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Webrtc delay from a rtmp live stream encoded using FFmpeg


ThibaultOber
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Hello, 

I am currently running a c++ application which emit a rtmp live stream using FFmpeg and libopenh264 as the encoder. This rmtp live stream then pass through antmedia server which convert it to a webrtc live stream.

I am following this guide to reduce delay: Minimizing the initial delay | VideoKit (iosvideokit.com)

I set those specific parameters:

- reduce the Iframe interval with the gop parameter to 1 every five frame (gop_size = 5)

- reduce the probe size parameter to 32 (Maximum number of bytes read from input in order to determine stream properties.)

- reduce the maxAnalyseDuration to 32 (Maximum duration (in AV_TIME_BASE units) of the data read from input in avformat_find_stream_info())

I am still noticing a 12 seconds delay inside the html viewer from the antmedia interface. When I am reading the log I saw that antmedia are reencoding the stream using libopenh264.

Is there some official guidelines to reduce delay from a rtmp live stream to a webrtc application ?

 

Here are the logs from the antmedia platform also attach in log format.

image.thumb.jpeg.aa94b92bf867dee121e20bb4799d47e0.jpeg

 

I saw the gopsize getting updated to 60fps, so the video is getting re-encoded. Is there a way to stop this process.

Latency is a huge deal in our application, thank you for your time.

ant-media-server.log

Edited by ThibaultOber
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Webrtc does not support ACC audio encoding so AMS transcode ACC to Opus. Can you plese try setting the key frame interval to once every 2 sec.can you try setting the encoder speed as veryfast.

Edited by usama
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you can refer this

ffmpeg -re -i 'video.mp4'  -c:v libx264 -b:v 1600k -preset ultrafast -b 900k -c:a aac -b:a 128k -s 1920x1080 -x264opts keyint=50 -g 25 -pix_fmt yuv420p -f flv rtmp://stream.serverok.in/LiveApp/225873992721868053400782

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