accumulated error Accumulated error Extracted from: “A Frequency-Domain video Transcoder for Dynamic Bit-Rate Reduction of MPEG-2 Bit Streams”

Transcoding Algorithms ,[object Object],A 1 A 2 A 3 A 0 A ref Current Block h w 8-h 8-w In the reference frame (DCT) In the current frame (DCT) Motion Vector

Transcoding Algorithms ,[object Object],[object Object],[object Object]

Transcoding Algorithms ,[object Object],[object Object],[object Object],[object Object]

Transcoding Algorithms Buffer Frames Reconstruction Downscaling Reconstruction of Motion Vectors Reconstruction of Prediction Residual Reconstruction of macroblocks Original frame downscaled frame General Block Diagram of Spatial Downscaling

Transcoding Algorithms ,[object Object],Intra Coded Backward Predictive Coded Bidirectional Predictive Coded Forward Predictive Coded + ?

Transcoding Algorithms ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Transcoding Algorithms ,[object Object],[object Object],Extracted from: “Adaptive Motion-Vector Resampling for Compressed Video Downscaling” By Bo Shen, Ishwar K. Sethi, and Bhaskaran Vasudev

Transcoding Algorithms ,[object Object],[object Object],[object Object],Extracted from: “Predictive Motion Estimation for Reduced-Resolution Video from High-resolution Compressed Video” By Justy W.C. Wong, Oscar C. Au, Peter H. W. Wong and A. Tourapis

Transcoding Algorithms ,[object Object],[object Object],[object Object],Original DCT Picture IDCT Original Pixel Picture Averaging Every 4 Neighboring pixels Downscaled Pixel Picture DCT Downscaled DCT Picture

Transcoding Algorithms ,[object Object],X S T S T T T X Extracted from: “A fast approximate algorithm for scaling down digital images in the DCT domain” by B. Natarajan and V. Bhaskaran A 1 A 3 A 4 A 2 A s 0 0 0

Transcoding Algorithms ,[object Object],[object Object]

Transcoding Algorithms ,[object Object],? F t F t-1 (Skipped) F t-2

Transcoding Algorithms ,[object Object],=? =? MV t ’ = MV t + MV t-1

Transcoding Algorithms ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Summary ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Introduction On Video Transcoding

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Introduction On Video Transcoding