2.2.11.7 RTCP Profile Specific Extension for Audio Healer Metrics

The RTCP profile specific extension for audio healer metrics is appended to the RTCP RR reports. The format of this extension is as follows. <29>


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Type

Length

SSRC

Concealed Frames

Stretched Frames

Compressed Frames

Total Frames

Reserved

Receive Quality State

FEC distance Request

Type (2 bytes): The extension type. Set to 0x0009 (9).

Length (2 bytes): The extension length in bytes, including this header. Set to 0x001C (28).

SSRC (4 bytes): The SSRC for which the audio healer metrics is being reported.

Concealed frames (4 bytes): The total number of concealed audio frames that have been generated during the call. A concealed frame is a frame of audio data that contains generated or reconstructed audio that is intended to conceal lost or missing audio. For this metric, each frame consists of 10 milliseconds of non-overlapping audio data with one or more frames that are encoded in each RTP packet.

Stretched frames (4 bytes): The total number of stretched frames that have been generated during the call. A stretched frame is a frame of audio data that is modified to require more time to play out than the original audio. For this metric, each frame consists of 10 milliseconds of non-overlapping audio data with one or more frames that are encoded in each RTP packet.

Compressed frames (4 bytes): The total number of compressed frames that have been generated during the call. A compressed frame is a frame of audio data that is modified to require less time to play out than the original audio. For this metric, each frame consists of 10 milliseconds of non-overlapping audio data with one or more frames that are encoded in each RTP packet.

Total frame (4 bytes): The total number of frames that have been generated during the call. For this metric, each frame consists of 10 milliseconds of non-overlapping audio data with one or more frames that are encoded in each RTP packet.

Reserved (2 bytes): Reserved for future extensions and SHOULD be set to zero (0). This MUST be ignored by the receiver.

Received quality state (1 byte): The received audio quality so far in the call. It MUST be set to one of the following values.

  • 0: Unknown quality.

  • 1: Good quality.

  • 2: Poor quality.

  • 3: Bad quality.

Other values MUST be mapped to "Unknown quality".

FEC distance Request (1 byte): The FEC distance requested by the receiver from the sender. It MUST be set to one of the following values:

  • 0: No FEC requested.

  • 1: FEC distance of 1 is requested.

  • 2: FEC distance of 2 is requested.

  • 3: FEC distance of 3 is requested.

Other values MUST be set to zero (0).