CCTV Video Recording and Storage 3 — Questions and Answers
Question 1: What is the primary advantage of H.265 over H.264 in CCTV storage?
- Higher frame rates
- Approximately 50% reduction in file size at the same quality (Correct answer)
- Wider color gamut support
- Faster playback speed
Correct answer: Approximately 50% reduction in file size at the same quality
H.265 (HEVC) achieves roughly 50% better compression efficiency than H.264, significantly reducing storage requirements.
Question 2: In the context of CCTV, what does 'pre-event buffering' mean?
- Storing footage captured before a trigger event occurs (Correct answer)
- Buffering video in RAM before writing to disk
- Compressing video before transmission
- Pre-scheduling recording windows
Correct answer: Storing footage captured before a trigger event occurs
Pre-event buffering continuously holds a rolling window of footage in memory so that video before a trigger (e.g., motion) is also saved.
Question 3: Which storage topology connects NVRs directly to a dedicated storage network separate from the camera network?
- DAS (Direct Attached Storage)
- SAN (Storage Area Network) (Correct answer)
- NAS (Network Attached Storage)
- Cloud-only storage
Correct answer: SAN (Storage Area Network)
A SAN provides a high-speed dedicated network for storage devices, keeping storage traffic separate from the IP camera data network.
Question 4: What does 'variable bitrate' (VBR) recording mean in CCTV systems?
- The frame rate changes based on motion
- The bitrate adjusts based on scene complexity to optimize storage (Correct answer)
- The resolution scales up during high-activity periods
- The camera alternates between two fixed bitrate settings
Correct answer: The bitrate adjusts based on scene complexity to optimize storage
VBR dynamically adjusts the data rate — using more bits for complex scenes and fewer for static ones — to balance quality and storage efficiency.
Question 5: A CCTV installation requires 90 days of retention for 16 cameras each generating 2 GB/day. What total storage is needed?
- 1,440 GB
- 2,880 GB (Correct answer)
- 720 GB
- 4,320 GB
Correct answer: 2,880 GB
16 cameras × 2 GB/day × 90 days = 2,880 GB of total storage required.
Question 6: What is 'scheduled recording' in a DVR/NVR?
- Recording that is triggered only by audio events
- Recording that runs only during user-defined time windows (Correct answer)
- Recording that archives footage to the cloud on a timer
- Recording that alternates between cameras on a schedule
Correct answer: Recording that runs only during user-defined time windows
Scheduled recording allows administrators to define specific time periods during which the system will record, conserving storage outside those windows.
Question 7: Why is RAID not considered a backup solution for CCTV footage?
- RAID drives are too slow for video playback
- RAID protects against drive failure but not against accidental deletion or site disasters (Correct answer)
- RAID cannot store high-resolution video
- RAID requires proprietary software to access footage
Correct answer: RAID protects against drive failure but not against accidental deletion or site disasters
RAID provides redundancy against hardware failure but all copies reside in the same physical location and are equally vulnerable to deletion, fire, or theft.
CCTV Video Recording and Storage 3
What is the primary advantage of H.265 over H.264 in CCTV storage?