Lossless Upload, SMPTE Test
0*WARNING MUTE THE SOUND OR YOU'LL HURT YOUR EARS*
Want to see what google/youtube does to your video?
This 10 second video was uploaded losslessly using huffyuv) directly at 1920x1080
This is a SMPTE color bar test that I assembled using Flash CS4 (I could have used just a still image and generated it in a number of other ways) and generating the Sine and white noise channels in Audacity.
As a still image, the file is 6,220,854 bytes
Compressed as a PNG it is 10,976 bytes
Compressed as a JPG 29,755 bytes
As a Video file in HUFFYUV 1920x1080@60fps 701,754,880 bytes
Uncompressed Video is 497,664,000 Bytes+overhead per second.
Uncompressed audio is 1,764,118 bytes 44100hz 16bit stereo, also part of the AVI upload
The compressed Flash .swf file is 21,998 bytes.
The compressed x264 mp4 video stream is 61,351 bytes.
The compressed AAC audio stream is 193,062 bytes.
The files I got back from Youtube:
1080p 284,195 bytes (29fps vfr) 1920x1080 High Profile level 4 (data 114629 bytes avg 101kbps max 196kbps), AAC LC Sample rate 44100 data 164347 avg 146kps max rate 148kbps
720p 290,286 bytes = (29fps vfr) 1280x720 High Profile 3.1 (data 120,721 bytes avg 107kbps max 175kbps), AAC LC Sample rate 44100 data 164347 avg 146kps max rate 148kbps
360p 200,386 bytes = (29fps vfr) 480x270 Baseline Profile 2.1 (data 31370 avg 25kbps, max 44kbps), AAC LC Sample rate 44100, data 163,801bytes, AVG 145kbps
(The 480p streams are not available in HTML5 video tags)
480p = 854x480 84kbps, 276KB (From Flash Video Info)
This leaves an unanswered question, what preprocessing is Google doing? I've thrown various files at google to try and determine what the optimal bitrate video to pre-compress to, and the only stuff I've been able to verify thus far:
1. Youtube will not compress lower-bitrate AUDIO to higher bit rate audio, That's a GOOD THING.
2. Youtube will not increase the frame rate if the original source is less (eg 24fps), it does however always reduce the frame rate to 30, so no point uploading 60p/60i video *NO LONGER TRUE as of late 2014)
3. Youtube seems to do a pretty good job on animated video
4. Youtube always UPSCALES (horribly I might add) any video smaller than 480x270 to 480x270(16:9) or 480x360 (4:3)
5. If the video falls between two sizes, it never upscales to the larger one, but always downscales to the lower one, this can have some terrible effects.
What I was hoping to learn from this:
- What is the lowest bitrate I can pre-compress video to as not to waste time uploading (like I did with this video), as of now this looks more like a moving target and depends on the input source. I may need to upload a video of completely random noise to determine this.
- Lowest rate that audio can be compressed to, appears to be "148kbps max",