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An Introduction to H.264/AVC and 3D Video Coding
Outline Video Coding Concepts
basic concept review image coding structure video coding structure
H.264/AVC Introduction history performance comparison
H.264/AVC Coding Tools inter prediction intra prediction transform & quantization de-blocking filter entropy coding
3D Video Coding 3D video format multiview video coding
Summary with Q&A
Video Coding Concept
-basic concept review
-image coding structure
-video coding structure
The Scope of Image and Video Coding Standardization
Only the Syntax and Decoder are standardized:
Images and Video
Needs for Video Compression
Without compression Visual telephony (e.g. CIF @ 15 frames/s):
325 (pels) x 288 (lines) x 15 (farmes/s) x 1.5 bytes = 18.25 Mbit/s
Digital TV (ITU-T 601 4:2:0 @30 frames/s): 720 (pels) x 480 (lines) x 30 (farmes/s) x 1.5 bytes = 124.
4 Mbit/s HDTV (e.g. 1280x720 pels 4:2:0 @ 60 frames/s):
Compression results in lower bit rates Lower transmission and storage cost
RGB vs. YCbCr [1/3]
RGB vs. YCbCr [2/3]
RGB vs. YCbCr [3/3]
Common YCbCr Formats
Subjective View
Block Based Coding [1/2]
Block Based Coding [2/2]
Group of Picture (GOP)
Video Coding Concept
-basic concept review
-image coding structure
-video coding structure
Image Coding Structure
Transform
Quantization
S: 0 1 2 3 4 5 6 7 (3 bits)
Quantization:
Quantization step-size Q=2: S/2
Quantization Levels (Q): 0 0 1 1 2 2 3 3 (2 bits)
Inverse quantization (x2): 0 0 2 2 4 4 6 6
Quantization error: 0 1 0 1 0 1 0 1
Quantization step-size Q=4: S/4
Quantization Levels (Q): 0 0 0 0 1 1 1 1 (2 bits)
Inverse quantization (x4): 0 0 0 0 4 4 4 4
Quantization error: 0 1 2 3 0 1 2 3
Effect of DCT + Quantization
Entropy coding
Video Coding Concept
-basic concept review
-image coding structure
-video coding structure
Temporal Redundancy [1/2]
The amount of data to be coded can be reduced significantly
Standard Video Encoder
Block Based Motion Compensation [1/2]
Algorithms for Motion Estimation
Full Search Guarantee find the global minimum SAD high computational complexity
Fast Search Local minimum SAD Low computational complexity Reduce candidate blocks Reduce matching pixels in candidate blocks
Diamond Search
Video coding structure
H.264/AVC Introduction
-History
-Performance comparison
History
Joint Video Team
MPEG-2 Has Hit A Wall
MPEG-4 in Comparison
H.26L Provides Focus
MPEG-4 “Adopts” H.264
State of the Art Standards
MPEG-2 DVD, DVT, since 1994
MPEG-4 DVR, Digital Still Camera, since 1999 ~1.5x coding gain over MPEG-2 (ASP)
MPEG-4 part 10, AVC (H.264) Mobile video, DVB-H, Blu-ray Disc and etc. 2~3x coding gain over MPEG-2
AVC Profiles
coding tools and profiles
H.264/AVC Introduction
-History
-Performance comparison
Compare to Other Standard
Fair comparisons of H.26L(TML-8.0) versus H.263v3,MPEG-2,and MPEG-4 TML-8.0 at half of the bit rate as MPEG-4 for the same visual fidelity Source from VCEG-N18.doc (Soptember,2001)
Objective evaluation Average improvement of TML-8.0over MPEG-2 (VM-5) of 5.8 dB PSNR
(peak gain 7.2 dB) for equal bandwidths TML-8.0 average gain of 3.1 dB relative to H.263++ (High-Latency
Profile) for equal bandwidths (up to 5.2 dB) Gain of 2.2 dB over MPEG-4 (Advanced Simple Profile) for equal
bandwidths (max. 3.6 dB)
Test Sets
“Streaming” Test: Four QCIF sequences coded at 10 Hz and 15 Hz (Foreman, Container, News,
Tempete) Four CIF sequences coded at 15 Hz and 30 Hz (Bus, Flower, Garden, Mobile a
nd Calendar, and Tempete) With B frame
“Real-Time Conversation” Test: Four QCIF sequences encoded at 10Hz and 15Hz (Akiyo, Foreman, Mother an
d Daughter, and Silent Voice) Four CIF sequences encoded at 15Hz and 30Hz (Carphone, Foreman, Paris, a
nd Sean) Without B frames
Objective evaluation [1/2]
Objective evaluation [2/2]
Subjective evaluation
Example: Sequence Mobile, frame 40
Perceptual Test of H.264/AVC High Profile
Objective Performance of H.264/AVC High Profile
Intra mode performance [1/2]
Average gain of H.264 to JPEG: 5.2 dB (luma) Average gain of H.264 to JPEG2000: 1.12 dB (luma) Average gain of Motion JPEG2000 to H.264: 1.42 dB (chroma) The smaller the bit rate, the higher the gain of H.264
Intra mode performance [2/2]
Intra mode performance [chroma]
Intra mode performance [FRExt]
a set of 8 photographic monochrome test images with resolutions from 512x512 up to 2048x3072 samples
Average gain of H.264/AVC HP to JPEG2000: 0.5 dB over the entire test image set and all bit-rates
JPEG2000 vs. H.264 Intra
H.264/AVC Coding Tools
-Inter prediction
-Intra prediction
-Transform and Quantization
-De-blocking Filter
-Entropy Coding
Basic Coding Structure
Standard Tools Comparison
Motion Compensation
Macro Block Partitions
Example – Frame 1
Example – Frame 2
Example – Residual [no MC]
Example – Residual [16x16]
Example – Residual [8x8]
Example – Residual [4x4]
Example of Variable Block Sizes
Large block means Less bits for MVs More bits on residuals
Small block means More bits for MVs Less bits on residuals
Summary
Key Features Enhances motion compensation Small blocks for transform coding De-blocking filter
50% bit rate saving against any other standards, by Better prediction More computation More memory
Video coding layer is still based on hybrid video coding algorithm, buy with important differences