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Add captureTimestamp and senderCaptureTimeOffset to frame metadata
Fixes w3c#225
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‎index.bs

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Original file line numberDiff line numberDiff line change
@@ -48,6 +48,11 @@ spec:webidl; type:dfn; text:resolve
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"CloneArrayBuffer": {
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"href": "https://tc39.es/ecma262/#sec-clonearraybuffer",
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"title": "CloneArrayBuffer"
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},
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"RTP-EXT-CAPTURE-TIME": {
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"href": "https://webrtc.googlesource.com/src/+/refs/heads/main/docs/native-code/rtp-hdrext/abs-capture-time",
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"title": "RTP Header Extension for Absolute Capture Time",
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"publisher": "WebRTC Project"
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}
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}
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</pre>
@@ -293,6 +298,10 @@ The <dfn method for="SFrameTransform">setEncryptionKey(|key|, |keyID|)</dfn> met
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# RTCRtpScriptTransform # {#scriptTransform}
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In this section, the capture system refers to the system where media is sourced from and the sender system
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refers to the system that is sending RTP and RTCP packets to the receiver system where {{RTCEncodedVideoFrameMetadata}} data
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or {{RTCEncodedAudioFrameMetadata}} data is populated.
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## <dfn enum>RTCEncodedVideoFrameType</dfn> dictionary ## {#RTCEncodedVideoFrameType}
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<pre class="idl">
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// New enum for video frame types. Will eventually re-use the equivalent defined
@@ -358,6 +367,8 @@ dictionary RTCEncodedVideoFrameMetadata {
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sequence&lt;unsigned long&gt; contributingSources;
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long long timestamp; // microseconds
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unsigned long rtpTimestamp;
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DOMHighResTimeStamp captureTimestamp;
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DOMHighResTimeStamp senderCaptureTimeOffset;
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DOMString mimeType;
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};
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</pre>
@@ -430,6 +441,51 @@ dictionary RTCEncodedVideoFrameMetadata {
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The RTP timestamp identifier is an unsigned integer value per [[RFC3550]]
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that reflects the sampling instant of the first octet in the RTP data packet.
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</p>
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</dd>
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<dt>
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<dfn dict-member>captureTimestamp</dfn> <span class="idlMemberType">DOMHighResTimeStamp</span>
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</dt>
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<dd>
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<p>
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The {{captureTimestamp}} is the timestamp that, the most recent frame (from an RTP packet
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originating from this source) delivered to the {{RTCRtpReceiver}}'s {{MediaStreamTrack}}, was
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originally captured. Its reference clock is the capture system's NTP clock (same clock used
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to generate NTP timestamps for RTCP sender reports on that system).
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On populating this member, the user agent MUST run the following steps:
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1. If the relevant RTP packet contains the [[RTP-EXT-CAPTURE-TIME|RTP Header Extension for
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Absolute Capture Time]], return the value of the
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[[RTP-EXT-CAPTURE-TIME#absolute-capture-timestamp|absolute capture timestamp]] field and
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abort these steps.
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1. Otherwise, if the relevant RTP packet does not contain the RTP Header Extension for
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Absolute Capture Time but a previous RTP packet did, return the result of calculating the
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absolute capture timestamp according to [[RTP-EXT-CAPTURE-TIME#timestamp-interpolation|
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timestamp interpolation]] and abort these steps.
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1. Otherwise, return undefined.
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</p>
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</dd>
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<dt>
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<dfn dict-member>senderCaptureTimeOffset</dfn> <span class="idlMemberType">DOMHighResTimeStamp</span>
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</dt>
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<dd>
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<p>
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The {{senderCaptureTimeOffset}} is the sender system's estimate of the offset between its own
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NTP clock and the capture system's NTP clock, for the same frame that the {{captureTimestamp}} was
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originated from.
