Intent to Ship: New VP9 codec string and Profile 2 query support

[Husain Bengali]

Contact emails

hben...@chromium.org, chcunn...@chromium.org

 

Specs

Spec for new VP9 codec string:

http://www.webmproject.org/vp9/mp4/#codecs-parameter-string

 

TAG review is not applicable.

 

Link to “Intent to Implement” blink-dev discussion

https://groups.google.com/a/chromium.org/d/msg/blink-dev/a6rgcleYwzg/OmhPhfUGDQAJ

 

Summary

VP9 is an open and royalty-free video codec that has been supported in Chromium since 2013. This update adds a new string format for describing the encoding properties, such as the profile, level, etc. Such properties are common in video codecs but are not exposed in the current VP9 string format. In addition, this update includes using the new format to advertise support for VP9 Profile 2. The string format is accepted by media-related APIs, including MediaSource.isTypeSupported(), HTMLMediaElement.canPlayType(), and EME’s requestMediaKeySystemAccess().

 

For example, the codec string parameter for VP9 Profile 2 could be vp09.02.10.10.01.09.16.09.01. Details on how the codec string is constructed can be found in the VP9 media file format binding spec linked to above.

 

Is this feature supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?

Yes

 

Interoperability and Compatibility Risk

The change was discussed with Netflix, YouTube and Microsoft. Therefore, we expect the interoperability/compatibility risks to be very low, the discussion being mostly around formatting the string.

 

Edge: Positive

Firefox: No signals

Safari: No signals

Web developers: Positive

 

Is this feature fully tested by web-platform-tests?

 

Since media types aren't defined in specs, this section isn’t strictly applicable. We do, however, intend to write tests, and have filed issues to track this work:

 

https://bugs.chromium.org/p/chromium/issues/detail?id=726009

https://github.com/w3c/media-source/issues/180

 

Launch tracking bug

https://crbug.com/672240

 

Entry on the feature dashboard

https://www.chromestatus.com/feature/6230726177456128

[PhistucK]

Is there a compatibility risk at all? I mean, it sounds backward compatible, so what could be risky here?

Or does this refer to silly cases like websites that use that string/profile, expecting it to fail and it suddenly works (or returns "probably") and so never-before-run code branches would start to run?

☆PhistucK

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[Chris Cunningham]

No compatibility risk is expected. The existing "vp9" string is still supported and will continue to give the same answers it did before. Its unlikely that anyone is currently using the new "vp09..." in their production apps since its only recently specified. 

I think the "low" risk is mostly about interop. We have some signals of support, but we haven't heard from all browser vendors. 

[j.j.]

Am Donnerstag, 25. Mai 2017 20:11:52 UTC+2 schrieb Chris Cunningham:

[...]

I think the "low" risk is mostly about interop. We have some signals of support, but we haven't heard from all browser vendors. 

https://bugzilla.mozilla.org/show_bug.cgi?id=1368092 (Add support for new VP9 codec string)

[TAMURA, Kent]

LGTM1

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TAMURA Kent
Software Engineer, Google

[Jochen Eisinger]

lgtm2

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[Philip Jägenstedt]

LGTM3

If https://bugzilla.mozilla.org/show_bug.cgi?id=1175876 isn't exactly this, can you file a Firefox bug for Profile 2? It'd be quite surprising if they don't want it, and if we're shipping and Edge plans to, then that might put it rather high on their priority list.

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[Chris Cunningham]

Thanks All. Philip, FF is tracking implementation of the new string here: https://bugzilla.mozilla.org/show_bug.cgi?id=1368092

[Philip Jägenstedt]

Ah, thanks Chris.