# ffmpeg custom utilities
#
# To use:
#  source ffmpeg_utils.sh
#
# URL: https://gist.github.com/jaekookang/6a5829e00f38ed01da224076ca4960d9
#
# 2021-11-25 first created jaekoo kang

function ffmpeg_mkv_mp4() {
	# Convert mkv to mp4
	#
	# - Usage: ffmpeg_mkv_mp4 INPUT.mkv outOUTPUTput.mp4
	#
	# - Command: ffmpeg -i INPUT.mkv -map 0 OUTPUT.mp4
	
	ffmpeg -i $1 -map 0 $2
}

function ffmpeg_mka_mp3() {
	# Convert mka to mp3
	#
	# - Usage: ffmpeg_mka_mp3 INPUT.mka OUTPUT.mp3
	#
	# - Command: ffmpeg -i INPUT.mka OUTPUT.mp3
	ffmpeg -i $1 $2
}

function ffmpeg_mka_wav() {
	# Convert mka to mp3
	#
	# - Usage: ffmpeg_mka_wav INPUT.mka OUTPUT.wav
	#
	# - Command: ffmpeg -i INPUT.mka OUTPUT.wav
	ffmpeg -i $1 $2
}

function ffmpeg_resize_width() {
	# Specify the Width To Retain the Aspect Ratio
	#
	# - Usage: ffmpeg_resize_widdth INPUT.mp4 OUTPUT.mp4 320
	#
	# - Command: ffmpeg -i input.mp4 -vf scale=320:-1 output.mp4
	#
	# - Note:
	# 	- $1: input file
	#   - $2: output file
	#   - $3: target width (int)
	ffmpeg -i $1 -vf scale=$3:-1 $2
}

function ffmpeg_resize_height() {
	# Specify the Height To Retain the Aspect Ratio
	#
	# - Usage: ffmpeg_resize_height INPUT.mp4 OUTPUT.mp4 320
	#
	# - Usage: ffmpeg -i input.mp4 -vf scale=-1:720 output.mp4
	#
	# - Note:
	# 	- $1: input file
	#   - $2: output file
	#   - $3: target width (int)
	ffmpeg -i $1 -vf scale=-1:$3 $2
}

function ffmpeg_reduce() {
	# Reduce mp4 file size 
	#
	# - Usage: ffmpeg_reduce INPUT.mp4 OUTPUT.mp4
	#
	# - Command: ffmpeg -i INPUT.mp4 -vcodec h264 -acodec mp3 -crf 28 OUTPUT.mp4
	#
	# - Note:
	# 	- both video and audio stream are assumed

	ffmpeg -i $1 -vcodec h264 -c:a copy -crf 28 $2
}

function ffmpeg_extract_audio() {
	# Extract audio stream from mp4 file
	#
	# - Usage: ffmpeg_extract_audio INPUT.mp4 OUTPUT.mp3
	#
	# - Command: ffmpeg -i INPUT.mp4 -q:a 0 -map OUTPUT.mp3
	ffmpeg -i $1 -q:a 0 $2	
}

function ffmpeg_combine_video_audio() {
	# Combine/merge video with audio
	#
	# - Usage: ffmpeg_combine_video_audio VIDEO.mp4 AUDIO.mp3 OUTPUT.mp4
	#
	# - Command: ffmpeg -i video.mp4 -i audio.wav -c:v copy -c:a aac output.mp4
	ffmpeg -i $1 -i $2 -c:v copy -c:a aac $3
}