Multimedia Hardware, Storage and Input/Output Devices
What this domain tests
Device selection and quantitative reasoning: capture quality, display characteristics, optical storage capacity and transfer rates, and interface bandwidth sufficiency for real-time media.
Core rules and concepts
- Capture. Scanners use CCD or CIS sensors; distinguish optical resolution from interpolated dpi, and check bit depth and dynamic range. Cameras pair CCD/CMOS sensors with lens, aperture and ISO; optical zoom changes the image, digital zoom only crops.
- Display. Native resolution, refresh rate, response time, contrast ratio, viewing angle and colour gamut (sRGB, Adobe RGB, DCI-P3) matter more than diagonal size. LCD, OLED and DLP/laser projection differ in black level and burn-in behaviour. Dot pitch and viewing distance govern perceived sharpness.
- Optical storage. CD holds roughly 650–700 MB with 1× = 150 KB/s (~1.2 Mbit/s); DVD single layer holds 4.7 GB with 1× = 1350 KB/s (~11 Mbit/s); Blu-ray single layer holds 25 GB with 1× = 36 Mbit/s. Quoted "52×" speeds are maximum CAV rates, not sustained rates, and access time is distinct from transfer rate.
- Interfaces. USB 2.0 at 480 Mbit/s, USB 3.x in the Gbit/s range, IEEE 1394 (FireWire 400/800) offering guaranteed isochronous bandwidth for DV at 25 Mbit/s, HDMI and SDI for professional video, Thunderbolt for aggregate device bandwidth. Capture cards and GPU hardware encoders (NVENC, Quick Sync) offload real-time compression.
- Flash and magnetic media. SSDs give low-latency random access and suit layered playback; hard disks give cheap sequential throughput; tape remains archival.
Worked example
How much storage does 90 minutes of 25 Mbit/s DV need? 25 Mbit/s × 5400 s = 135,000 Mbit = 16,875 MB ≈ 16.9 GB. Against 4.7 GB per single-layer DVD that is about 3.6 discs, so a dual-layer Blu-ray or a hard disk is the sensible delivery medium. Note that the 1394 interface must sustain 25 Mbit/s continuously - isochronous mode exists precisely to guarantee that.
Traps that cost marks
- Assuming the ×N multiplier is the same across formats; CD 1× = 150 KB/s, DVD 1× = 1350 KB/s, Blu-ray 1× = 36 Mbit/s.
- Comparing a device's burst interface rate with its sustained media rate.
- Accepting interpolated scanner dpi as real optical resolution.
- Forgetting that capture quality is limited by sensor size and lens, not megapixels alone.