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On populating this member, the user agent MUST run the following steps:
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1. If the relevant RTP packet contains the [[RTP-EXT-CAPTURE-TIME|RTP Header Extension for Absolute
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Capture Time]] and the estimated [[RTP-EXT-CAPTURE-TIME#estimated-capture-clock-offset|capture
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clock offset field]] is present, return the value of the estimated capture clock offset field
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and abort these steps.
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1. Otherwise, if the relevant RTP packet does not contain the [[RTP-EXT-CAPTURE-TIME|RTP Header
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Extension for Absolute Capture Time]]'s [[RTP-EXT-CAPTURE-TIME#estimated-capture-clock-offset|
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estimated capture clock offset]] field, but a previous RTP packet did, return the most recent
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value that was present and abort these steps.
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1. Otherwise, return undefined.
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</p>
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</dd>
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<dt>
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<dfn dict-member>mimeType</dfn> <span class="idlMemberType">DOMString</span>
@@ -611,6 +667,8 @@ dictionary RTCEncodedAudioFrameMetadata {
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sequence&lt;unsigned long&gt; contributingSources;
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short sequenceNumber;
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unsigned long rtpTimestamp;
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DOMHighResTimeStamp captureTimestamp;
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DOMHighResTimeStamp senderCaptureTimeOffset;
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DOMString mimeType;
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};
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</pre>
@@ -664,6 +722,51 @@ dictionary RTCEncodedAudioFrameMetadata {
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that reflects the sampling instant of the first octet in the RTP data packet.
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</p>
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</dd>
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<dt>
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<dfn dict-member>captureTimestamp</dfn> <span class="idlMemberType">DOMHighResTimeStamp</span>
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</dt>
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<dd>
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<p>
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The {{captureTimestamp}} is the timestamp that, the most recent frame (from an RTP packet
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originating from this source) delivered to the {{RTCRtpReceiver}}'s {{MediaStreamTrack}}, was
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originally captured. Its reference clock is the capture system's NTP clock (same clock used
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to generate NTP timestamps for RTCP sender reports on that system).
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On populating this member, the user agent MUST run the following steps:
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1. If the relevant RTP packet contains the [[RTP-EXT-CAPTURE-TIME|RTP Header Extension for
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Absolute Capture Time]], return the value of the
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[[RTP-EXT-CAPTURE-TIME#absolute-capture-timestamp|absolute capture timestamp]] field and
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abort these steps.
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1. Otherwise, if the relevant RTP packet does not contain the RTP Header Extension for
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Absolute Capture Time but a previous RTP packet did, return the result of calculating the
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absolute capture timestamp according to [[RTP-EXT-CAPTURE-TIME#timestamp-interpolation|
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timestamp interpolation]] and abort these steps.
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1. Otherwise, return undefined.
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</p>
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</dd>
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<dt>
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<dfn dict-member>senderCaptureTimeOffset</dfn> <span class="idlMemberType">DOMHighResTimeStamp</span>
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</dt>
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<dd>
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<p>
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The {{senderCaptureTimeOffset}} is the sender system's estimate of the offset between its own
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NTP clock and the capture system's NTP clock, for the same frame that the {{captureTimestamp}} was
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originated from.
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On populating this member, the user agent MUST run the following steps:
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1. If the relevant RTP packet contains the [[RTP-EXT-CAPTURE-TIME|RTP Header Extension for Absolute
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Capture Time]] and the estimated [[RTP-EXT-CAPTURE-TIME#estimated-capture-clock-offset|capture
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clock offset field]] is present, return the value of the estimated capture clock offset field
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and abort these steps.
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1. Otherwise, if the relevant RTP packet does not contain the [[RTP-EXT-CAPTURE-TIME|RTP Header
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Extension for Absolute Capture Time]]'s [[RTP-EXT-CAPTURE-TIME#estimated-capture-clock-offset|
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estimated capture clock offset]] field, but a previous RTP packet did, return the most recent
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value that was present and abort these steps.
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1. Otherwise, return undefined.
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</p>
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</dd>
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<dt>
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<dfn dict-member>mimeType</dfn> <span class="idlMemberType">DOMString</span>
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</dt>

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