matrixfurry.com
Various scripts that I maintain
extract-m4a (new script)
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scripts/extract-m4a.nu
+88
scripts/extract-m4a.nu
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#!/usr/bin/env nu
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# SPDX-License-Identifier: AGPL-3.0-only
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# Copyright (c) 2025 Shiloh Fen <shiloh@shilohfen.com>
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use std log
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# Extract audio from a m4a file to the codec's native container
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def main [
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path: path
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--rm # Remove the original file after conversion
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] {
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let path = $path | path expand
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match (ls -D $path).0.type {
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"dir" => {
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let files = ls $path
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| get name
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| where $it ends-with ".m4a"
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let files_len = $files | length
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log info $"Extracting ($files_len) files."
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$files | par-each {|file|
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extract-file $file
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if $rm {rm $file}
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}
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log info $"Extracted ($files_len) files."
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}
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"file" => {
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extract-file $path
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if $rm {rm $path}
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}
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_ => (error make {
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msg: "Invalid path"
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label: {
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text: $"Invalid path: ($path)"
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span: (metadata $path).span
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}
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})
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}
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}
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def extract-file [file: path] {
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let file = $file | path expand
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let parsed_path = $file | path parse
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log info $"Extracting `($file)`"
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if $parsed_path.extension != "m4a" {
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error make {
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msg: "Format not supported"
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label: {
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text: $"Unsupported format: \"($parsed_path.extension)\""
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span: (metadata $file).span
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}
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help: "This tool currently only supports M4A."
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}
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}
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let codec = ffprobe -v quiet -select_streams a -show_entries stream=codec_name -of csv=p=0 $file | split row ","
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# Args:
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# -v quiet -> Only print result
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# -select_streams a -> Select only audio streams, in case there is album artwork or a video embedded as a stream
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# -show_entries stream=codec_name -> Get codec
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# -of csv=p=0 -> print comma-seperated list with no headers
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if ($codec | length) > 1 {
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error make {
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msg: "Too many audio streams"
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label: {
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text: $"Contains more than 1 audio stream: ($codec | length)"
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span: (metadata $file).span
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}
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help: "This tool can currently only handle a single audio stream"
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}
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}
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let codec = $codec.0
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let output: path = $"($parsed_path.parent)/($parsed_path.stem).($codec)"
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ffmpeg -v quiet -i $file -c:a copy -vn $output
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# Args:
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# -c:a copy -> Copy codec
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# -vn -> No video
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log info $"Extracted `($file)` to `($output)`"
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}