Which digital tool is responsible for compressing and decompressing both video and audio streams?

• A. Container
• B. Encoder
• C. Codec
• D. Bitrate

Answer: (C)

The main idea is that a codec provides both the encoding (compressing) and decoding (decompressing) paths for media streams. A codec includes the algorithms that turn raw video or audio into a compact bitstream, and the corresponding decoding process that expands it back for playback. This dual capability is why it’s the right answer: it handles the complete cycle of compression and restoration across both video and audio.

A container, by contrast, simply wraps the encoded streams and their metadata; it doesn’t perform compression or decompression. Bitrate is a measurement of data flow, not a tool. An encoder does the compression part, but without the matching decode capability, it can’t be played back; the codec encompasses both sides of that process, ensuring the compressed data can be properly decoded. For example, video can be encoded with a codec like H.264 and audio with a codec like AAC, and a compatible decoder is needed to reconstruct the originals during playback.