Fix perf regression in screenshare temporal layer bitrate allocation

A recent cl (https://codereview.webrtc.org/2510583002) introduced an
issue where temporal layers may return incorrect bitrates, given that
they are stateful and that the GetPreferredBitrateBps is called.
The fix is to use a temporary simulcast rate allocator instance, without
temporal layers, and get the preferred bitrate from that.

Additionally, some regression in bitrate allocated stems from overly
often reconfiguring the encoder, which yields suboptimal rate control.
The fix here is to limit encoder updates to when values have actually
changed.

As a bonus, dchecks added by this cl found a bug in the (unused) RealtimeTemporalLayers implementation. Fixed that as well.

BUG=webrtc:6301, chromium:666654

Review-Url: https://codereview.webrtc.org/2529073003
Cr-Commit-Position: refs/heads/master@{#15250}
6 files changed
tree: d06999e19f51010af05c9b61a893638851820909
  1. build_overrides/
  2. chromium/
  3. data/
  4. infra/
  5. resources/
  6. third_party/
  7. tools/
  8. webrtc/
  9. .clang-format
  10. .git-blame-ignore-revs
  11. .gitignore
  12. .gn
  13. AUTHORS
  14. BUILD.gn
  15. check_root_dir.py
  16. codereview.settings
  17. DEPS
  18. LICENSE
  19. license_template.txt
  20. LICENSE_THIRD_PARTY
  21. OWNERS
  22. PATENTS
  23. PRESUBMIT.py
  24. pylintrc
  25. README.md
  26. setup_links.py
  27. sync_chromium.py
  28. WATCHLISTS
README.md

WebRTC is a free, open software project that provides browsers and mobile applications with Real-Time Communications (RTC) capabilities via simple APIs. The WebRTC components have been optimized to best serve this purpose.

Our mission: To enable rich, high-quality RTC applications to be developed for the browser, mobile platforms, and IoT devices, and allow them all to communicate via a common set of protocols.

The WebRTC initiative is a project supported by Google, Mozilla and Opera, amongst others. This page is maintained by the Google Chrome team.

Development

See http://www.webrtc.org/native-code/development for instructions on how to get started developing with the native code.

More info