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Glossary

Transcoding

Also known as: video conversion, re-encoding

When you 'convert' a video from MP4 to WEBM, or change resolution from 1080p to 720p, or switch codec from H.264 to H.265, you're transcoding. The original video is decoded back into raw frames and audio samples, then re-encoded according to the new format's rules. Each pass of compression introduces small artifacts — color banding, blocking in fast motion, smeared detail — that can't be undone.

Downloaders generally avoid transcoding to preserve quality. When DropZap downloads a TikTok or Instagram video, it returns the source MP4 unchanged — same codec, same resolution, same bitrate. The only time DropZap transcodes is when explicit conversion is requested, like turning a video into MP3 audio (which requires decoding the video, extracting the audio track, and re-encoding it as MP3).

The alternative to transcoding is remuxing — putting the same encoded video and audio data into a different container without touching the encoded data itself. For example, an .mp4 file with H.264 + AAC can be remuxed to an .mkv container with no quality loss. FFmpeg does this with the -c copy flag: ffmpeg -i input.mp4 -c copy output.mkv. Whenever you can remux instead of transcode, you should.

Related terms

FFmpeg
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.
MP4
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.
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.
Bitrate
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.