From their advanced encoding help file… https://support.google.com/youtube/answer/1722171?hl=en&ref_topic=2888648
Recommended bitrates, codecs, and resolutions, and more
No Edit Lists (or you may lose AV sync)
moov atom at the front of the file (Fast Start)
Audio Codec: AAC-LC
Channels: Stereo or Stereo + 5.1
Sample rate 96khz or 48 khz
Video Codec: H.264
Progressive scan (no interlacing)
2 consecutive B frames
Closed GOP. GOP of half the frame rate.
Variable bitrate. No bitrate limit required, though we offer recommended bit rates below for reference
Color Space: 4.2.0
Frame rates should match the source material. For example, content shot in 24fps should be encoded and uploaded at 24fps. Content recorded at 30fps should be uploaded at 30fps. Content shot in 720p60, should be uploaded at 720p60. Content at 1080i 60, should be deinterlaced, going from 60 interlaced fields per second to 30 progressive frames per second before uploading.
Standard quality uploads Type Video Bitrate Mono Audio Bitrate Stereo Audio Bitrate 5.1 Audio Bitrate
2160p (4k) 35-45 Mbps 128 kbps 384 kbps 512 kbps
1440p (2k) 10 Mbps 128 kbps 384 kbps 512 kbps
1080p 8,000 kbps 128 kbps 384 kbps 512 kbps
720p 5,000 kbps 128 kbps 384 kbps 512 kbps
480p 2,500 kbps 64 kbps 128 kbps 196 kbps
360p 1,000 kbps 64 kbps 128 kbps 196 kbps
High quality uploads for creators with enterprise quality internet connections Type Video Bitrate Mono Audio Bitrate Stereo Audio Bitrate 5.1 Audio Bitrate
1080p 50,000 kbps 128 kbps 384 kbps 512 kbps
720p 30,000 kbps 128 kbps 384 kbps 512 kbps
480p 15,000 kbps 128 kbps 384 kbps 512 kbps
360p 5,000 kbps 128 kbps 384 kbps 512 kbps
YouTube uses 16:9 aspect ratio players. If you are uploading a non-16:9 file, it will be processed and displayed correctly as well, with pillar boxes (black bars on the left and right) or letter boxes (black bars at the top and bottom) provided by the player. If you want to fit the player perfectly, encode at these resolutions:
The YouTube player automatically adds black bars so that videos are displayed correctly without cropping or stretching, no matter the size of the video or the player.
For example, the player will automatically add pillarboxing to 4:3 videos in the new 16:9 widescreen player size. If the player is re-sized (i.e. when embedded on another website), the same process takes place so that 16:9 videos are letterboxed when the player is sized to 4:3. Similarly, anamorphic videos will be automatically letterboxed when shown in either 16:9 or 4:3 sized players. The player can only do this if the native aspect ratio of the video is maintained.
You can adjust the fit of your video in our player after uploading your video by using formatting tags.