Aiortc-datachannel-only

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Media
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* Make RemoteStreamTrack emit an "ended" event, to simplify shutting down
media consumers.
* Add RemoteStreamTrack.readyState property.
* Handle timestamp wraparound on sent RTP packets.

Packaging
.........

* Add a versioned dependency on cffi>=1.0.0 to fix Raspberry Pi builds.

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Data channels
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* Optimize reception for improved latency and throughput.

Media
.....

* Add initial :meth:`RTCRtpReceiver.getStats()` and :meth:`RTCRtpReceiver.getStats()` coroutines.

Examples
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* `datachannel-cli`: display ping/pong roundtrip time.

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Media
.....

* Make it possible to add multiple audio or video streams.

* Implement basic RTP video packet loss detection / retransmission using RTCP NACK feedback.

* Respond to Picture Loss Indications (PLI) by sending a keyframe.

* Use shorter MID values to reduce RTP header extension overhead.

* Correctly shutdown and discard unused transports when using BUNDLE.

Examples
........

* `server` : make it possible to save received video to an AVI file.

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Peer connection
...............

* Add support for TURN over TCP.

Examples
........

* Add media and signaling helpers in `aiortc.contrib`.

* Fix colorspace OpenCV colorspace conversions.

* `apprtc` : send rotating image on video track.

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Media
.....

* Set PictureID attribute on outgoing VP8 frames.

* Negotiate and send SDES MID header extension for RTP packets.

* Fix negative packets_lost encoding for RTCP reports.

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Data channels
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* Numerous performance improvements in congestion control.

Examples
........

* `datachannel-filexfer`: use uvloop instead of default asyncio loop.