From d575ec0a3ef3698873f61bcb03d38022acdd88e5 Mon Sep 17 00:00:00 2001
From: esche <esche@noreply.localhost>
Date: Thu, 6 Jul 2023 23:06:41 +0200
Subject: [PATCH] Complete rewrite

added mkv support
added support for multiple audio streams
added support for thumbnails that are in a separate video stream
added support for movies
---
 to_opus.sh | 71 +++++++++++++++++++++++++++---------------------------
 1 file changed, 36 insertions(+), 35 deletions(-)

diff --git a/to_opus.sh b/to_opus.sh
index 3381e97..d7cef48 100644
--- a/to_opus.sh
+++ b/to_opus.sh
@@ -35,45 +35,46 @@ extension="${extension##+([[:space:]])}"
 extension=${extension// /|}
 
 for file in **/*.@($extension); do
-	
-	#set a channel-dependent  bitrate for every audio stream
-	command=$(
-		ffprobe "$file" -v 0 -show_entries stream=channels,bit_rate -select_streams a -of compact=p=0:nk=1:s="\ " |
-		awk -v file="$file" -v file_output="${file%.*}.opus" '
-			BEGIN{
-				ORS=" ";
-				print "ffmpeg -i \""file"\" -map 0:a -c:a libopus"
-			}
-			{	# https://wiki.xiph.org/Opus_Recommended_Settings
-				if($1==1) {
-					if($2>=64000) print "-b:a:"NR-1" 64k"
-				}
-				else if($1==2) {
-					if($2>=128000) print "-b:a:"NR-1" 128k"
-				}
-				else if($1<=6) {
-					if ($2>=256000) print "-b:a:"NR-1" 256k"
-				}
-				else if ($2>=450000) print "-b:a:"NR-1" 450k"
-			}
-			END{
-				print "\""file_output"\" -v info -hide_banner"
-			}')
 
+	# array over the number of channels of all streams
+	readarray -t channels <<<"$(ffprobe -v error -select_streams a -show_entries stream=channels -of compact=p=0:nk=1 "$file")"
+	# array over the bitrates of all streams
+	readarray -t bitrate <<<"$(ffprobe -v error -select_streams a -show_entries stream=bit_rate -of compact=p=0:nk=1 "$file")"
+	# number of audiostreams
+	audiostreams=${#channels[@]}
+	# check if it contains video streams (Thumbnails etc. will be ignored)
+	isvideo=$(ffprobe -v error -select_streams V -show_entries stream=codec_type "$file")
+	use_mkv="false"
+	command="ffmpeg -i \"$file\""
 
-	is_video=$(ffprobe -i Hair.m4v -v fatal -select_streams V -show_entries stream=codec_type)
-	if [[ -n "$is_video" ]]; then
-		echo "$file contains a video stream and will not be converted"
-
-		#an Example for converting the audiostreams in a container while copying subtitles and videostreams.
-		#ffmpeg -i Hair.m4v -map 0:a -map 0:s -map 0:v -c:a libopus -c:v copy -c:s copy Hair.mkv -hide_banner -v info
-
-		#for extracting the audiostreams of a video file just use "eval "$command"".
-		#it is recommended to check the result before deleting the original file.
-	else
-		eval "$command" #&& rm "$file"
+	# use mkv, if multiple audiostreams exists or it is a videofile
+	if [[ ${#channels[@]} -gt 1 || -n "$is_video" ]]; then
+		command="$command -map 0 -map -0:d -c copy -c:a libopus"
+		use_mkv="true"
 	fi
 
+	# set a channel dependend bitrate for every audio stream
+	# https://wiki.xiph.org/Opus_Recommended_Settings
+	# to use ffmpegs default just comment out this block
+	for ((index=0; index<audiostreams;index++)); do
+		if [[ ${channels[index]} -eq 1 ]]; then
+			if [[ $bitrate == 'N/A' || ${bitrate[index]} -gt 64000 ]]; then command="$command -b:a:$index 64k"; fi
+		elif [[ ${channels[index]} -eq 2 ]]; then
+			if [[ $bitrate == 'N/A' || ${bitrate[index]} -gt 128000 ]]; then command="$command -b:a:$index 128k"; fi
+		elif [[ ${channels[index]} -lt 6 ]]; then
+			if [[ $bitrate == 'N/A' || ${bitrate[index]} -gt 256000 ]]; then command="$command -b:a:$index 256k"; fi
+		elif [[ $bitrate == 'N/A' || ${bitrate[index]} -gt 450000 ]]; then command="$command -b:a:$index 450k"; fi
+	done
+
+	echo "$use_mkv"
+
+	if [[ $use_mkv = "true" ]]; then
+		command="$command -v info -hide_banner \"${file%.*}.mkv\""
+	else
+		command="$command -v info -hide_banner \"${file%.*}.opus\""
+	fi
+
+	eval "$command" #&& rm "$file"
 done
 
 exit 0