#!/bin/bash
set -euxo pipefail

INTRO="$1"
RECORDING="$2"
OUTRO="${3:-intros/outro_ccbysa.mkv}"

START_SECONDS="$3"
STOP_SECONDS="$4"

DURATION_SECONDS=$(($STOP_SECONDS - $START_SECONDS))
FADEOUT_SECONDS=$(($DURATION_SECONDS - 1))

ffmpeg -i "$INTRO" \
  -ss $START_SECONDS -t $DURATION_SECONDS -i "$RECORDING" \
  -i "$OUTRO" -filter_complex \
  "[1:v:0]fade=t=in:st=0:d=0.2[x];[x]fade=t=out:st=$FADEOUT_SECONDS:d=1.0[y];\
  [1:a:0]afade=t=in:st=0:d=0.2[a];[a]afade=t=out:st=$FADEOUT_SECONDS:d=1.0[b];\
  [b]dynaudnorm[bd];\
  [0:v:0][0:a:0]\
  [y][bd]\
  [2:v:0][2:a:0]\
  concat=n=3:v=1:a=1\
  [v][a0]" \
  -map '[v]' -map '[a0]' \
  -c:a aac -b:a 192k \
  -c:v libx264 -threads 0 -pix_fmt yuv420p -crf 18 -profile:v high -level 4.1 -disposition default \
  -metadata:s:a:0 language=native \
  "rendered_recordings/$(basename -s .mp4 ${INTRO})_$(basename -s .mkv ${RECORDING})_COMBINED.mkv"