#!/bin/sh
# MediaMTX runOnReady hook (runs INSIDE the mediamtx container; busybox sh + wget + ffmpeg from the -ffmpeg image).
# Env from MediaMTX: MTX_PATH (user/Title). From compose: LIVE_WEBHOOK_URL, LIVE_HOST.
# 1. optional Discord "is live" notice
# 2. WebRTC audio mirror: browsers cannot receive AAC over WebRTC (MediaMTX forwards Opus/G711/G722/LPCM only), and
#    OBS sends AAC. For every stream whose audio is not already Opus, copy the video and transcode the audio to Opus
#    into the sibling path "<user>/<Title>.webrtc". The live portal plays that path over WebRTC; recordings, HLS and
#    the Discord notice stay on the original. Mirrors are published from 127.0.0.1 inside this container only, which
#    is the only publisher dumpd accepts for ".webrtc" paths. Audio-only transcode: a few % of one core per stream.
# MediaMTX kills this process when the source path goes away.
case "$MTX_PATH" in *.webrtc) exit 0 ;; esac
u="${MTX_PATH%%/*}"; t="${MTX_PATH#*/}"
if [ -n "$LIVE_WEBHOOK_URL" ]; then
  wget -q -O /dev/null --header="Content-Type: application/json" \
    --post-data="{\"content\":\"🔴 **$u** is live: $t — https://$LIVE_HOST/\"}" "$LIVE_WEBHOOK_URL" 2>/dev/null &
fi
# which audio does the source carry? (API on loopback; "Opus" needs no mirror, no audio needs no mirror)
tracks=""
for i in 1 2 3 4 5; do
  tracks=$(wget -q -O - "http://127.0.0.1:9997/v3/paths/get/$MTX_PATH" 2>/dev/null) && [ -n "$tracks" ] && break
  sleep 1
done
case "$tracks" in
  *Opus*) exit 0 ;;
  *"MPEG-4 Audio"*|*"MPEG-1 Audio"*|*G711*|*G722*|*LPCM*|*AC-3*) ;;
  *) exit 0 ;;                                   # no (recognised) audio: nothing to mirror
esac
echo "event=mirror stream=$MTX_PATH target=$MTX_PATH.webrtc audio=opus"
n=0
while [ $n -lt 10 ]; do                          # retry: the source may not be readable for the first second
  ffmpeg -nostdin -hide_banner -loglevel warning -fflags nobuffer -flags low_delay \
    -rtsp_transport tcp -i "rtsp://127.0.0.1:8554/$MTX_PATH" \
    -map 0:v:0 -map 0:a:0 -c:v copy -c:a libopus -b:a 128k -ar 48000 -ac 2 -application lowdelay -frame_duration 20 \
    -f rtsp -rtsp_transport tcp "rtsp://127.0.0.1:8554/$MTX_PATH.webrtc"
  n=$((n+1)); sleep 2
done