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.

FormatVideo CodecAudio CodecContainer
37H.264 1920×1080 24/30 fpsAAC 44.1khz Stereomp4
22H.264 1280×720 24/30 fpsAAC 44.1khz Stereomp4
35H.264 854×480 24/30 fpsAAC 44.1khz Stereoflv
34H.264 640×480 24/30 fpsAAC 44.1khz Stereoflv
18H.264, 480×360 24/30 fpsAAC 44.1khz Stereomp4
5Sorenson Spark, 320×240 24/30 fpsMP3 22khz Stereoflv
17MPEG-4 ASP, 12 fps, black bordered to fit 176×144 frameAAC 22khz Monomp4
13H.263+, 15 fps, stretched to full frame 176×144 ignoring source aspect ratioAMR 8khz Mono3gp

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.

FormatResolutionVideo 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.
Original1920×81610518260
371920×8163427108.8
221280×5441998108.8
35Missing on Youtube

34640×27251795
18480×204500108.5
5320×13625764
17176×14455.327
13176×14455.613
Avatar Trailer 1080p, using the Apple version. 3:29 long. H.264, stereo 44.1khz AAC audio, 24 fps.
Original1920×800972699
371920×8003502126
221280×5342003126
35854×356806103.84
34640×266554103.81
18480×200486103.82
5400×16625559
17176×1445528
13176×1445413
Big Buck Bunny 1080p, using the Blender Foundation‘s original version. 9:57 long. Theora, stereo 48khz Vorbis audio, 24 fps.
Original1920×108011902175
371920×10803531125
221280×7202020125
35854×480990107.9
34640×360494108.02
18480×270435108.03
5400×22625059
17176×1445530
13176×1444912

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

FormatApproximate bitrate target (video and audio)
373.75mbit/sec
222.25mbit/sec
351.25mbit/sec
34768kbit/sec
18768kbit/sec
5384kbit/sec
17100kbit/sec
1375kbit/sec