Although two seemingly disparate solutions, the video doorbell and baby monitor security systems provide similar functionality in terms of transferring video and audio from one location to another and have almost identical requirements in this regard. There a few minor differences but the main ones are in connectivity and the power supplied. A video doorbell can be connected wired or wireless, whereas a baby monitor typically has only a wireless connection. Since a video doorbell is integrated into a home or building's infrastructure, Power-over-Ethernet, 24 V AC or any other offline voltage is provided. At the heart of the system is a low-power embedded processor - DM3xx, OMAP-L13x, or AM35xx. Live video display without video encoding can be implemented with roughly less than 100 mW total system power consumption. Even with full video encoding (needed for compression or storage) less than 400 mW total system power is consumed.
The core subsystem includes:
Processor - Performs the processing and synchronization of video and audio, and controls the user interface.
- Image Processing - The image processing capability of the VPFE (video processing front end) found in the aforementioned processors allows for a lower total system cost as cheaper sensor modules can be used due to the advanced video quality tuning features. The VPFE and display subsystem (also called the video processing back end - VPBE) are sufficient for LCD or TV display. The VPBE can also generate composite video output for analog TVs and has the capability to display a menu during live video for user control.
- Video Encoding - MPEG4 and H.264 compression of video and audio is necessary for these systems in order to reduce data packet transmission - consequently not consuming as much of the available bandwidth. Video compression is also important for storage into a HDD or SD/MMC card. Additionally, H.264 provides smaller compressed video than MPEG4 without reduction in video quality after decompression.
- Networking Stack - Allows the user to transmit data via an Ethernet connection. The DM335 and DM355 both require an external Ethernet MAC and PHY, while all other processors have an on-board MAC.
Audio - A video doorbell / baby monitor requires two audio codecs; one for the capture side and the other for the display. While the DM365 has a built-in mono audio codec, all other processors require external audio codecs for audio input/output. External audio codecs can be connected to any of our embedded processors included in this block diagram via the McBSP port.
Memory - Stores executing code, data/parameters, video and sound. DDR2 memory is typically most used with our video processors. For this, we have specialized memory power devices that provide all the power rails needed for DDR, DDR2, DDR3, and DDR3L memory.
Power Conversion - An AC/DC wall adaptor is used for a baby monitor application whereas for video doorbells an offline home/building power supply is used as it is readily available. Another power option is Power-over-Ethernet (PoE) where a wired Ethernet connection is used.
Optional Equipment – Dependent on the customer's requirements a remote display, a notebook, a digital video recorder, or even a single-board computer with human-machine interface (HMI) may be connected. For a video doorbell displaying an image remotely and having the capability to store the data into a hard disk gives the end user added functionality. Connecting the system to computing platforms further enhances the user experience.
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