====== Encoding-Quality-Testing ======
Created with the [[https://github.com/voc/voctoquality|voctoquality]] repo.

===== Reference content =====
Reference content is either our own (https://media.ccc.de) or from Xiph (https://media.xiph.org/video/derf/).

The specific sources are found in https://github.com/voc/voctoquality/blob/master/data/sources.json

All the reference content is converted to 8bit 1080p25.

===== Software =====
  * ffmpeg-4.1.4 (same as in buster)
  * libvmaf-1.3.15
  * libvpx-1.8.2 (bullseye)
  * libx264-2:0.155.2917+git0a84d98-2 (bullseye)

===== Testing VAAPI vs. software encoding for live streaming =====
The codec settings are the ones currently in use by the C3VOC for live streaming.

See https://github.com/voc/voctoquality/blob/master/data/profiles/voc_streaming.py for the specific ffmpeg options.

The codecs are tested with bitrates from 1Mbit/s to 5.2Mbit/s.

==== Graphs ====
{{ :experiment:streaming_rates.pdf |}}
{{ :experiment:streaming_refs.pdf |}}
{{ :experiment:streaming_speeds.pdf |}}

==== Comments ====

^ Platform                                         ^ Label        ^ Hardware Codecs    ^ Comments                                                                                                                                                        ^
^ Intel 6th Gen (i7-6600U)                         | skylake      | h.264, h.265       | h.264 scores better than our VP9 and x264 streaming settings and is pretty fast\\ h.265 even scores a little bit higher but is considerably slower              |
^ Intel 8th Gen (i7-8665U)                         | whiskeylake  | h.264, h.265, VP9  | h.264 and h.265 results worse but faster than skylake, have to check whats up with that\\ VP9 scores worse than H.264 and has broken rate-control for <2mbit/s  |
^ AMD Navi (RX 5700 XT) + Ryzen 2nd Gen (R5-2600)  | navi10       | h.264, h.265       | h.264 is worse than x264 on veryfast...\\ h.265 produces 1920x1088 output?                                                                                      |
^ Nvidia Turing (RTX2080 Super)                    | turing       | h.264, h.265       | nvidia-driver-460, cuda-toolkit 9.1.85\\ best h.265 encode, h.264 behind Intel                                                                                  |


==== Finding a Tracker VP9 Profile ====
=== HD-Profile ===

Goals: 
  * improve quality over previous libvpx (VP8) profile
  * don't increase encoding time too much
  * smaller size but similar quality as x264 master


Notes:
  * realtime + speed <= 3: slower and worse than quality good

```
-i $ref
-c:v libvpx-vp9
-quality:v good
-crf:v 30
-b:v 6000k
-maxrate:v 8000k
-minrate:v 2000k
-row-mt 1
-frame-parallel:v 1 -tile-columns:v 2
```

=== SD-Profile ===
  * worse parallelization and therefore speed than HD-profile
  * worse rate-control than HD-profile (doesn't reach target bitrate)
  * bufsize doesn't change anything
  * no threads parallelizes best
  * frame-parallel doesn't work (frame too small?)
  * bitrate with crf is more like maxrate