Mac OS X: some audio engineering apps and tools

These are in addition to: FFmpeg: command line and GUI audio/video conversion tool: audio references

Most are known to run on Mac OS X Mountain Lion 10.8.5 as of 2013.


- FLAC tools: official command line tools for FLAC format.

- X Lossless Decoder (XLD): super little free GUI app for Mac OS X, can handle FLAC and ALAC and some other lossless formats, as well as converting from say FLAC to lossy formats like MP3 or AAC.

- Free Audio Converter (FREAC) GUI app: free audio converter and CD ripper. Features MP3, MP4/M4A, WMA, Ogg Vorbis, FLAC, AAC, and Bonk format support, integrates freedb/CDDB, CDText and ID3v2 tagging.

- Max: CD ripper and encoder that supports FLAC and some other formats.

Sound editors

- If I want to do anything exciting involving my own music I use the absolutely awesome Ableton Live for recording, editing, composition, and mastering. (BTW Ableton Live 9 supports multitrack recording up to 32-bit/192 kHz.) I can be engaged for professional audio services: visit Ableton Live (audio).

- Sometimes for post-processing or certain tasks I also use the audio editing in Final Cut, and I likewise offer professional media services for it: visit Final Cut video and audio editing and production.

But sometimes it is nice to be able to load a simpler audio editor for a quick fade-in/out or normalisation job, or just to make a quick recording.

- Audacity is a free, open-source, cross-platform audio editor for Mac, GNU/Linux Windows etc. It's not the world's best audio editor (especially not for MP3 or AAC because it imports, processes, then reexports with a small quality loss rather than say direct MP3 editing), but it has lots of FX and plugins and is sufficient for experiments, quick edits, and some post-processing, as well as wave analysis. As of Nov 2013 on OS X Mountain Lion 10.8.5, I find it far more stable than it used to be. Given that it's free, there's an awful lot that you can do with Audacity.

- To use Audacity with MP3 you will need to also install the LAME MP3 encoder, it's easy.

Internally Audacity works in uncompressed audio in 32-bit floating point by default, and offers up to 96kHz sample rate. You may simply import, edit, then export changes (losing edits), or save edited audio in its native AUP multi-file project folder format. In order to play the results in other programs, you must always export to another well-known format, and it supports nearly every format you will ever need.

- There is an unofficial Wave Stats plugin for Audacity that performs excellent wave analysis over regions of about 30s length, which is enough for you to explore the difference between dBFS RMS and max peaks.

To learn how to install Plugins for Audacity (and most other audio editors) on Mac OS X visit: Mac OS X: audio engineering plugins.

- From Rogue Amoeba for $32: Fission:

'Crop and trim audio, paste in or join files, or just rapidly split one long file into many. Fission is streamlined for fast editing. Plus, it works without the quality loss caused by other editors, so you can get perfect quality audio even when editing MP3 and AAC files. If you need to convert formats, Fission can do that too! You can rapidly export or batch convert files to the MP3, AAC, Apple Lossless, FLAC, AIFF, and WAV formats.'

I tried the free demo for file splitting on silences, not bad.

Here are some other editors I have not yet tried, but they might be worth a go:

- TwistedWave is available for Mac ($79.90), iPhone / iPad ($9.99) and online. TwistedWave for Mac is available as a fully functional 30 day demo. Can handle audio at a resolution up to 32-bit and 192 kHz sampling rate. Includes batch processing with silence detection for splitting long recordings into many files. Can perform pitch correction, pitch shift, and time stretch.

- NHC Software offer the Master's edition of WavePad for $59.95 (includes VST plugins and SFX library), however:

'A free version of WavePad audio editing software is available for non-commercial use only. The free version does not expire and includes most of the features of the normal version. If you are using it at home, you can download the free version here. You can always upgrade to the master's edition at a later time, which has additional effects and features for the serious sound engineer.'

Supports sample rates from 6 to 96kHz, stereo or mono, 8, 16, 24 or 32 bits.

There are dozens of other sound editors for Mac, but as far as I can tell, unless you are working on some real original music composition with something truly professional like Ableton, all you need is Audacity (free).


