IndigoVision IP cameras and encoders support up to 160kbps, as does their VMS. Monophonic on their two-channel encoders and stereo (2-channel) on their IP cameras and single-channel encoders. Default is 64kbps.
Wow this is the most low-level audio question we've ever received!
I doubt that most manufacturers publish which sample rates they support and some may even downsample it when recording, so unless someone has specific knowledge of the VMS, or you ask the manufacturer, it's going to be hard info to come by.
Also, for those unfamiliar, sample rate is separate from bitrate. It's the number of samples taken in one second, which generally requires higher bitrate, but the two are separate. For reference, 8 KHz is about what old analog phones sound like. 16 KHz is about the clearest voice call quality you'll hear, and 44 KHz is about CD quality.
Thanks for the replies; I will check out IndigoVsion, although an "open" VMS with support for multiple IP camera manufacturers, the ability to integrate our own cameras, and customizable/rebrandable end user UI is preferred.
Our customers require maximum speech intelligibility for discerning the exact words said, including names and other words unfamiliar to the listener, down to a whisper, with minimal distortion. Currently we record uncompressed at 48 KHz for direct lossless export to DVD, using microphones that roll off above 16 KHz, which helps preserve the distinguishing characteristics of some fricative consonants and makes our customers confident that they aren't losing anything.
As we scale from our existing analog cabling solution to IP for greater scalability, we would prefer to go with at least 160kbps AAC so customers don't notice a decrease in quality.
I would call IndigoVision "semi-open". Although their NVR software doesn't directly support other manufacturers' primary streams, they do support ONVIF streams. They also have software that can be installed on a separate server that supports direct streams, called "Camera Gateway" and although their VMS cannot redistribute a single Unicast stream like some VMS', they support "Proxy Servers" for that task.
Yes, that is not the same as other companies' direct support for third party cameras and obviously they would prefer you buy a complete IndigoVision end-to-end solution but they are making strides toward openness. They even recently announced availability of a firmware for their HD IP cameras that will allow them to be used with other VMS' via ONVIF streams - a first for them.
I don't know about other VMS providers... but our VMS Digifort is able to record and playback audio at "any" frequency you through at it. In fact, I expect that any VMS that supports PCM or AAC should be the same...
While G.711 and G.726 are limited to 8KHz frequency and 64kbps (g.711) and 16,24,32,40kbps (g.726), other codecs such as AAC and pure audio (PCM) will support different frequencies.
When transmitting AAC or pure PCM audio over an RTSP connection, the server (your camera, DVR...) is supposed to inform the frequency of the audio it is serving in the SDP Description (In RTSP DESCRIBE command reply), that way the VMS can initialize its audio decoder to handle the proper data...
Likewise, when tranmitting video over RTSP, the frequency is always 90khz... but the audio frequency is variable.
We use Axis P8221 for high quality audio recording in interview rooms using Exacq (AAC 128) and Louroe/Crown microphones. These have balanced phantom power mic inputs. They do requires an additional device license.
[IPVM Note: The Poster is from Genetec]
Genetec supports bidirectional audio from IP cameras and encoders. The level of integration and exact capabilities is different per manufacturer. When it comes to audio, there are many parameters that an IP camera/encoder may support to configure audio. Some of them are, but not limited to, Line Level, Mic Level, Gain, Audio Codec, Sampling Rate, Bit Rage, Volume.
The parameters used for a particular unit depends on what the unit supports, as well as what support is included in the driver. When it comes to codecs, there are 3 main codecs that are currently used by different unit manufacturers and supported by Genetec: G.711, G.726, and AAC. When it comes to Sampling Rates, Genetec has integrated to units that support from 8 KHz up to 44.1 KHz. The codecs and sampling rates supported are dependent on not only the manufacturer of the unit but also the model of the unit. As an example, for Axis units, today, we support the AAC codec and sampling rates up 32 KHz.