Sunday, 20 May 2007

A New Video Coding Standard in China

What's AVS?
“Audio and Video Coding Standard” A second generation source coding standard developed by AVS workgroup of China.

1. Inter prediction( Progressive and Interlaced): P frame and B frame
2. Interpolation: AVS supports to quarter-pel MV precision
3. Intra prediction(Luma and Chroma)
4. Transform coding: Coding scheme-> Transform -> Quantization
5. Entropy coding: Exp-Golomb coding for all syntax elements
6. In-loop deblocking: Determine boundary strength by coded model and apply filter of different strength.

To know more details, you can check the following website.

Power Line Communication

1. High transmission rate
2. No need for extra wire. No need for re-wiring.

Hostile transmission environment (Frequency-selective phenomena)

System review:
The backbone of the proposed system is IDMA.

Introduction to IDMA(Interleave-Division Multiple Access)
IDMA is a new method of digital communication that is very powerful and can approach the Shannon limit. For each user, the input data sequence is first encoded and then permutated. The key principle of IDMA is that the interleavers should be different for different users.

To know more details, please read the following paper.

Monday, 14 May 2007

Multimedia Watermarking

(quoted from Kwangwoon University digital media lab)
Speaker: Bede Liu(Princeton University)
Digital watermark
-Secondary information embedded in media data
-Watermarking and data hiding
-Natural images
-Document: binary images, sketches, maps, Check 21,…
-To render watermarking ineffective
-Legal issues

How to insert watermark
How to extract watermark

Spread spectrum embedding
-Place watermark in perceptually significant spectrum
-Use random vector as wmk to avoid artifacts

-scaling JPEG, dithering, cropping

-Need original unmarked image
-May need to perform registration
-Other attacks

How to embed watermark
-Additive embedding ex spread spectrum
-Forcing a relationship ex odd-even

Data hiding for error concealment
-recovery of blocks lost in transmission
-simple interpolation gives poor image quality

Edge estimation and interpolation
-Edge estimation from surrounding blocks

Error concealment using date hiding
-Need s good neighboring blocks
-Two steps of error concealment estimation edge

Shuffling for binary images
-Uneven distribution of flappable pixels among blocks
-Random shuffling “equalized” distribution

A dilemma
-To prove that a watermark W has been embedded in an image.
-Given inages->block DCT(32x32)->subset X
-Prove existence of W

Monday, 7 May 2007

Digital Life Style

(quoted from

4C: consumer products, car entertainment, communication, computer network

The difference between consumer and PC
What’s the difference when you stay in living room and study room?
You will spend much time to learn how to use Office/PowerPoint/ Outlook.
You won’t spend even a minute to learn how to use the TV remote controller.

Therefore, consumers don’t care about hardware inside but the functions and interface. It should be easy to use.

A fail example-PMP(Portable Media Player)
You can do other activities when you listen to music.
You can download music through internet in 1 minute.
The LCD panel of PMP is too small for use

A successful example-Digital Photo Frame
Put digital photos on the digital photo frame. It’s a simple concept and very useful.

Key feature of DPF -Functions in 2007
1. JPEG/TIFF/GIF/BMP/Raw data/
2. MPEG H.264
3. Speaker inside with audio decode functions
4. WiFi/ Power line network inside with DLNA
5. Support direct connection to Flickr, Picase, Webshots
6. Bluetooth and Digital TV function inside.

Digital home applications
1. DMA(digital media acceptor): Transmit the movies from computer to TV
2. IP STB: video on demand
3. IP TV: Encode cable TV signals and transmit to 3G mobile phone

Key features of digital consumer products
1. Must to have
2. Easy to use
3. Low cost
4. Low noise( without fan)
5. Low power(Especially for portable devices)
6. Internet connection (Nice to have)
7. Wireless (Nice to have)