Answers.Body: <p>The VMAF models are actually trained by humans who rated the quality on a 1-5 point scale, watching the movie either on an 1080p screen from 3x screen height away, or on a 4k screen from 1.5x screen height away. This rating is mapped to VMAF scores 0, 20, 40, 60, and 80, while 100 is when they compare the source video to itself. Your score of 94.240835 is somewhere between what humans rated the highest and lossless.</p>
  <p>The VIF scores refer to <a href="https://en.wikipedia.org/wiki/Visual_Information_Fidelity" rel="nofollow noreferrer">Visual Information Fidelity</a> but I don't know what the scale numbers mean there. Don't know about adm2 or motion2 scores.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-09-28T02:01:50.420Z
Answers.LastActivityDate: 2020-09-28T02:01:50.420Z
Answers.UserDisplayName: stribika
Answers.Body: <p>The numbers don’t mean anything. They only have value when compared to other values. You can compare the results between two encodes of the same file and determine which encode produced better results.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-05T20:54:37.153Z
Answers.Text: How do I decide what a good threshold is? Like, If I make encodes with varying bitrates, I know more is better, but how much is enough?
Answers.UserDisplayName: chew socks
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-05T21:57:07.517Z
Answers.Text: That’s subjective. You get to decide what is “good enough” for your case.
Answers.UserDisplayName: SlimSCSI
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-06T03:31:20.000Z
Answers.Text: If you wanted to encode something so that your average non-expert wouldn't be able to tell the difference from the original, what numbers would you target? ;)
Answers.UserDisplayName: chew socks
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-06T19:12:05.870Z
Answers.Text: Like @SlimSCSI said, the scores are relative to the source material. There is no specific number to shoot for. If you are tweaking the encoder on a case by case basis, you can compare different settings by score. If you are setting up a "factory" workflow, run several test files through to find the better settings. If you are doing a QC workflow, you will have to experiment with your threshold for your specific set up.
Answers.UserDisplayName: Michael Liebman
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-12T23:07:22.437Z
Answers.Text: I found on the [mux.com blog](https://mux.com/blog/better-video-quality-through-deep-learning/) that a difference of 6 is barely noticeable. "A 6-point difference is VMAF is considered a Just-Noticeable-Difference."
Answers.UserDisplayName: chew socks
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-05T15:04:14.037Z
Answers.LastActivityDate: 2018-06-05T15:04:14.037Z
Answers.UserDisplayName: SlimSCSI
Answers.Body: <p>In general, the higher the <a href="https://medium.com/netflix-techblog/toward-a-practical-perceptual-video-quality-metric-653f208b9652" rel="nofollow noreferrer">VMAF score</a>, the higher the quality of the video will be perceived by the viewer. Lower VIF component and ADM scores indicate problems caused by intra-frame compression artifacts. A lower motion score indicates problems caused by inter-frame compression artifacts.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-05T20:49:49.310Z
Answers.Text: What scale is `VMAF_feature_motion2_score` on? I can tell the others are from 0-1, but not what the maximum of `VMAF_feature_motion2_score` is.
Answers.UserDisplayName: chew socks
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-06T19:16:51.653Z
Answers.Text: I don't know what the scale is. It doesn't seem to be described in the blog post, but you should be able to determine it from [the source code](https://github.com/Netflix/vmaf).
Answers.UserDisplayName: Michael Liebman
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-12T23:05:14.897Z
Answers.Text: I found it in the README, it varies from 0 to 20.
Answers.UserDisplayName: chew socks
Answers.ContentLicense: CC BY-SA 4.0
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Answers.LastActivityDate: 2018-06-05T15:16:57.973Z
Answers.UserDisplayName: Michael Liebman
Body: <p>I've been encoding some clips and then analyzing them with the VMAF tool from Netflix, but I don't know how to understand the results.</p>
  
