Mp4: 399

: The standout feature of 399 is its use of the AV1 codec . Compared to older formats like 137 (AVC/H.264), Format 399 can offer similar or even better visual quality at significantly lower bitrates—sometimes reducing file size by 30-50% .

For users who frequently download or archive YouTube content using tools like yt-dlp , Format 399 is often considered the choice for modern video storage. 399 mp4

Users often debate whether to prioritize this format over others when archiving content. : The standout feature of 399 is its use of the AV1 codec

“it visually has the same quality as format 616 (premium) but some videos don't have format 248, so, I don't want to specify a format, just say: "Get the Best Video format available"” Reddit · r/youtubedl · 2 years ago 399 mp4