Bitrate is not equal targetbitrate

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Egor Larichev

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May 13, 2020, 5:43:41 PM5/13/20
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Could you please suggest :
1) Video bitrate:
at loopback: targetbitrate 4686399
at ffmpeg output:
frame= 1498 fps= 30 q=-1.0 size= 15616kB time=00:01:02.17 bitrate=2057.4kbits/s speed=1.24x

code for init video session:

function initVideoChannel() {

	const streamer = MediaServer.createStreamer();

	//Create new video session codecs
	const video = new MediaInfo("video","video");

	//Add h264 codec
	video.addCodec(new CodecInfo("h264",96));
	video.setBitrate(50000); //seems like doesn't work
	//Create session for video
	const session = streamer.createSession(video,{
		local  : {
			port: 5004
		},
		remote : {
			ip : "127.0.0.1",
			port: 8321
		}
	});

	return session
}

videoSession.getOutgoingStreamTrack().attachTo(incomingStream.getVideoTracks()[0]);



input.sdp

c=IN IP4 127.0.0.1
m=video 8321 RTP/AVP 96
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1

How to set bitrate fully passthrough, it speeds up just before 2500kbit ?

Sergio Garcia Murillo

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May 13, 2020, 5:48:01 PM5/13/20
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The media server will forward whatever media it receives, it doesn't transcode, so can't change bitrate. The setBitrate on the CodecInfo only works on webrtc SDP O/A, not on the streamer session

In chrome check chrome://webrtc-internals for the actual bitrate sent, 2mbps seems the correct bitrate for an h264 stream sent by webrtc.

Best regards

Sergio

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Egor Larichev

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May 13, 2020, 6:16:59 PM5/13/20
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Yes, u right. We have 2.5 there, in webrtc logs.
Just confused a little bit, why have see in logs ((

transport.on("targetbitrate", bitrate=>console.log("targetbitrate " + bitrate));

targetbitrate 5124277
targetbitrate 5137576
targetbitrate 5143224
targetbitrate 5116635
targetbitrate 5124991
targetbitrate 5133026
targetbitrate 5128975
targetbitrate 5143841
targetbitrate 5136366
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Screenshot from 2020-05-14 01-14-41.png

Sergio Garcia Murillo

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May 13, 2020, 6:18:19 PM5/13/20
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That is the bandwidth estimation calculated on the media server about how much bitrate it is available for sending to the browser.
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Egor Larichev

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May 13, 2020, 6:26:10 PM5/13/20
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Ok, thanks ! Maybe i will reach more then 2.5 when apply another profile for h264 )
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