Save YouTube Videos as MP4 at the Available Quality

When a selected MP4 needs two tracks, the server fetches those specific format IDs and uses FFmpeg to mux compatible streams into an MP4 file. Stream-copy muxing changes the container without re-encoding the compressed picture or sound, avoiding another generation of quality loss. Playback compatibility still depends on the codecs inside the container: H.264 with AAC is widely supported by browsers, phones, smart TVs, and editing software, while AV1 or VP9 support varies by device. Check the format label before saving, especially when moving a file to older hardware.

MP4 names a container, not a single video codec. Depending on the video, available MP4 tracks may use AVC/H.264, AV1, or another codec, while audio is often offered as AAC in M4A. YTMetadata reads the source format list and shows resolutions that are actually available; it does not invent detail by upscaling a low-resolution source. Some lower-resolution files are progressive and already contain picture and sound. Full HD and higher commonly use separate DASH representations, one for video and one for audio.