Glossary

1080p is a video resolution of 1920×1080 pixels (1920 wide by 1080 tall) — also called Full HD. The 'p' stands for progressive scan, meaning every frame is rendered as a complete image rather than interlaced. 1080p is the maximum resolution at which TikTok, Instagram, Twitter / X, and Facebook serve video.

AAC (Advanced Audio Coding) is a lossy audio compression codec designed as the successor to MP3. It is the audio format inside almost every MP4 video file served by TikTok, Instagram, YouTube, Facebook, and Twitter, and at the same bitrate it sounds noticeably better than MP3.

Aspect ratio is the proportional relationship between a video's width and height. 16:9 (widescreen) is the standard for YouTube, TVs, and most monitors. 9:16 (vertical) is the standard for TikTok, Instagram Reels, and YouTube Shorts. 1:1 (square) was popular for early Instagram feed posts.

Bitrate is the amount of data used to encode each second of video, measured in kilobits per second (kbps) or megabits per second (Mbps). Higher bitrate means more data per second, which means better visual quality but larger file size. At the same resolution, a higher-bitrate video looks substantially better than a lower-bitrate one.

A CDN (Content Delivery Network) is a globally distributed network of servers that caches static content — videos, images, JavaScript files — close to where users are physically located, so the content loads faster than it would from the origin server. TikTok, Instagram, Twitter, and every other social platform uses CDNs to serve media.

DASH (Dynamic Adaptive Streaming over HTTP), also called MPEG-DASH, is a streaming protocol that splits video and audio into separate files and lets the player request the best quality based on current bandwidth. Reddit, Twitter / X, and Facebook all use DASH for video delivery.

FFmpeg is an open-source command-line library for handling video and audio: it can convert between formats, extract audio, merge video and audio streams, transcode codecs, trim clips, and much more. It is the underlying engine inside almost every video tool on the internet, including online converters and downloaders.

H.264 (also called AVC, Advanced Video Coding) is the most widely used video compression codec on the internet. It compresses raw video into a much smaller file while preserving high visual quality, and it is the codec inside virtually every MP4 file served by TikTok, Instagram, YouTube, Facebook, X / Twitter, and Reddit.

An M3U8 file is a UTF-8 encoded playlist that describes the segments of an HLS (HTTP Live Streaming) video stream. It does not contain video data itself — it lists the URLs of small .ts (Transport Stream) chunks that, when played in order, produce the full video.

MP4 (MPEG-4 Part 14) is a digital container format that holds video, audio, subtitles, and metadata in a single file. It is the dominant video format on the modern internet — TikTok, Instagram, YouTube, X / Twitter, Facebook, and Reddit all serve videos as MP4 internally.

Transcoding is the process of decoding a video file and re-encoding it in a different format, codec, resolution, or bitrate. Unlike remuxing (which just changes the container without touching the audio or video data), transcoding always loses some quality because compression is applied a second time.

A watermark is a translucent logo, username, or text overlay added to a video file that identifies the platform or creator that produced it. On TikTok, the watermark is the bouncing TikTok logo plus the creator's @username; on Instagram Reels, it's a small Instagram logo in the corner.