Bug 174456 – WebRTC: silence data not sent for disabled audio track

• Status: RESOLVED
• Resolution: FIXED
• Component: New Bugs

[Andrew Morris]

jsbin: https://output.jsbin.com/doweto

Press start, call

Output:
{
  "pollIndex": 71,
  "audioBytesSent": 0,
  "videoBytesSent": 7412286
}

Expected output:
{
  "pollIndex": 71,
  "audioBytesSent": <not zero>, // <--- difference here
  "videoBytesSent": 7412286
}

---

If you disable video instead, a little video data is still sent for the black frames. In a similar way, when audio is disabled, a little silence data should be sent too. At tokbox, we use these data to ensure the stream is working properly at the SFU and will reject the stream if video/audio is disabled during startup (if it is set from the very start it will accept it). The spec says this silence data should be sent:

"If track is ended, or if track.muted is set to true, the RTCRtpSender sends silence (audio) or a black frame (video). If track is set to null then the RTCRtpSender does not send."

Chrome and FF have this behaviour using the jsbin provided.

[Radar WebKit Bug Importer]

<rdar://problem/33284623>

[youenn fablet]

Created attachment 315350 [details]
Patch

[Eric Carlson]

Comment on attachment 315350 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=315350&action=review

> Source/WebCore/platform/mediastream/mac/RealtimeOutgoingAudioSource.cpp:95
> +    bool isMuted = m_muted || !m_enabled;

Minor nit: "isMuted" is slightly misleading, maybe "isSilenced" or "sendSilence"?

[Build Bot]

Comment on attachment 315350 [details]
Patch

Attachment 315350 [details] did not pass mac-debug-ews (mac):
Output: http://webkit-queues.webkit.org/results/4113907

New failing tests:
storage/indexeddb/modern/new-database-after-user-delete.html

[Build Bot]

Created attachment 315355 [details]
Archive of layout-test-results from ews116 for mac-elcapitan

The attached test failures were seen while running run-webkit-tests on the mac-debug-ews.
Bot: ews116  Port: mac-elcapitan  Platform: Mac OS X 10.11.6

[Build Bot]

Comment on attachment 315350 [details]
Patch

Attachment 315350 [details] did not pass ios-sim-ews (ios-simulator-wk2):
Output: http://webkit-queues.webkit.org/results/4113915

New failing tests:
imported/w3c/IndexedDB-private-browsing/idbfactory_open12.html

[Build Bot]

Created attachment 315357 [details]
Archive of layout-test-results from ews125 for ios-simulator-wk2

The attached test failures were seen while running run-webkit-tests on the ios-sim-ews.
Bot: ews125  Port: ios-simulator-wk2  Platform: Mac OS X 10.12.5

[youenn fablet]

Both tests are indexed db tests and are not impacted by this change.

[youenn fablet]

Created attachment 315465 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 315465 [details]
Patch

Clearing flags on attachment: 315465

Committed r219524: <http://trac.webkit.org/changeset/219524>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Aiham Hammami]

Is this fix included in Safari Tech Preview Release 38?

I'm still seeing this behaviour in Safari Tech Preview Release 38 (Safari 11.1, WebKit 12605.1.3.1).

1. Navigate to https://output.jsbin.com/doweto
2. Ensure Audio is unchecked, and Video is checked
3. Press Start, then Call

Actual Output:
{
  "pollIndex": 117,
  "audioBytesSent": 0,
  "videoBytesSent": 12122541
}


Expected Output:
{
  "pollIndex": 117,
  "audioBytesSent": <not zero>,
  "videoBytesSent": 12122541
}

This works as expected when Audio is checked and Video is unchecked.