LGTM3
On 10/19/26 2:12 p.m., 'Dan Clark' via blink-dev wrote:
LGTM2
On Monday, October 19, 2026 at 11:10:54 AM UTC-7 [email protected]
wrote:
LGTM1
On Thursday, October 15, 2026 at 4:46:50 PM UTC-7 Chromestatus wrote:
*Contact emails*
[email protected], [email protected]
*Explainer*
https://github.com/MicrosoftEdge/MSEdgeExplainers/blob/main/OfflineAudioContext/explainer.md
*Specification*
https://webaudio.github.io/web-audio-api/#dom-offlineaudiocontext-startrendering
*Summary*
This feature adds an incremental rendering mechanism to
OfflineAudioContext so that the audio graph data can be
incrementally processed rather than allocating the whole audio
buffer up front. By incrementally delivering the data using
data chunks, there is no need to have high memory requirements
for the user's machine when processing high amounts of data.
*Blink component*
Blink>WebAudio
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EWebAudio%22>
*Web Feature ID*
Missing feature
*Motivation*
The OfflineAudioContext API works well for rendering small
audio graphs, but it does not scale for larger projects
because it allocates the full graph's AudioBuffer up front.
For example, rendering a 2-hour video composition project in
clipchamp.com <https://clipchamp.com> in an
OfflineAudioContext would require an extremely large
AudioBuffer allocation. The implication of this API is that a
user's computer must have enough available memory to export
the project even if the in-memory audio buffer will eventually
be discarded after it is written to a file. In situations with
limited hardware resources or low-powered devices, this
limitation makes WebAudio unusable as an offline processor. If
memory capacity is exceeded on a user's machine, then the
processing will stop and the browser may terminate the
tab/window leading to potential loss of data for the user and
a poor user experience.
*Initial public proposal*
https://github.com/WebAudio/web-audio-api/issues/2445
*TAG review*
https://github.com/w3ctag/design-reviews/issues/1282
*TAG review status*
Pending
*Goals for experimentation*
None
*Risks*
*Interoperability and Compatibility*
Low risk. - This feature is additive, meaning that the current
functionality/API is preserved. - Mozilla has actively
participated in the spec discussion/writing and approved the
already merged spec proposal. - Feature detection can be done
by checking the existence of OfflineAudioContext.close()
/Gecko/: No
signal (https://github.com/mozilla/standards-positions/issues/1456)
Although
not officially "positive" in their GitHub repo, Mozilla
position should be positive. They were very active in the WG
and also reviewed and approved the spec changes.
/WebKit/: No
signal (https://github.com/WebKit/standards-positions/issues/724)
/Web developers/:
Positive (https://github.com/WebAudio/web-audio-api/issues/2445)
Developers
from ClipChamp and Mediabunny participated in the spec
discussions and support the feature.
/Other signals/:
*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 risk. This is an additive feature to the
OfflineAudioContext API.
*Debuggability*
/No information provided/
*Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, ChromeOS, 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
WPTs are being implemented in
https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/web_tests/external/wpt/webaudio/the-audio-api/the-offlineaudiocontext-interface/:
https://wpt.fyi/results/webaudio/the-audio-api/the-offlineaudiocontext-interface/offlineaudiocontext-incremental-rendering.html?label=experimental&label=master&aligned
<https://wpt.fyi/results/webaudio/the-audio-api/the-offlineaudiocontext-interface/offlineaudiocontext-incremental-rendering.html?label=experimental&label=master&aligned>
https://wpt.fyi/results/webaudio/the-audio-api/the-offlineaudiocontext-interface/offlineaudiocontext-incremental-rendering-data-integrity.html?label=experimental&label=master&aligned
<https://wpt.fyi/results/webaudio/the-audio-api/the-offlineaudiocontext-interface/offlineaudiocontext-incremental-rendering-data-integrity.html?label=experimental&label=master&aligned>
https://wpt.fyi/results/webaudio/the-audio-api/the-offlineaudiocontext-interface/offlineaudiocontext-close.html?label=experimental&label=master&aligned
<https://wpt.fyi/results/webaudio/the-audio-api/the-offlineaudiocontext-interface/offlineaudiocontext-close.html?label=experimental&label=master&aligned>
*Flag name on about://flags*
N/A
*Finch feature name*
OfflineAudioContextIncrementalRendering
*Rollout plan*
Will ship enabled for all users
*Requires code in //chrome?*
False
*Tracking bug*
https://issues.chromium.org/issues/530596178
*Measurement*
We are going to use the following UseCounters to measure
adoption: OfflineAudioContextStartRendering and
OfflineAudioContextClose
*Availability expectation*
Feature is available only in Chromium browsers for the
foreseeable future.
*Adoption expectation*
Feature is used by specific partner(s) to provide
functionality within 12 months of launch in Chrome.
*Adoption plan*
We are in contact with partners via internal channels and the
W3C 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?
None.
*Estimated milestones*
Shipping on desktop 158
Shipping on Android 158
Shipping on WebView 158
*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/pull/2675
*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/5109900936085504?gate=6495103520735232
*Links to previous Intent discussions*
Intent to Prototype:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6a908411.8ed5e303.29aee.0236.GAE%40google.com
This intent message was generated by Chrome Platform Status
<https://chromestatus.com>.
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