CCTV Video Recording and Storage 4 — Questions and Answers
Question 1: What is the function of a 'watchdog' feature in CCTV recorders?
- To monitor camera lens cleanliness
- To automatically reboot the recorder if it becomes unresponsive (Correct answer)
- To alert security staff when motion is detected
- To limit recording bandwidth during peak hours
Correct answer: To automatically reboot the recorder if it becomes unresponsive
A watchdog timer detects system hangs and automatically restarts the recorder to restore normal operation without manual intervention.
Question 2: In CCTV, what does 'IPS' stand for in the context of recording speed?
- Images Per Second (Correct answer)
- Input Processing Speed
- Internal Playback Standard
- Image Pixel Size
Correct answer: Images Per Second
IPS (Images Per Second) is used with DVRs to indicate how many video frames per second the system can record across all connected cameras.
Question 3: Which format is typically used for exporting CCTV evidence clips for law enforcement?
- Proprietary encrypted format with a bundled player (Correct answer)
- Raw camera sensor data
- Uncompressed BMP image sequences
- Only cloud-shared links
Correct answer: Proprietary encrypted format with a bundled player
Many DVR/NVR manufacturers export clips in a proprietary encrypted format bundled with a standalone player to preserve chain of custody and prevent tampering.
Question 4: What is the effect of lowering the recording frame rate from 30 fps to 15 fps?
- Doubles the storage requirement
- Reduces storage requirement by approximately 50% (Correct answer)
- Improves video resolution
- Increases the bitrate automatically
Correct answer: Reduces storage requirement by approximately 50%
Halving the frame rate roughly halves the number of frames recorded per unit time, reducing storage needs by approximately 50%.
Question 5: What type of hard drive is specifically designed and recommended for continuous CCTV recording workloads?
- Desktop-class consumer drives
- Surveillance-grade drives (e.g., WD Purple, Seagate SkyHawk) (Correct answer)
- Server enterprise SAS drives only
- Solid-state drives (SSD) exclusively
Correct answer: Surveillance-grade drives (e.g., WD Purple, Seagate SkyHawk)
Surveillance-grade drives are optimized for 24/7 write-heavy workloads, simultaneous multi-stream recording, and high drive temperatures common in NVR enclosures.
Question 6: What does 'dual-stream' recording mean in an IP camera system?
- Recording two separate audio channels simultaneously
- Transmitting a high-resolution stream for storage and a low-resolution stream for live view (Correct answer)
- Using two NVRs to record the same camera simultaneously
- Splitting the camera feed between two monitors
Correct answer: Transmitting a high-resolution stream for storage and a low-resolution stream for live view
Dual-stream allows the camera to send a high-quality stream to the NVR for storage while delivering a lower-resolution stream to conserve bandwidth for remote viewing.
Question 7: What is 'edge recording' in a CCTV system?
- Recording video directly on the camera's built-in SD card or storage (Correct answer)
- Recording only the edges of the video frame for motion detection
- Storing footage on a server located at the network edge
- Using edge compression before sending to the DVR
Correct answer: Recording video directly on the camera's built-in SD card or storage
Edge recording stores video locally on the camera itself (typically a microSD card), providing a backup if the network or NVR fails.
CCTV Video Recording and Storage 4
What is the function of a 'watchdog' feature in CCTV recorders?