17AXIS 210A/211A - Video Streamsrtsp:///mpeg4/media.ampThis path is for all supported methods, and the client negotiates with the AXIS 210A/211Ato determine exactly which transport protocol to use.Audio Stream TypesThe stream types for audio are:• G.711 - International standard for encoding wired-telephone audio. Uses PCMsamples to compress audio where higher signal values are compressed more thanlower values. In Axis products, this sets the coding type to μ-law 64 kbit/s.• G.726 - Uses PCM samples to code the difference between samples (ADPCM).Reduces bandwidth without losing too much useful audio. In Axis products, thissets the coded bit rate to 24 or 32 kbit/s.All stream types are ITU-T standards and operate on frequencies up to 4 kHz.Audio transmission methodsThe audio stream can be accessed in the Live View page via Motion JPEG or MPEG-4.Using Motion JPEGThe basic audio transmission method used in conjunction with Motion JPEG videostreaming is transmission over HTTP. The video and audio streams are not synchronizedwhen using Motion JPEG, so the streams may be slightly out of sync. The latency in anystream should be low, but this depends on the network infrastructure.Using MPEG-4When using MPEG-4, audio is streamed using the same protocol as the video stream. Whenaudio is transmitted using MPEG-4, the AXIS 210A/211A sends synchronizationinformation along with the streams to the client performing the synchronization.Note: Audio is streamed from the client to the server over HTTP when using Motion JPEG and MPEG-4.Accessing the Audio StreamsIn addition to accessing audio in the Live View page using AMC, audio from the AXIS210A/211A can also be accessed in the following ways:HTTP APIYou can read about accessing audio for the other protocols through the VAPIX ApplicationProgramming Interface (API) at http://www.axis.com/techsupQuickTime/Windows Media PlayerIt is possible to use QuickTime and Windows Media Player to listen to the audio streamusing the same methods to access video streams.
