LGTM to experiment from M145 to M150 inclusive.
On 1/21/26 4:04 p.m., Michael Wilson wrote:
*Contact emails*
[email protected], [email protected]
*Specification*
https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-renderquantumsize
*Summary*
AudioContext and OfflineAudioContext now take an optional
renderSizeHint, which allows users to ask for a particular render
quantum size when an integer is passed, to use the default of 128
frames if nothing or "default" is passed, or to ask the User-Agent to
pick a good render quantum size if "hardware" is specified.
*Blink component*
Blink>WebAudio
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EWebAudio%22>
*Web Feature ID*
web-audio <https://webstatus.dev/features/web-audio>
*TAG review*
https://github.com/w3ctag/design-reviews/issues/895
*TAG review status*
Issues addressed
*Origin Trial documentation link*
https://webaudio.github.io/web-audio-api/#dom-audiocontextoptions-rendersizehint
*Risks*
*Interoperability and Compatibility*
Low. The feature is already specified.
/Gecko/: No
signal (https://github.com/WebAudio/web-audio-api/pull/2469) A Firefox
developer wrote the specification change.
/WebKit/: No signal
/Web developers/:
Positive (https://github.com/WebAudio/web-audio-api/issues/1503) Developers
have requested a way to increase the render quantum size, and are
looking forward to the feature being implemented.
/Other signals/:
*Ergonomics*
An identified use case of this feature is to match buffer sizes used
by other Chromium audio APIs, in order to improve performance.
*Activation*
There is an ongoing privacy discussion about how to mitigate
fingerprinting concerns around the "hardware" hint
(https://github.com/WebAudio/web-audio-api/issues/2659). The
"hardware" hint as implemented in Chromium currently will always
return the default 128 render quantum size, which exposes no user
information. This is allowed by the spec, which says "It is a hint
that might not be honored."
*Security*
There is concern that a very low render quantum size could allow an
AudioWorklet to create a high-resolution timer, but very high sample
rates are already allowed and have a similar risk so the marginal
change in security is probably low.
*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?
Low. The change is to ship a new API.
*Goals for experimentation*
Validate performance improvement gained by matching render quantum
size to software buffer sizes when using a numeric renderSizeHint.
Verify actual audio processing output is unchanged when using a
numeric renderSizeHint.
We have a primary partner for this Origin Trial, and we would like to
see if the performance and ergonomics of the API satisfy this
partner's need. This partner is not going to use the "hardware" hint,
and we think that it is still valuable to conduct an Origin Trial to
gather feedback on the rest of the API.
*Ongoing technical constraints*
None.
*Debuggability*
It may be worth exposing the render quantum size value in the DevTools
WebAudio pane, similar to sample rate.
*Will this feature be supported on all six Blink platforms (Windows,
Mac, Linux, ChromeOS, Android, and Android WebView)?*
Yes
All supported platforms have mechanisms to implement this feature.
*Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?*
Yes
https://wpt.fyi/results/webaudio/the-audio-api/the-audiocontext-interface/audiocontext-rendersizehint.html
https://wpt.fyi/results/webaudio/the-audio-api/the-offlineaudiocontext-interface/offlineaudiocontext-rendersizehint.html
*Flag name on about://flags*
N/A (launch with --enable-features=WebAudioConfigurableRenderQuantum)
*Finch feature name*
WebAudioConfigurableRenderQuantum
*Requires code in //chrome?*
False
*Tracking bug*
https://crbug.com/40637820
*Launch bug*
https://launch.corp.google.com/launch/4416924
*Measurement*
UseCounters: WebAudioRenderSizeHint, WebAudioRenderQuantumSize
*Availability expectation*
We expect that Firefox will implement the feature independently at
some point.
*Adoption expectation*
We expect that specific partners will use this functionality
immediately upon its launch in Chrome.
*Adoption plan*
We are communication with partners, and also in communication with
Mozilla via the Audio Working Group.
*Non-OSS dependencies*
Does the feature depend on any code or APIs outside the Chromium open
source repository and its open-source dependencies to function?
No.
*Estimated milestones*
Shipping on desktop 150
Origin trial desktop first 145
Origin trial desktop last 150
DevTrial on desktop 145
Shipping on Android 150
Origin trial Android first 145
Origin trial Android last 150
Shipping on WebView 150
Origin trial WebView first 145
Origin trial WebView last 150
*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/WebAudio/web-audio-api/issues/2663
https://github.com/WebAudio/web-audio-api/issues/2664
*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/5078190552907776?gate=5140327991869440
*Links to previous Intent discussions*
Intent to Prototype:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/688d3254.2b0a0220.361edb.0299.GAE%40google.com
This intent message was generated by Chrome Platform Status
<https://chromestatus.com/>.
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