Audio stream types, Accessing the audio streams – Axis Communications Axis 211A User Manual
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AXIS 210A/211A - Video Streams
rtsp://<IP address>/mpeg4/media.amp
This path is for all supported methods, and the client negotiates with the AXIS 210A/211A
to determine exactly which transport protocol to use.
Audio Stream Types
The stream types for audio are:
• G.711 - International standard for encoding wired-telephone audio. Uses PCM
samples to compress audio where higher signal values are compressed more than
lower 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, this
sets 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 methods
The audio stream can be accessed in the Live View page via Motion JPEG or MPEG-4.
Using Motion JPEG
The basic audio transmission method used in conjunction with Motion JPEG video
streaming is transmission over HTTP. The video and audio streams are not synchronized
when using Motion JPEG, so the streams may be slightly out of sync. The latency in any
stream should be low, but this depends on the network infrastructure.
Using MPEG-4
When using MPEG-4, audio is streamed using the same protocol as the video stream. When
audio is transmitted using MPEG-4, the AXIS 210A/211A sends synchronization
information 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 Streams
In addition to accessing audio in the Live View page using AMC, audio from the AXIS
210A/211A can also be accessed in the following ways:
HTTP API
You can read about accessing audio for the other protocols through the VAPIX Application
Programming Interface (API) at http://www.axis.com/techsup
QuickTime/Windows Media Player
It is possible to use QuickTime and Windows Media Player to listen to the audio stream
using the same methods to access video streams.