On Wed, Jul 19, 2023 at 2:51 PM Philipp Hancke <
[email protected]> wrote:

> Am Mi., 19. Juli 2023 um 14:25 Uhr schrieb Yoav Weiss <
> [email protected]>:
>
>>
>>
>> On Thu, Jul 13, 2023 at 10:53 PM 'Eugene Zemtsov' via blink-dev <
>> [email protected]> wrote:
>>
>>> Any new feedback or resolution on this one?
>>>
>>> On Fri, Jul 7, 2023 at 5:53 AM Sangwhan Moon <[email protected]> wrote:
>>>
>>>> (resending from correct email)
>>>>
>>>> On 2023年07月07日 00時32分12秒 (+09:00), Mike Taylor wrote:
>>>>
>>>> On 7/5/23 8:57 PM, 'Eugene Zemtsov' via blink-dev wrote:
>>>>
>>>> Intent to Implement and Ship: Per-frame quantizer in VideoEncoder
>>>>
>>>> Contact emails
>>>>
>>>> [email protected]
>>>>
>>>> Explainer
>>>>
>>>> None
>>>>
>>>>
>> I think an explainer can be significantly helpful in helping us
>> understand how developers will be using this feature and what use cases
>> it'd cover.
>> Could you write one or add an inline explanation outlining that?
>>
>
> Explaining that is tough without going into the details "what is
> quantization for video codecs. See
>   https://www.vcodex.com/h264avc-4x4-transform-and-quantization/
> for a very detailed explanation for H264.
>
> the tl;dr is that folks who encode video like tuning all kinds of knobs to
> get the "best" result and qp is one of those.
>

An explainer doesn't have to assume folks reading it don't know what
quantization means :)

Basically, clicking through the specs, it's still not clear to me if the
quantization values are provided as a single int that quantization tables
are supposed to be divided by. a "quality" int that represents a certain
quantization table, or something else entirely. Clarity on that would be
great.


>
>>
>>>
>>>> Specification
>>>>
>>>> https://www.w3.org/TR/webcodecs/#video-encoder-bitrate-mode
>>>>
>>>> Summary
>>>>
>>>> Adds "quantizer" VideoEncoderBitrateMode for VideoEncoder. This allows
>>>> to specify a quantizer parameter for each frame for AV1, VP9, and AVC video
>>>> codecs. The quantizer parameter is set via codec specific extensions for
>>>> VideoEncoderEncodeOptions.
>>>>
>>>> Assuming I know very little about video codecs, what use cases does
>>>> this enable for developers?
>>>>
>>>>
>>>>
>>>> Blink component
>>>>
>>>> Blink>Media>WebCodecs
>>>> <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EMedia%3EWebCodecs>
>>>>
>>>> TAG review
>>>>
>>>> None.
>>>>
>>>> Previously WebCodecs API had TAG review as a whole:
>>>>
>>>> https://github.com/w3ctag/design-reviews/issues/612
>>>>
>>>> This is a new addition since that review, but it's a trivial addition
>>>> (IMHO) so a new review request isn't needed.
>>>>
>>>>
>>>> I agree, I don't see anything particularly contentious in the proposal
>>>> that would warrant a full review.
>>>>
>>>>
>>>>
>>>> TAG review status
>>>>
>>>> Not applicable
>>>>
>>>> Risks
>>>>
>>>> Interoperability and Compatibility
>>>>
>>>> Gecko: Neutral (
>>>> https://github.com/mozilla/standards-positions/issues/837#issuecomment-1614666364)
>>>> Paul Adenot (Mozilla) expressed that minor changes to WebCodecs spec don't
>>>> need to go through the full "Request for Mozilla Position" process assuming
>>>> they were approved by the Media Working Group.
>>>>
>>>> WebKit: Positive (
>>>> https://www.w3.org/2023/03/07-mediawg-minutes.html#t02) The issue was
>>>> discussed on 07 March 2023 by w3c Media working group. Jer Noble (Apple)
>>>> was actively participating and provided input for spec details.
>>>>
>>>> Can we request a formal position from WebKit, at least to let them know
>>>> we're intending to ship?
>>>>
>>>>
>>>> Web developers: Positive (https://github.com/w3c/webcodecs/issues/56)
>>>> People ask for this on GitHub
>>>>
>>>> Other signals:
>>>>
>>>> WebView application risks
>>>>
>>>> Does this intent deprecate or change behavior of existing APIs, such
>>>> that it has potentially high risk for Android WebView-based applications?
>>>>
>>>>
>>>>
>>>> Will this feature be supported on all six Blink platforms (Windows,
>>>> Mac, Linux, Chrome OS, Android, and Android WebView)?
>>>>
>>>> Yes
>>>>
>>>> Is this feature fully tested by web-platform-tests
>>>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>
>>>> ?
>>>>
>>>> Yes
>>>>
>>>> Tracking bug
>>>>
>>>> https://bugs.chromium.org/p/chromium/issues/detail?id=1424154
>>>>
>>>> Estimated milestones
>>>>
>>>> Shipping on desktop
>>>>
>>>> 117
>>>>
>>>> Shipping on Android
>>>>
>>>> 117
>>>>
>>>>
>>>>
>>>>
>>>> Link to entry on the Chrome Platform Status
>>>>
>>>> https://chromestatus.com/feature/5783986600673280
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Thanks,
>>>> Eugene Zemtsov.
>>>> --
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>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAK8JDrF0PKfpVbaYWX-hR0wJ%2Bb9H4YtwFBUc6Y6JGSmFT7pVgQ%40mail.gmail.com?utm_medium=email&utm_source=footer>
>>>> .
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>>>> .
>>>>
>>>>
>>>
>>> --
>>> Thanks,
>>> Eugene Zemtsov.
>>>
>>> --
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>>> .
>>>
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>>
>

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