  <p>This is the overall <code>mean</code> section of one of my tests.</p>
  
  <pre><code>VMAF_feature_adm2_score:0.982934
  VMAF_feature_motion2_score:2.262897
  VMAF_feature_vif_scale0_score:0.727423
  VMAF_feature_vif_scale1_score:0.946992
  VMAF_feature_vif_scale2_score:0.975502
  VMAF_feature_vif_scale3_score:0.986295
  VMAF_score:94.240835
  </code></pre>
  
Tags: <encoding><video-quality><transcoding>
Title: How should I interpret the results from Netflix VMAF
UserDisplayName: chew socks
ThreadText: # How should I interpret the results from Netflix VMAF
  
  (Asked by: username_0 on 2018-06-05)
  
  I've been encoding some clips and then analyzing them with the VMAF tool from Netflix, but I don't know how to understand the results.
  
  This is the overall `mean` section of one of my tests.
  
  ```
  VMAF_feature_adm2_score:0.982934
  VMAF_feature_motion2_score:2.262897
  VMAF_feature_vif_scale0_score:0.727423
  VMAF_feature_vif_scale1_score:0.946992
  VMAF_feature_vif_scale2_score:0.975502
  VMAF_feature_vif_scale3_score:0.986295
  VMAF_score:94.240835
  
  ```
  
  **Tags:** encoding, video-quality, transcoding
  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_1 on 2020-09-28. Score: 3
  
  The VMAF models are actually trained by humans who rated the quality on a 1-5 point scale, watching the movie either on an 1080p screen from 3x screen height away, or on a 4k screen from 1.5x screen height away. This rating is mapped to VMAF scores 0, 20, 40, 60, and 80, while 100 is when they compare the source video to itself. Your score of 94.240835 is somewhere between what humans rated the highest and lossless.
  
  The VIF scores refer to [Visual Information Fidelity](https://en.wikipedia.org/wiki/Visual_Information_Fidelity) but I don't know what the scale numbers mean there. Don't know about adm2 or motion2 scores.
  
  
  ---
  
  ### Answer by username_2 on 2018-06-05. Score: 3
  
  The numbers don’t mean anything. They only have value when compared to other values. You can compare the results between two encodes of the same file and determine which encode produced better results.
  
  > **Comments:**
  > **username_0**: How do I decide what a good threshold is? Like, If I make encodes with varying bitrates, I know more is better, but how much is enough?  
  > **username_2**: That’s subjective. You get to decide what is “good enough” for your case.  
  > **username_0**: If you wanted to encode something so that your average non-expert wouldn't be able to tell the difference from the original, what numbers would you target? ;)  
  > **username_3**: Like @username_2 said, the scores are relative to the source material. There is no specific number to shoot for. If you are tweaking the encoder on a case by case basis, you can compare different settings by score. If you are setting up a "factory" workflow, run several test files through to find the better settings. If you are doing a QC workflow, you will have to experiment with your threshold for your specific set up.  
  > **username_0**: I found on the [mux.com blog](https://mux.com/blog/better-video-quality-through-deep-learning/) that a difference of 6 is barely noticeable. "A 6-point difference is VMAF is considered a Just-Noticeable-Difference."  
  
  ---
  
  ### Answer by username_3 on 2018-06-05. Score: 3
  
  In general, the higher the [VMAF score](https://medium.com/netflix-techblog/toward-a-practical-perceptual-video-quality-metric-653f208b9652), the higher the quality of the video will be perceived by the viewer. Lower VIF component and ADM scores indicate problems caused by intra-frame compression artifacts. A lower motion score indicates problems caused by inter-frame compression artifacts.
  
  > **Comments:**
  > **username_0**: What scale is `VMAF_feature_motion2_score` on? I can tell the others are from 0-1, but not what the maximum of `VMAF_feature_motion2_score` is.  
  > **username_3**: I don't know what the scale is. It doesn't seem to be described in the blog post, but you should be able to determine it from [the source code](https://github.com/Netflix/vmaf).  
  > **username_0**: I found it in the README, it varies from 0 to 20.  
  
  ---
  
  