IT2032PAContent Management System (CMS) Nitec in Social Media & Web Technology
System Requirements for a Streaming ServerIn this chapter, you will learn: o Identify the hardware requirement for a media server o Identify the software requirement for a media server o Identify the recommended bandwidth for streaming media o Identify the audio and video codec used for streaming media
Requirements• Hardware Requirement – Enough bandwidth to allow access to that media. o Depending on the uses and applications o A media server may require large amounts of RAM, or a powerful, multicore CPU. o A RAID may be used to create a large amount of storage. o TV tuner cards (Digital or Analog)
Requirements• Software Requirement – Enough bandwidth to allow access to that media. o Adobe o Microsoft o Apple
Requirements• Streaming bandwidth and storage o 2.5 Mbit/s or more for streaming movies o 10 Mbit/s or more for HD movies
Requirements• Streaming bandwidth and storage Example: o Bandwidth: 1 hour of video encoded at 300 kbit/s (320 240 pixels window size) (3,600 s 300,000 bit/s) / (8 1024 1024) storage = (108000000) / (8388608) = 128.74 Storage o Storage: on-demand streaming 1000 viewer using using a Unicast protocol 300 kbit/s 1,000 = 300,000 kbit/s = 300 Mbit/s of bandwidth
Exercise• Streaming bandwidth and storage Example: o Bandwidth: 3 hour of video encoded at 300 kbit/s (320 240 pixels window size) (_________ s 300,000 bit/s) / (8 1024 1024) storage = (__________) / (8388608) = ___________ Storage o Storage: on-demand streaming 3500 viewer using using a Unicast protocol 300 kbit/s _________ = __________ kbit/s = _________Mbit/s of bandwidth
Codec, Bitstream, Transport, Control • Media: SWMD Video 1. Audio is compressed: MP3, Vorbis or AAC Video stream is compressed: H.264 or VP8 2. Assembled in a container bitstream such as FLV, WebM, ASF or ISMA 3. The bitstream is delivered (streaming server to a streaming client) using a transport protocol, such as MMS or RTP. 4. Client interacts with the streaming server using a control protocol such as MMS or RTSP
Network Congestion,Bandwidth Spikes and Buffering• Network congestion and other problems are fairly common• To help ameliorate the interruption of the data stream, buffering is implemented.
Network Congestion,Bandwidth Spikes and Buffering• Buffering works by storing a portion of the video locally, and then playing the video by retrieving data from the local buffer.• Buffering can also help encoding videos that contain spikes of high bandwidth. This can occur if something in the video suddenly requires more bandwidth
Audio and Bandwidth• Audio requires bandwidth just as video does.• The higher the quality of the audio, the more bandwidth it will consume. o Media Encoder always use compressed audio. o PCM uncompressed audio, 22.050 kHz, 16 bit mono for instance requires 43 kbps of bandwidth o Lower quality audio such as ACELP.net 8 kHz, mono for example requires only 5 kbps of bandwidth.
CODECs• Codecs are compression technologies with two components; An encoder to compress the file in your studio or office and a decoder to decode the file when played by the remove viewer. o Streaming space - H.264, VP6, Windows Media and Sorenson Spark o DVD and Blu-ray spaces - MPEG-2 H.264 and MPEG-2 are huge in the network and particularly satellite spaces.
Distribution Environments• Windows Media• Flash• QuickTime Make sure that they have the appropriate player installed.
Commonly used Video CODECS• Lossless codecs (FFv1)• MPEG-4 Part 2 codecs (Div X Pro, Xvid)• H.264/MPEG-4 AVC codecs (x264, NERO Digital, QuickTime H.264)• Microsoft codecs (WMV, MS MPEG-4v3)• On2 codecs (VP6, VP6-E, VP6-S, VP7, VP8)
Other Video CODECS• Sorenson 3 used by Apples QuickTime• Sorenson Spark used by Macromedia• RealVideo used/developed by Real Networks• Cinepak early codec used by Apples QuickTime
Commonly used Audio CODECS• Non-compression formats o Linear Pulse Code Modulation (describe as PCM) • Audio Interchange File Format (AIFF, audio container format) • WAV – Microsoft ”WAVE” o Pulse-density modulation (PDM) • Direct Stream Digital (DSD) is standard for Super Audio CD
Commonly used Audio CODECS• Lossless data compression o Apple Lossless Audio Codec (ALAC) • QuickTime o Dolby TrueHD • FFmpeg (decoding only) o Free Lossless Audio Codec (FLAC) • FFmpeg • libFLAC o MPEG-4 Audio Lossless Coding (MPEG-4 ALS) o MPEG-4 ALS reference software o Windows Media Audio 9 Lossless
Commonly used Audio CODECS• General o Adaptive Differential (or Delta) pulse-code modulation (ADPCM) o Adaptive Rate-Distortion Optimised sound codeR (ARDOR) o Adaptive Transform Acoustic Coding (ATRAC, used in MiniDisc devices) o Dolby Digital (A/52, AC3) o MPEG-1 Audio and MPEG-2 Audio
Commonly used Audio CODECS• General o MPEG-4 Audio o FFmpeg (decoding only) o Windows Media Audio (WMA) • Windows Media Encoder • FFmpeg