#!/bin/busybox ash
set -euo pipefail

cd "$(dirname "$0")"

lecture=test_render
mkdir -p "$lecture"
rm "$lecture"/* || true

for file in *.mp4; do echo "file '$(realpath "$file")'" >>"$lecture/recording.txt"; done

function write_svg() {
	echo '<svg viewBox="0 0 1920 1080" width="1920" height="1080">'
	echo '  <rect fill="black" x="0" y="0" width="1920" height="1080"/>'
	echo '  <text x="960" y="540" fill="white" text-anchor="middle" dominant-baseline="hanging" font-family="Noto Sans">'
	echo "    $1"
	echo '  </text>'
	echo '</svg>'
}

write_svg Intro >"$lecture/intro.svg"
write_svg Outro >"$lecture/outro.svg"

set -x

ffmpeg \
	-hide_banner \
	-f concat \
	-safe 0 \
	-i "$lecture/recording.txt" \
	-af "pan=stereo|c0=c0|c1=c0,aformat=sample_rates=48000" \
	-c:v copy -b:a 128000 \
	"$lecture/recording.mp4"

ffmpeg \
	-hide_banner \
	-vaapi_device /dev/dri/renderD128 \
	-loop 1 -i "$lecture/intro.svg" \
	-filter_complex "[0]format=nv12,hwupload[v];aevalsrc=0:s=48000[a]" \
	-map "[v]" -map "[a]" \
	-c:v h264_vaapi -r 25 -t 3 -b:a 128000 \
	"$lecture/intro.mp4"

ffmpeg \
	-hide_banner \
	-vaapi_device /dev/dri/renderD128 \
	-loop 1 -i "$lecture/outro.svg" \
	-filter_complex "[0]format=nv12,hwupload[v];aevalsrc=0:s=48000[a]" \
	-map "[v]" -map "[a]" \
	-c:v h264_vaapi -r 25 -t 5 -b:a 128000 \
	"$lecture/outro.mp4"

ffmpeg \
	-hide_banner \
	-vaapi_device /dev/dri/renderD128 \
	-i "$lecture/intro.mp4" \
	-i "$lecture/recording.mp4" \
	-i "$lecture/outro.mp4" \
	-i "../assets/logo.svg" \
	-i "../assets/fastforward.svg" \
	-async 1 \
	-filter_complex "
			[1:v]trim=start=2:duration=8,setpts=PTS-STARTPTS[v_tmp0];
			[1:a]atrim=start=2:duration=8,asetpts=PTS-STARTPTS[a_tmp0];
			[0:v][0:a][v_tmp0][a_tmp0][2:v][2:a]concat=n=3:v=1:a=1[v_tmp1][a_tmp1];
			[v_tmp1]format=nv12,hwupload[final_v];
			[a_tmp1]anull[final_a]
		" \
	-map '[final_v]' -map '[final_a]' \
	-c:v h264_vaapi -rc_mode CQP -global_quality 22 \
	-c:a aac -b:a 128000 \
	"$lecture/$lecture.mp4"