LGTM3, to remove in 108 without deprecation period. On Wed, Sep 21, 2022 at 5:25 PM Mike Taylor <miketa...@chromium.org> wrote:
> LGTM2 > > On 9/21/22 7:44 AM, Yoav Weiss wrote: > > LGTM1 > > It seems unlikely that even the (few) developers who access this data are > somehow relying on it. > > On Tue, Sep 20, 2022 at 8:10 PM Dale Curtis <dalecur...@chromium.org> > wrote: > >> On Tue, Sep 20, 2022 at 3:36 AM Yoav Weiss <yoavwe...@chromium.org> >> wrote: >> >>> >>> >>> On Fri, Sep 16, 2022 at 11:19 PM Dale Curtis <dalecur...@chromium.org> >>> wrote: >>> >>>> Contact emails dalecur...@chromium.org >>>> >>>> Explainer None >>>> >>>> Specification https://github.com/w3c/webcodecs/issues/508 >>>> >>>> Summary >>>> premultiplyAlpha tells ImageDecoder to multiply the alpha channel into >>>> the RGB channels of decoded images. It was added to mirror the capabilities >>>> of ImageBitmapOptions, but in retrospect doesn't make sense. >>>> >>>> Feature has no observable effects in primary use cases (drawing), but >>>> may constrain implementations in suboptimal ways. E.g., requiring YUV be >>>> converted to RGB. See https://github.com/w3c/webcodecs/issues/508 for >>>> a more detailed description. Per consensus of WebCodecs spec editors and >>>> lack of usage (0.000000339% - 0.00000687% of page loads per a UseCounter in >>>> M105), we propose deprecating and removing this feature starting with M108. >>>> >>> >>> What would breakage look like? What would happen to callers who still >>> pass that option? >>> >> >> If they're just drawing the frames into canvas, webgl, etc there is no >> observable difference or breakage (this is the common use case) - since the >> draw stage takes care of any alpha blending. If they're accessing the raw >> pixels via VideoFrame::copyTo() they would notice that the alpha is no >> longer premultiplied. Depending on what the application is doing with the >> frames this may mean nothing (i.e., not using images w/ alpha, or didn't >> care about alpha) or it could result in color changes in the image. >> >> >>> >>> >>>> >>>> Blink component Blink>Media>WebCodecs >>>> <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EMedia%3EWebCodecs> >>>> >>>> TAG review Not applicable >>>> TAG review status Not applicable >>>> >>>> Risks >>>> It's possible that there exists some client which was accessing raw >>>> pixel data in JavaScript may observe that the alpha channel is no longer >>>> premultiplied into RGB channels. Clients wishing for this functionality can >>>> either do the multiply themselves or use createImageBitmap() to do this. >>>> >>>> Interoperability and Compatibility >>>> >>>> >>>> *Gecko*: Positive Firefox co-editor supports removal. >>>> >>> >>> I don't know if we can consider this >>> <https://github.com/w3c/webcodecs/issues/508#issuecomment-1248720618> a >>> Mozilla position. At the same time, this seems small enough to not warrant >>> an explicit issue. (and it's good to have consensus on the issue) >>> >> >> That's a bit surprising. I think that's a pretty strong signal, but defer >> to the API owners. >> > > That's a strong signal from the person editing the spec, but not an > official Mozilla position. > > >> >> >>> >>> >>>> >>>> *WebKit*: No signal >>>> >>>> *Web developers*: No signals >>>> >>>> *Other signals*: Microsoft co-editor supports removal. >>>> >>>> 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? >>>> >>>> >>>> No. >>>> >>>> >>>> Debuggability >>>> >>>> n/a >>>> >>>> >>>> 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 >>>> >>>> Flag name n/a >>>> >>>> Requires code in //chrome? False >>>> >>>> Tracking bug >>>> https://bugs.chromium.org/p/chromium/issues/detail?id=1340190 >>>> >>>> Launch bug >>>> https://bugs.chromium.org/p/chromium/issues/detail?id=1340190 >>>> >>>> Estimated milestones >>>> >>>> M108 >>>> >>>> >>>> Anticipated spec changes >>>> >>>> Open questions about a feature may be a source of future web compat or >>>> interop issues. Please list open issues (e.g. links to known github issues >>>> in the project for the feature specification) whose resolution may >>>> introduce web compat/interop risk (e.g., changing to naming or structure of >>>> the API in a non-backward-compatible way). >>>> https://github.com/w3c/webcodecs/pull/562 >>>> >>>> Link to entry on the Chrome Platform Status >>>> https://chromestatus.com/feature/4560781148946432 >>>> >>>> This intent message was generated by Chrome Platform Status >>>> <https://chromestatus.com/>. >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "blink-dev" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to blink-dev+unsubscr...@chromium.org. >>>> To view this discussion on the web visit >>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAPUDrwc%3D7%2B2KC73kKTUdWUmvQNubFtZGphhh8DXgQXnr%2BJc_LQ%40mail.gmail.com >>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAPUDrwc%3D7%2B2KC73kKTUdWUmvQNubFtZGphhh8DXgQXnr%2BJc_LQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to blink-dev+unsubscr...@chromium.org. > To view this discussion on the web visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAL5BFfVQSA6gRu8eVfRyu8TPwXQhqduSVDZemsX0%3DGV4nY2jfg%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAL5BFfVQSA6gRu8eVfRyu8TPwXQhqduSVDZemsX0%3DGV4nY2jfg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to blink-dev+unsubscr...@chromium.org. > To view this discussion on the web visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/096e70e9-197e-4859-3196-6f3277e94f7a%40chromium.org > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/096e70e9-197e-4859-3196-6f3277e94f7a%40chromium.org?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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