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zebra-spaces: surface getDisplayMedia audio-track count + browser-specific hint

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Firefox getDisplayMedia silently drops audio for window/tab sources (only
'entire screen' carries system audio). Users were broadcasting video-only
without knowing the audio never made it into the captured stream.

Log the captured track counts unconditionally; when audio is 0 explain
the limitation per browser and point to the workaround (route the tab
through mic music mode for high-quality stereo broadcast).
This commit is contained in:
Russell Ballestrini 2026-06-01 20:27:38 -04:00
parent 6fbeade12d
commit 1294e96f01
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1 changed files with 16 additions and 2 deletions
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18
web/zebra-spaces.html
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@ -733,6 +733,20 @@ async function sfuPublishScreen(){
});
} catch(e){ logLine('err','screen share cancelled: '+e.message); return; }
sfuScreenStream = stream;
const vTracks = stream.getVideoTracks(), aTracks = stream.getAudioTracks();
logLine('', 'screen capture: '+vTracks.length+' video + '+aTracks.length+' audio track(s)');
if (aTracks.length === 0){
/* Firefox getDisplayMedia never captures tab/window audio — only the
* 'entire screen' source carries system audio, and only on some
* platforms. Chrome captures tab audio when the user ticks 'share
* audio' in the picker. Make the limitation visible instead of
* silently broadcasting video-only. */
const ua = navigator.userAgent;
const ff = /Firefox/.test(ua);
logLine('err','no audio captured — '+(ff
? 'Firefox getDisplayMedia ignores tab/window audio. Share "entire screen" with system audio, or stream the audio via mic music mode (toggle music mode + route the tab through your mic).'
: 'tick the "share tab/system audio" checkbox in the picker, or use music-mode mic.'));
}
const pc = new RTCPeerConnection(rtcConfig);
for (const tr of stream.getTracks()){
if (tr.kind === 'video') tr.contentHint = 'detail'; /* favour pixel fidelity over framerate */
@ -1693,8 +1707,8 @@ logLine('', 'ready — pick a handle, type a rendezvous code, enter the space');
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