[asterisk-users] Help needed with ARI RTP externalMedia bridging please

[Jonathan H]

Very simply, I want to pipe some external audio into a channel (bridge)
using the externalMedia channel option.
Running Asterisk 18 on ubuntu, here's what I did to try and test things out:

open a console tab
vlc -vvv https://media-ssl.musicradio.com/LBCUK --sout
'#transcode{vcodec=none,acodec=ulaw,channels=1,samplerate=8000}:rtp{dst=127.0.0.1,port=5005}'

open another console tab
wscat -c
"ws://localhost:8088/ari/events?api_key=asterisk:asterisk&app=playback-example"

open another console tab
curl -v -u asterisk:asterisk -X POST "
http://localhost:8088/ari/channels/externalMedia?external_host=127.0.0.1:5005&channelId=musicChannel&format=ulaw&app=playback-example
"
curl -v -u asterisk:asterisk -X POST "
http://localhost:8088/ari/bridges/musicBridge?type=mixing"
then dial in from a phone
curl -v -u asterisk:asterisk -X GET "http://localhost:8088/ari/channels"
and note the new call channel ID
curl -v -u asterisk:asterisk -X POST "
http://localhost:8088/ari/bridges/musicBridge/addChannel?channel=<phone
channel from above>,musicChannel"

... and there is silence when I expected either music or at least some kind
of noise.

Is it something I'm doing wrong with the channel mixing, or with the
transcoding with vlc? Been battling this all day and could really use a
second pair of eyes on this.
Thanks.

(PS - of course, I would use the node SDK for live stuff, and not
"asterisk:asterisk" as username/password!)

Here's the VLC output - does "PCMU/8000 on port 5005 RTP/AVP 0" look
reasonable?

o=- 16401160996019665100 16401160996019665100 IN IP4 ip-172-31-37-244
s=Unnamed
i=N/A
c=IN IP4 127.0.0.1
t=0 0
a=tool:vlc 3.0.11
a=recvonly
a=type:broadcast
a=charset:UTF-8
m=audio 5005 RTP/AVP 0
b=AS:64
b=RR:0
a=rtpmap:0 PCMU/8000
a=rtcp:5006
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