Reviewed as part of WebRTC.
The getCapabilities() method returns the most optimistic view of the capabilities of the system for sending media of the given kind. It does not reserve any resources, ports, or other state but is meant to provide a way to discover the types of capabilities of the browser including which codecs or RTP extensions may be supported.
Users sometimes need to check the capabilities of the client. The sender capabilities can currently be retrieved by parsing the SDP generated when making an offer. This parsing is complex and error prone. There is currently no way to get the full capabilities of a receiver as they could differ from the sender's.
Without this feature, developers would also often hardcode the capabilities based on the user agent.
Firefox: No public signals
Edge: Shipped
Safari: No public signals
Web developers: Positive
Low risk. The feature is in the spec and is easy to detect. It has also been stable for a while and is not controversial.
Low risk. The API has not been implemented in other browsers except for Edge which implements the version from ORTC specification which is mostly compatible.
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to Chris Harrelson, Florent Castelli, blink-dev
LGTM2, parsing SDP and making assumption based on UA sniffing sound like decidedly not fun for web developers.
Glad to see there's a baseline of tests in WPT already, and presumably some additional test coverage will be added as part of the implementation as I've been so happy to see happen by routine with WebRTC recently :)
If I have one ask, it is to make sure that other browser vendors are well aware of this change, by finding or filing bugs tracking this. Pointing to this thread or https://crbug.com/857451 as well as tests they can use would be great.
On Mon, Jul 9, 2018 at 8:48 AM Florent Castelli <orp...@chromium.org> wrote:
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Florent Castelli
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Jul 10, 2018, 12:57:57 PM7/10/18
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to Joe Medley, blin...@chromium.org
Chris: Will do next time. Which template are you referring to? I used the one after filling the feature on Chrome Status.
Philip: Apart from Edge, the other browsers are still using an older version of the native WebRTC library that didn't have the matching feature. They should be able to implement it quickly when they upgrade to the latest version. I'll see what I can do regarding filling bugs.
Joe: It was an oversight on my part and the Chrome Status entry is now updated.
Joe Medley
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Jul 10, 2018, 5:52:27 PM7/10/18
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/* Opera Software, Linköping, Sweden: CEST (UTC+2) */
dull...@chromium.org
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Jul 16, 2018, 5:42:55 AM7/16/18
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to blink-dev
Hi Florent,
The spec mentions that this feature would increase the fingerprinting surface but I can't find any details about the data returned by these methods. Could you describe what the impact on fingerprinting will be?
Thanks,
Christian
Florent Castelli
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Jul 16, 2018, 8:23:52 AM7/16/18
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to dull...@chromium.org, blin...@chromium.org
The data returned is the list of supported codecs with a succint list of encoding parameters and RTP extensions.
This data will likely be the same for all browsers of the same version on a given platform.
Also as I said, that data can be retrieved from the SDP generated to initiate a negotiation and is required for the protocol to work.
A sample output for the sender audio capabilities on my machine can be seen below: