Add support for qualityRanking attribute in DASH manifests

[Janet101]

Description

This PR adds support for parsing the qualityRanking attribute from DASH MPD manifests and mapping it to the HLS SCORE attribute for video.js compatibility.

The qualityRanking attribute specifies the quality ranking of a representation relative to others in the same adaptation set. Higher values represent lower quality content. This is mapped to HLS's SCORE attribute, which serves the same purpose and allows video players to make more informed decisions about quality selection beyond just bandwidth considerations.

Example

<Representation id="high" bandwidth="2000000" qualityranking="10">
  ...
</Representation>

Output (HLS playlist attributes):

{
  NAME: 'high',
  BANDWIDTH: 2000000,
  SCORE: 1/(10 + 1),
  ...
}

Test Results

All tests pass successfully:

• ✅ 196 tests passing (0 failures)
• ✅ 100% coverage on parseAttributes.js
• ✅ Overall coverage: 96.64% statements, 89.46% branches

[Janet101]

Hi @gesinger @brandonocasey @gkatsev @forbesjo , hope you’re doing well 😄! This is my first contribution to the repo, would you mind taking a look when you have some time?
I’d really appreciate your feedback!

[gkatsev]

can internal usage of it be camelCased: qualityRanking

[Janet101]

can internal usage of it be camelCased: qualityRanking

Good suggestion, updated! 326627b

[Janet101]

Hi @gkatsev, @Essk ! Is there a process to follow before merging the PR? I don't have merge access yet , could you help out? Thanks so much!

[Essk]

Thanks @Janet101 — and sorry for the delay. The red unit/coverage checks here are a fork-PR artifact: PRs from forks don't get access to the repo's BrowserStack secrets, so the browser test step can't authenticate and fails early. It's not a problem with your change.

I ran the full suite locally on this branch to confirm:

• lint — 0 errors
• test:node (qunit) — 196 pass / 0 fail
• test:browser (Chrome Headless) — 196 SUCCESS

All green. Merging — CI will run with secrets on main and should go green there.