libavformat-dev - 7:4.1.9-0+deb10u1 main

FFmpeg is the leading multimedia framework, able to decode, encode, transcode,
mux, demux, stream, filter and play pretty much anything that humans and
machines have created. It supports the most obscure ancient formats up to the
cutting edge.
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This library provides a generic framework for multiplexing and demultiplexing
(muxing and demuxing) audio, video and subtitle streams. It encompasses
multiple muxers and demuxers for multimedia container formats. It also
supports several input and output protocols to access a media resource.
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This package contains the development files.