Archive for May, 2010

Approximate Youtube Bitrates

I’ve been wondering what bitrates Youtube produces on files, but they don’t upfront say.

New videos are encoded in eight formats. However, due to bug in Youtube, some 24 fps videos (such as those from film sources) will have duplicate frames inserted to make them 30 fps, causing a very noticeable jitter approximately twice a second.

Format Video Codec Audio Codec Container
37 H.264 1920×1080 24/30 fps AAC 44.1khz Stereo mp4
22 H.264 1280×720 24/30 fps AAC 44.1khz Stereo mp4
35 H.264 854×480 24/30 fps AAC 44.1khz Stereo flv
34 H.264 640×480 24/30 fps AAC 44.1khz Stereo flv
18 H.264, 480×360 24/30 fps AAC 44.1khz Stereo mp4
5 Sorenson Spark, 320×240 24/30 fps MP3 22khz Stereo flv
17 MPEG-4 ASP, 12 fps, black bordered to fit 176×144 frame AAC 22khz Mono mp4
13 H.263+, 15 fps, stretched to full frame 176×144 ignoring source aspect ratio AMR 8khz Mono 3gp

Note: This does not include WebM videos yet as the support is still experimental, and Youtube is not yet encoding videos in 1080p, only 720p (format 45) and 480p (format 43).

Now lets see how a couple high quality videos fair on Youtube.

Format Resolution Video and audio bitrate in kbit/sec
The Dark Knight Trailer 3 1080p, using the Apple version. 2:30 long. H.264, 6ch 48khz AAC audio, 24 fps. Youtube encoded this as a 30 fps video.
Original 1920×816 10518 260
37 1920×816 3427 108.8
22 1280×544 1998 108.8
35 Missing on Youtube

34 640×272 517 95
18 480×204 500 108.5
5 320×136 257 64
17 176×144 55.3 27
13 176×144 55.6 13
Avatar Trailer 1080p, using the Apple version. 3:29 long. H.264, stereo 44.1khz AAC audio, 24 fps.
Original 1920×800 9726 99
37 1920×800 3502 126
22 1280×534 2003 126
35 854×356 806 103.84
34 640×266 554 103.81
18 480×200 486 103.82
5 400×166 255 59
17 176×144 55 28
13 176×144 54 13
Big Buck Bunny 1080p, using the Blender Foundation‘s original version. 9:57 long. Theora, stereo 48khz Vorbis audio, 24 fps.
Original 1920×1080 11902 175
37 1920×1080 3531 125
22 1280×720 2020 125
35 854×480 990 107.9
34 640×360 494 108.02
18 480×270 435 108.03
5 400×226 250 59
17 176×144 55 30
13 176×144 49 12

With these 3 popular HD videos, its easy to tell what sort of bitrate Youtube tries to hit.

Format Approximate bitrate target (video and audio)
37 3.75mbit/sec
22 2.25mbit/sec
35 1.25mbit/sec
34 768kbit/sec
18 768kbit/sec
5 384kbit/sec
17 100kbit/sec
13 75kbit/sec