[FFmpeg-user] Unable to receive RTP payload type 97 without an SDP file describing it

[Mickael MONSIEUR]

Hello,

I try to make a low latency sound link with ffmpeg.

With MP3, it works:

Encoder:
ffmpeg -re -f alsa -i default:CARD=CODEC -acodec mp3 -ab 128k -ac 2 -f rtp
rtp://10.1.0.19:8000

Decoder:
ffplay rtp://127.0.0.1:8000

It works!

With libopus (better codec)

Encoder:
ffmpeg -re -f alsa -i default:CARD=CODEC -acodec libopus -ab 64k -ac 2 -f
rtp rtp://10.1.0.19:8000

Decoder:
ffplay rtp://127.0.0.1:8000

i have the error:

[rtp @ 0xb45004a0] Unable to receive RTP payload type 97 without an SDP
file describing it
Input #0, rtp, from 'rtp://127.0.0.1:8000':
  Duration: N/A, bitrate: N/A
Failed to open file 'rtp://127.0.0.1:8000' or configure filtergraph


ffplay version N-81350-g3282e31 Copyright (c) 2003-2016 the FFmpeg
developers
  built with gcc 4.9.2 (Raspbian 4.9.2-10)
  configuration: --arch=armel --target-os=linux --enable-ffplay
--enable-gpl --enable-libvorbis --enable-libopus --enable-libfdk-aac
--enable-libtwolame --enable-libmp3lame --enable-nonfree
--extra-cflags=-I/arm/include --extra-ldflags=-L/arm/lib --extra-libs=-ldl

Thanks,