Tvheadend

I've tried the same, sadly with the same result. I guess the problem is, that it's still in a container and not just an audio stream. You could try to request a feature for a container-less, single stream transcoder option, maybe someone of the developers still uses this archaic medium and has a heart for us :D

/hp

I found a solution for this. Use "IPTV remuxer for tvheadend", normally used as input for tvh but can also be used at the output with some modifications...

https://github.com/Jalle19/node-ffmpeg-mpegts-proxy

Change in options.js

var getOutputAvconvOptions = function(source) {
        var options = [
/*              '-vcodec', 'copy',*/
                '-acodec', 'copy',
                '-metadata', 'service_provider=' + source.provider,
                '-metadata', 'service_name=' + source.name,
/*              '-f', 'mpegts'*/
        ];

and in node-ffmpeg-mpegts-proxy.js change to mpeg output insted of mpegts

// Tell the client we're sending MPEG data
  response.writeHead(200, {
    'Content-Type': 'audio/mpeg'
  });

and in sources.json e.g.

       {
                "name": "R1",
                "provider": "BBC",
                "url": "/BBC_R1.mp2",
                "source": "http://server1a:9981/stream/channelnumber/3002",
    "avconvOptions": {
                        "input": [
     ],
                        "output": [
                                "-f", "mp2" 
                        ]
                }

        },

An in LMS:

http://server1a:9128/BBC_R1.mp2

Works great, 192 kbit/s instead of lousy 48 kbit/s...