This knowledge base article will summarize the information on how to configure the video device that is used during an online recording using a Nox A1 PSG system.
This document will focus on Axis cameras that Nox Medical recommends for use with our Nox A1 PSG system. Information on what models are recommended and what settings should be used for them can be found here.
Information on how to physically connect a video device can be found here.
1. Add the camera to an online room
When the camera has been connected to the LAN network it will automatically appear in the add device dialog of the Online Room setup. Select the camera and click Add to Room.
Now the camera has been physically added to your room and can be used in a recording.
2. Configure the recording properties
In the Online Room dialog select the video camera and click Edit Device.
For the Axis cameras there are two default streaming protocols available in the software.
- MJPEG: For recording only video
- RTSP: For recording video and audio
Make sure that you select the appropriate protocol depending on if you record video and audio or only video. Note that there will appear some delay if you select the RTSP protocol due to data processing. Click Start Preview and evaluate the delay in seconds and enter the number into the Video delay section. Noxturnal will correct depended on the number when the video is re-opened after the study has been recorded.
3. Select Video Profiles
In Noxturnal there are a few built-in video profiles. They are different depending on if the setup is to record only video or with video and audio and they differ in size and quality.
The table below describes the difference between the video profiles built within the software
CBR = Constant bit rate is an encoding method that keeps the bit rate the same as opposed to VBR = Variable bit rate which varies the bit rate. CBR processes audio faster than VBR due to its fixed bit rate value. The downside to a fixed bit rate is that the files that are produced are not as optimized for quality vs. storage as VBR. For example, if there is quiet section of a music track that doesn't require the full bit rate to produce good quality sound then CBR will still use the same value - thus wasting storage space. The same is true for complex sounds; if the bit rate is too low then the quality will decrease. For the Variable bit Rate the user defines the percentage of signal quality.
The video profiles pick up the resolution that is setup up by the camera. In order to change the settings for the camera the user can open any web browser and access the camera settings by entering the camera IP address. For Axis cameras the default user is: root and password: buffy
The estimated filesize is going to differ between the difference in bit rate, sampling rate and is also depended on the camera resolution. For comparison of file size it is recommended to do some test recordings.
No Video displayed in Noxturnal
Where the fix is to make sure that all profiles and setups for the cameras match. If the streaming protocol is set for MJPEG (only video) you need to make sure that the video profile selected is only recording video. The same applies for if the streaming protocol is set to RTSP (video and audio) and the video profile needs to match the RTSP protocol.
Video and audio is delayed or is lagging
In some cases, if the video and/or audio is lagging it is often due to the fact that the computer hardware does not handle compressing the quality of the data that is being captured by the camera. Therefore it is always recommended if any issues are seen, to lower the camera resolution in order to see if that solves any delays or lagging issues. Those settings are camera specific, are not related to Noxturnal and are accessible through a browser.
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