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Youtube Processing creating artifacts in shadows and midtones... only

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Harold Batista
Youtube Processing creating artifacts in shadows and midtones... only
on Sep 3, 2015 at 3:16:15 am

I am having difficulty figuring why Youtube's processing is only creating artifacts in the shadows and mid-tones of a video I'm uploading.
Especially confusing since the video is shot in super slow motion and has a very homogeneous tonal range. Scenes that are brightly lit are sharp without distortion. Its just these low lit scenes that have problems.

Example 1 from desktop screen grab:

Example 1 from youtube screen grab:

Example 2 from desktop screen grab:

Example 2 from youtube screen grab:


As you can see, the edge of the cheek on the right is fine and the strands of hair as well. But the cheek in shadow has many block artifacts

Compression Details:
General
Complete name : /Users/D1BU/Desktop/HB_test.mov
Format : MPEG-4
Format profile : QuickTime
Codec ID : qt
File size : 1.29 GiB
Duration : 4mn 12s
Overall bit rate : 43.9 Mbps
Encoded date : UTC 2015-09-03 01:20:58
Tagged date : UTC 2015-09-03 01:27:47
Writing library : Apple QuickTime
Media/UUID : 9CFD1853-8656-4DEA-8669-78C0EBEBB37D
©TIM : 00:00:00:17
©TSC : 24000
©TSZ : 1001

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L5
Format settings, CABAC : No
Format settings, ReFrames : 2 frames
Format settings, GOP : M=2, N=24
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 4mn 12s
Bit rate : 43.6 Mbps
Width : 1 280 pixels
Clean aperture width : 1 248 pixels
Height : 720 pixels
Clean aperture height : 702 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 1.972
Stream size : 1.28 GiB (99%)
Language : English
Encoded date : UTC 2015-09-03 01:27:31
Tagged date : UTC 2015-09-03 01:27:47
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 4mn 12s
Source duration : 4mn 12s
Bit rate mode : Constant
Bit rate : 320 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 KHz
Compression mode : Lossy
Stream size : 9.39 MiB (1%)
Source stream size : 9.39 MiB (1%)
Language : English
Encoded date : UTC 2015-09-03 01:27:31
Tagged date : UTC 2015-09-03 01:27:47

Other
ID : 3
Type : Time code
Format : QuickTime TC
Duration : 4mn 12s
Time code of first frame : 00:00:00:17
Time code, striped : Yes
Language : English
Encoded date : UTC 2015-09-03 01:27:47
Tagged date : UTC 2015-09-03 01:27:47

Some of the compression settings listed by Youtube here are not available parameters in Compressor or MPEG Streamclip as far as I can tell:
https://support.google.com/youtube/answer/1722171?hl=en

I'm curious if I need to use another software like Sorenson's Sqeeze?
Can anyone recommend a solution? My client would like to publish on Youtube rather than Vimeo as this is a music video and will benefit from being on their search engine.

Thanks in advance for any help!


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Craig Seeman
Re: Youtube Processing creating artifacts in shadows and midtones... only
on Sep 3, 2015 at 1:08:46 pm

Compressor 4.2 certainly allows you to enable CABAC. YouTube spec says GOP should be one half the frame rate so your N should = 12, not 24. Set Keyframe rate to 12. You should also set Profile to High. Multipass encoding can help if you only did single pass.

Compressing a compressed file will always result in additional loss. It may be most apparent in harder to compressor areas such as gradients and areas that may have more noise as well as areas with high contrast.



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