Video makes a lot of sense when done on a flip book, zoetrope, or an filmstrip projector, but the various digital video processes and jargon out there maybe confusing to a beginner hence I am writing this short post that can act as a checklist for understanding digital video for complete beginners.

Table of Contents

The Video File

Codec: short for coding/decoding, it is the software library or hardware responsible for encoding (and compressing) the video data. Ex - H.264 (AVC), H.265 (HEVC), VP9, AV1.

Container: aka file format. Clubs together other related data such as audio tracks and subtitles. Ex - Matroska (.mkv), MP4 container.

Video Quality Parameters

Resolution: te number of pixels in each dimension (width x height).

720p (HD)       - 1280 x 720 pixels
1080p (Full HD) - 1920 x 1080 pixels
4K (UHD)        - 3840 x 2160 pixels
8K              - 7680 x 4320 pixels

Frame Rate (FPS): the number of frames displayed per second. Common frame rates are 24, 30, 60, and 120 FPS.

Bitrate: the amount of data processed per unit of time, typically measured in Mbps (megabits per second). More bitrate video consumes bandwidth.

Color Depth: the number of bits used to represent the color of a single pixel. Common depths are 8-bit, 10-bit, and 12-bit.

Color Space: the range of colors that can be represented.

sRGB      - Standard color space for web and consumer devices
Rec. 709  - Standard for HDTV
Rec. 2020 - Standard for UHDTV and HDR

Dynamic Range: the range between the darkest and brightest parts of the image. High Dynamic Range (HDR) content can display more detail in shadows and highlights.

Compression and Codec: Compression reduces file size and bandwidth requirements. More efficient codecs like H.265 (HEVC) and AV1 provide better quality at lower bitrates compared to older codecs like H.264.

Chroma Subsampling: a method of compressing video by reducing the color information (chroma) in relation to the brightness information (luma). Formats like 4:4:4 (no subsampling) offer the best color quality, while 4:2:0 (common in streaming) reduces color data significantly, affecting color fidelity.

Display Quality Parameters

Commonly understood ones are: size, resolution, aspect ratio, refresh rate, color space, brightness, response time, contrast ratio, viewing angles, HDR support.

Apart from these, the panel type plays a very important role in the overall quality of the display.

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LCD
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IPS (In-Plane Switching) - Good color accuracy and viewing angles.
TN (Twisted Nematic)     - Fast response times and high refresh rates, but poorer color and viewing angles.
VA (Vertical Alignment)  - High contrast ratios, decent color, and viewing angles.

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LED
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OLED (Organic Light-Emitting Diode): Excellent contrast, true blacks, good color accuracy, and wide viewing angles, but potential for burn-in (rare).

Playback Quality Parameters

During playback, a video can be processed as well.

Frame Interpolation: creates additional frames by estimating the motion between original frames, resulting in a higher effective frame rate. Can sometimes introduce visual artifacts, such as ghosting, halo effects, or unnatural motion.

Deinterlacing: Converts interlaced video (common in older broadcasts) to progressive scan format. Reduces flicker and artifacts, providing a clearer and more stable image.

Apart from the above, other parameters that can be modified during playback are resolution (upscale/downscale), frame rate conversion, dynamic range adjustment, color space conversion, de-noise and other filters.

Artifacts: unwanted visual anomalies that can degrade the quality of the video. These artifacts can arise from various sources such as compression, encoding, transmission errors, or poor video processing.

References