On Fri, Oct 4, 2019 at 6:54 AM Tom Ritter <t...@mozilla.com> wrote: > It's a bit hard for me to tell from the description - are these values > dependent on a user's hardware, performance of the user's computer, or > a user-chosen setting? If so we would want to support > resistFingerprinting. >
The spec allows the UA to base them on anything it sees fit, if the application leaves it to the UA to decide. Our implementation uses fixed and application-provided values, per below. There are three different modes of configuring these values for an application, and here's how we set them: 1) Application did no configuration at all: we use hardcoded values: 2.5Mbps for video and 128kbps for audio 2) Application configured audio and video respectively: we use the provided values 3) Application configured a total bitrate: Our implementation has a fixed algorithm for this -- its only inputs is the number of tracks and kinds of tracks, and the total bitrate configured is distributed according to a weighting where a video track gets 20 times as high a bitrate as audio, and they're capped within fixed limits. (see https://phabricator.services.mozilla.com/D41585#C1663069NL43 for the limits, and https://phabricator.services.mozilla.com/D41585#C1663069NL212 for the algorithm) Given this, I don't see the need for explicit resistFingerprinting support. -tom > > On Thu, Oct 3, 2019 at 9:54 PM Andreas Pehrson <pehrs...@mozilla.com> > wrote: > > > > As of Oct 4th I intend to land and ship the audioBitsPerSecond and > > videoBitsPerSecond attributes of MediaRecorder on all platforms. We've > > shipped MediaRecorder since Firefox 29. > > > > *Summary*: The audioBitsPerSecond and videoBitsPerSecond attributes of > > MediaRecorder reflect what an application has configured the > MediaRecorder > > to use (and which we already ship support for doing). In case it was > > configured with a total (audio+video) bitrate, or if it was not > configured > > at all, these attributes reflect what the UA has chosen to configure the > > MediaRecorder with. > > > > After starting a recording, these are again updated to reflect the > current > > configuration of the MediaRecorder, since tracks are now known and the UA > > may have recalculated the chosen bitrates based on the number and kind of > > tracks that are being recorded. > > > > At the same time I'm making our MediaRecorder implementation largely > > spec-compliant. There's work in bug 1514158 as well as bug 1512175, where > > the former is focusing on these attributes and the latter focuses on mime > > type handling. We landed spec clarifications for both of these recently. > > > > *Bug*: https://bugzilla.mozilla.org/show_bug.cgi?id=1514158 > > > > *Standard*: > > > https://w3c.github.io/mediacapture-record/MediaRecorder.html#dom-mediarecorder-videobitspersecond > > Clarifications were made to the spec to make this more interoperable. > These > > were approved by Google. > https://github.com/w3c/mediacapture-record/pull/175 > > > > *Platform coverage*: All > > > > *Preference*: There is no special pref for these attributes > > > > *DevTools bug*: There is no generic devtools support for MediaRecorder > > > > *Other browsers*: > > Chrome shipped (since 49, bug: > > https://bugs.chromium.org/p/chromium/issues/detail?id=262211), > > Safari shipped MediaRecorder but no attributes yet (behind an > experimental > > feature flag since TP73, bug: > https://bugs.webkit.org/show_bug.cgi?id=85851) > > > > *web-platform-tests*: I'm adding one as part of bug 1514158: > > https://phabricator.services.mozilla.com/D41584 > > > > *Secure contexts*: No, MediaRecorder is historically not restricted to > > secure contexts. However some APIs for getting access to the > > MediaStreamTracks needed to create a recorder are. > > > > > > Andreas Pehrson > > _______________________________________________ > > dev-platform mailing list > > dev-platform@lists.mozilla.org > > https://lists.mozilla.org/listinfo/dev-platform > _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
