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Glossary

MP4

Also known as: MPEG-4 Part 14, .mp4 file

MP4 is a "container" format, meaning the .mp4 file itself doesn't define how video and audio are encoded — it just holds those streams together. Inside a typical web MP4 you'll find H.264-encoded video and AAC-encoded audio, the same combination used by every major social platform. The MP4 container also supports H.265 (HEVC) video and Opus audio, but those are less common in social-media contexts because of patent-licensing complexity (H.264) and broader compatibility (AAC).

MP4 became dominant because it strikes the right balance: small file size, high quality, fast streaming start times (the metadata header sits at the start of the file, so playback can begin before the full file is downloaded), and near-universal device support. Every iPhone, Android device, modern browser, and TV plays MP4 natively without plugins.

When you download a video from a social platform using a tool like DropZap, you get the source MP4 file the platform stored on its CDN. The format and quality are identical to what the platform serves to its own app — there is no transcoding step.

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Related terms

H.264
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.
AAC Audio
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.
DASH Streaming
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.