To join multiple segments into one long video without re-encoding, use the FFmpeg concat demuxer [3].
In the context of YouTube's protocol, the code 617 identifies a specific video-only stream variant. According to recent YouTube Format ID documentation, format 617 has the following characteristics: Resolution: 1920x1080 (Full HD). Frame Rate: 60 FPS (Frames Per Second). Codec: VP9 (specifically vp09.00.41.08 ). Container: MP4 (often delivered via M3U8 protocol). Bitrate: Approximately 6443k (~6.4 Mbps). g617.mp4
Because it is a stream, it does not contain audio. When a user downloads a file identifying as "g617," they must also download a separate audio stream (like format 140 or 251) and "mux" them together to create a playable video with sound [17, 26]. 3. Practical Usage with yt-dlp To join multiple segments into one long video