Extracting Apple’s iOS audio sounds

I wanted to use some of Apple’s iconic audio sounds in a project, here’s how I did it.

Extracting the audio files

The first thing was to extract the raw audio files from iOS.

On a mac this process was pretty simple.

• download the .ipsw files from a site like IPSW Downloads
• extract the correct .dmg which contains the files
• navigate to System/Library/Audio/UISounds where the files are located

This resulted in around 300 individual audio files.

Using these files

Worth noting is that Apple use their own proprietory Core Audio Format .caf file format which can be played using VLC.

My aim was to have an easy way of listening through them to identifying the ones I needed.

This turned out to be a four step process

1. convert the audio format
2. generate videos showing filenames
3. compile an index of these videos
4. concatenate them together

1. Convert the audio format

I used FFMPEG for this

Copy#!/bin/bash

mkdir ./mp3/

for path in ./caf/*.caf; do
  file=${path##*/}
  ffmpeg -i "$path" -c:a mp3 -strict -2 "./mp3/${file%.*}.mp3"
done

Copy#!/bin/bash

mkdir ./mp3/

for path in ./caf/*.caf; do
  file=${path##*/}
  ffmpeg -i "$path" -c:a mp3 -strict -2 "./mp3/${file%.*}.mp3"
done

Turns out this was necessary because of the .caf format¹ and audio sync issues.

… time is measured depending on the bitrate when importing aac files:

Estimating duration from bitrate, this may be inaccurate

2. Generate videos showing filenames

Again, using FFMPEG. The video includes a histogram of the audio and the filename.

Copy#!/bin/bash

mkdir ./mp4/

for path in ./mp3/*.mp3; do
  file=${path##*/}
  ffmpeg -i "$path" -s hd1080 -filter_complex "[0:a]ahistogram,format=yuv420p,drawtext=text='${file}':x=(w-text_w)/2:y=(h-text_h)/2:fontfile=./font.otf:fontsize=36:fontcolor=white" -c:v libx264 "./mp4/${file%.*}.mp4"
done

Copy#!/bin/bash

mkdir ./mp4/

for path in ./mp3/*.mp3; do
  file=${path##*/}
  ffmpeg -i "$path" -s hd1080 -filter_complex "[0:a]ahistogram,format=yuv420p,drawtext=text='${file}':x=(w-text_w)/2:y=(h-text_h)/2:fontfile=./font.otf:fontsize=36:fontcolor=white" -c:v libx264 "./mp4/${file%.*}.mp4"
done

Here is an example video generated.

Resources

FFMPEG

• Official FFmpeg Docs
• H.264 Video Encoding Guide
• Concatenating media files
• Show Filename in Video (fmpeg - drawtext)
• Adding silent audio in ffmpeg
• FFMPEG - video with timer
• Text on video ffmpeg

Command line scripting

• How do I remove the file suffix and path portion from a path string in Bash?
• Execute ffmpeg command in a loop

Audio sync issues

• FFMPEG concat video and audio out of sync
• FFMPEG concat makes video async over time
• Non-monotonous DTS in output stream when concat videos using ffmpeg
• FFMPEG is generating an out-of-sync audio/video file
• FFMPEG concatenate videos with audio not synched