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 Formats AVI & 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 Technologies http://www.microsoft.com/windows/window smedia/ • RealSystem G2 http://www.realnetwork.com Comparison WMT –vs- RealSystem G2 • Head to head comparison Feature Comparison • More Information http://www.microsoft.com/windows/windo wsmedia/ Comparison WMT –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