UNIT - 5

Introduction to Image and Video Compression ImageCompression, JPEG, MPEG compression techniques Digitizing Audio and Video data representation formats, Compression of Audio and Video files. Comparison of various methods of compression.

Multimedia

Digitizing Audio And Video

Digitizing Video

Quantization

Compression

Audio And Video Compression

Audio Compression

Predictive Encoding

Predictive encoding

Perceptual Encoding

MP3

frequency masking

temporal masking

Video Compression

Joint Photographic Experts Group (JPEG)

Moving Picture Expert Group(MPEG)

Image Compression JPEG

Reading the table

video Compression : MPEG

Spatial Compression

Temporal Compression

I-Frames

intracoded frame(I-Frame)

P-frames Predicted frame(P-Frame)

B-frames

bidirecionial frame(B-Frame)

MPEG

MPEGI

CD-ROM

4.4 Streaming Live Audio/Video

4.5 Real-Time Interactive Audio/Video

characteristic

time relationship

Internet

jitter

figure 29.16 Time Stamp

to prevent jitter we can time Stamp the packets and separate the arrival time from the playback time.

playback buffer

ordering

a playback buffer is required for real-time traffic .

A sequence number on each packet is required for real-time traffic.

real-time traffic need the support of multicasting

a playback buffer is required for real-time traffic A sequence number on each packet is required for real-time traffic real-time traffic need the support of multiplexing multi class teaching

translation

translation means changing the coding of Payload to a lower quality to match the bandwidth of the receiving network

mixing means combining several stream of traffic into one stream

support from transport layer protocol

TCP with all its sophistication is not suitable for interactive multimedia traffic because we can't allow retransmission of packets

udp is more suitable than TCP for interactive traffic however we need the services of RTP another transferred layer protocol to make up for the deficiency of udp

RTP real time transport protocol