Video Streaming - 4.ppt
Transcript of Video Streaming - 4.ppt
Video Streaming
© Nanda Ganesan, Ph.D.
Video Streaming
• Video Streaming Objective• Streaming Advantages• Video Streaming Architecture• Compression and Decompression-codec• MPEG 1-4 Introduction• Major Products and Features
Comparison
Video Streaming Objective
• The object is to overcome the negative effects of physical distance and network technology limitation.
Streaming Advantages
• Reduce setup time• Reduction in client storage requirement• Video can be viewed in real time • Transmission signals over low
bandwidth facilities
Video Streaming Architecture
• Content Creation/Capture• Content Management• Content Formatting (Compression)• Delivery• Distribution• Presentation (Viewing)• View Control
Video Capture
• Converting analog to video signals– A special video capture card to
convert the analog signals to digital form and compresses the data.
– Also digital video devices that can capture images and transfer to a computer
Content Management
• Critical in video server• The purpose including create, collect,
catalog, organize, store, and access to massive multimedia information database
Video Input Formats
• AVI• ActiveMovie• Cinepak• Indeo• motion-JPEG
• MPEG• QuickTime• RealVideo• Video for
Windows• XGA
Video FormatsAVI & ASF
• Developed by Microsoft• AVI (Audio Video Interleaved)
- limited to 320x240 resolution- 30 frames per second
• ASF (Advanced Streaming Format)- Has been submitted to ISO for standardization- Expected to replace AVI format
Standard Window Size
• 320X240• 640X480
Frame Rates
• 4-6 fps– Absolute minimum for video
conferencing
• 11-14 fps – The norm for video conferencing
• 30 fps– Full motion video
Codec(Compressor/Decompressor)
• Coding techniques to compress video data
• The newest codec change their sampling rate as they run
• Choice of codec is the biggest factor to determine the bandwidth needed to connect the server and receive content
• Many of the codecs follow international standards
Content Compression
• MPEG (A working group of ISO)- The most common standard for video
compression and file formats- Generally produce better quality video than other
formats- High compression rate- MPEG1, MPEG2, MPEG3 and MPEG4
MPEG-1
• MPEG-1 was designed for coding progressive video at a transmission rate of about 1.5 million bits per second.
• It was designed specifically for Video-CD and CD-i media.
• MPEG-1 audio layer-3 (MP3) has also evolved from early MPEG work.
MPEG-2
• MPEG-2 was designed for coding interlaced images at transmission rates above 4 million bits per second.
• MPEG-2 is used for digital TV broadcast and
DVD.
• An MPEG-2 player can handle MPEG-1 data as well.
MPEG-3
• A proposed MPEG-3 standard, intended for High Definition TV (HDTV), was merged with the MPEG-2 standard when it became apparent that the MPEG-2 standard met the HDTV requirements.
MPEG-4
• An MPEG-4 standard is in the final stages of development and release.
• It is a much more ambitious standard and addresses speech and video synthesis, fractal geometry, computer visualization, and an artificial intelligence (AI) approach to reconstructing images.
Video Streaming Standards
• H.261• H.263• MPEG1• MPEG2• MPEG4
H.261
• H.261 is use for teleconferencing applications and is intended for carrying video over ISDN.
• H.261 needs substantially less CPU power for real-time encoding than MPEG.
• H.261 uses constant-bit-rate encoding.
H.263
• H.263 is design for low bitrate communication.
• H.263 expected to be use for wide range of bitrate and expected to replace H.261.
• H.263 supports 5 resolutions, able to compete with MPEG standards.
TCP Transmission Control Protocol
• Protocol used for reliable document transfer
• HTTP (Hypertext Transfer Protocol) uses TCP as the protocol for reliable document transfer.
• Unsuitable for video and audio because: • Imposes flow control• Unnecessary Message delivery
UDP User Datagram Protocol
• UDP is the alternative to TCP. • UDP forsakes TCP's error
correction and allows packets to drop out if they're late or damaged.
• Access Problems (firewalls).
Some Real-Time Transmission Related Protocols
• RTP• VDP• RTSP• RSVP
Major Products
• Microsoft Windows Media Technologieshttp://www.microsoft.com/windows/windowsmedia/
• RealSystem G2 http://www.realnetwork.com
ComparisonWMT –vs- RealSystem G2
• Head to head comparisonFeature Comparison
• More Information http://www.microsoft.com/windows/windowsmedia/
ComparisonWMT –vs- RealSystem G2
• Cost Analysis- Prepared by Approach, Inc.,
• Key findings - Both streaming products results in positive
returns on investment - Microsoft solution is more economical than the
RealNetwork solution• Download in Word format
Audio Streaming Architecture
• Creating Audio File• Demonstration of Streaming Software• Demo of Streaming Process
– Windows Media Encoder – RealProducer 7 Basic
• Play the Audio File