On Tue, Feb 9, 2021 at 4:20 PM Chris Cunningham <chcunning...@chromium.org> wrote:
> +mmaxfi...@apple.com, who mentioned similar privacy concerns in a WebGPU > meeting back in October. > +jer.no...@apple.com, since we're recently talking about this spec in > Media WG meetings. > > Hi Group, > > Sorry to revive an old thread! I want to give a few updates. > > One request: please offer replies in the form of github issues. This helps > us track/scope the feedback. > https://github.com/WICG/web-codecs/issues > > > (let me know if there is a more detailed proposal). > > The specification is now quite detailed. > https://wicg.github.io/web-codecs/ > > > - Any media pipeline should be off the JS main thread, by default. > > This does not seem guaranteed by the proposal. > > The spec now mandates that the media pipeline work be offloaded to a > "codec thread". This may in fact be a fan out of many threads, but is not > allowed to be the main ("control") thread. > > > Capabilities is indeed an issue. The more you need to understand the > > codec, the wider is the API and the potential fingerprinting surface. > > The spec has an outstanding PR > <https://github.com/WICG/web-codecs/pull/120> to add a capabilities API > like so: > let supportInfo = await VideoDecoder.isConfigSupported({ codec: 'vp8', ... > }); > > We agree that this adds to the fingerprinting surface. I've added a Privacy > Considerations section > <https://wicg.github.io/web-codecs/#privacy-considerations> to describe > this in more detail and suggest possible mitigations. Happy to discuss this > more on the github. > > > WebCodec might also potentially expose precise timing information in > > how long it takes to decode/encode frames. Is it a way to identify > > which hardware is being used underneath? > > Possibly. Implementers might mitigate by adding artificial delay to emit > codec outputs. > > Best, > Chris > Apologies, I'm re-sending because my first attempt bounced for not having subscribed to this list.
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