Video and Audio Streaming with Flash and Open Source Tools.pdfVIP

Video and Audio Streaming with Flash and Open Source Tools ? 2005 Klaus Rechert Flash has always been developed and used for multimedia purposes, but until version 6 the possibilities for audio streaming were limited and also there was no video support. With Version 6 and 7 Macromedia introduced video support and a new file format to support various ways of streaming. This article covers only a streaming variant called progressive download which does not need server support. True streaming support is available with Macromedias non-free Flash Communication Server (FCS). FLV Streams Streaming is build upon a new file format called FLV, which separates the streamable content and the flash movie. The result is a very compact flash movie acting as a multimedia player and a storage for streamable content from which the flash movie loads a stream on demand. A single FLV stream contains at most one audio stream and at most one video stream. Flash supports uncompressed sound and various compressed formats like MP3 and ADPCM as well as the proprietary Nellymoser audio codec. With flash version 6 Macromedia also introduced video support for flash. In version 6 only the Sorenson H.263 video codec was supported which is a slightly modified version of the open H.263 standard. The latest flash version 7 introduced a second video format Screen Video, which is a simple, loss less video format, especially developed for screen capturing. Converting and Creating Content One method for creating FLV streams is converting existing audio and video content with FFmpeg []. FFmpeg is a mature and very excellent software project for converting audio and video from and to various formats. Converting a video can be simply done with ffmpeg -i infile.[avi|mpeg] stream.flv FFmpeg uses the Sorenson H.263 video format for encoding video data. There is no support for the Screen Video format at this time. While the Screen Video format is mainly useful for screen capturin