- Well obviously iTunes: plays most formats including WAV, AIFF, MP3 and AAC, likes compressed lossless ALAC, but does not play lossless compressed FLAC directly (yet). But that is not so bad because ...

- Fluke app: small OS X utility for listening to FLAC files within iTunes, without having to convert anything.

- QuickTime Player: although mainly known as a video player, is very useful for playing audio files (with a simple audio player GUI mode), and it also has a nice file info display with bit rates, sample rates etc. QuickTime is especially useful when you don't want to pollute your iTunes library with audio test files. Just right click and "open with .." then choose QuickTime Player instead of iTunes (or even set QuickTime Player as default for that audio file kind). However, as far as I can tell, QuickTime Player 10.2 still does not play FLAC.

- From Mac Software to play and convert FLAC:

The following software will play FLAC files without any requirement for modification - simply download, install and start using the current version.

- Cog:

- Play:

- VLC:

- Songbird:

- Bigasoft Audio Converter:

- From Audiofile Engineering for $US 19.99 Fidelia: Premium Music Player:

Fidelia is a high-definition audio player for sophisticated music lovers. With support for all contemporary audio file formats and an elegant interface that focuses exclusively on music, it gives users the power and the freedom to organize, customize and savor their digital music collection at the highest possible fidelity in any circumstance. If you've invested in premium audio hardware, you should have the best audio software.

Plays FLAC. Has adjustable real-time dithering.

- From Sbooth for $US 33 comes Decibel:

'Decibel is an audio player tailored to the particular needs of audiophiles. Decibel supports all popular lossless and lossy audio formats including FLAC, Ogg Vorbis, Musepack, WavPack, Monkey's Audio, Speex, True Audio, Apple Lossless, AAC, MP3, WAVE and AIFF. For lossless formats such as FLAC and WAVE, and for Ogg Vorbis and specially tagged MP3 files, Decibel supports gapless playback with seamless transitions between tracks. Decibel processes all audio using 64-bit floating-point precision, providing the highest possible playback quality for files sampled at all bit depths.'


Pro Level is a simple little $US 5 app with various VU-like digital monitors and some nice simple peak and clip hold settings, but you will need SoundFlower to shunt whatever stream your are targeting back through as an audio input source before it will see it (compare with Audio Hijack below, which you can also use to monitor system audio or any application's sound output directly).

Spectre: real-time Studio Multi-analyzer from Audiofile Engineering for $US99:

'Spectre is a multi-instrument real-time audio analyzer for Mac OS X. Designed in Cocoa from the ground up, Spectre proudly takes advantage of Quartz, OpenGL, CoreAudio, and other solid OS X interface features. Flexibility & Precision. Spectre focuses squarely on live audio analysis by offering 17 different multi-channel and multi-trace meters. Each meter can have any number of traces or indicators, and each trace can have it's own number of input channels, gain, mixing, filtering, ballistics and color (including transparency).'


- A likely "must have" for audio fun on a Mac is SoundFlower:

'Free Inter-application Audio Routing Utility for Mac OS X. Soundflower is a Mac OS X (10.2 and later) system extension that allows applications to pass audio to other applications. Soundflower is easy to use, it simply presents itself as an audio device, allowing any audio application to send and receive audio with no other support needed.

How To Use Soundflower

Soundflower presents itself as one of two audio devices (2ch / 16ch). The 2-channel device is sufficient for most situations. To send the output of one application to another, select Soundflower as the output device in the first application and Soundflower as the input device within the second application. If an application does not allow you to specify audio devices, you can make Soundflower the default input or output device inside the Sound panel in the System Preferences, or with the Audio MIDI Setup utility application. The 16-channel device is provided for more complex routing situations, and can be used with more than two applications simultaneously if the applications support audio routing to any channel, as Max/MSP does.'

But some of the functionality you might achieve with SoundFlower is more easily achieved out-of-the box with a good "hijacker".

Audio stream hijackers

"Exploring" and recording your (Mac) computer system's and applications' music sources (including online radio):

- Audio Hijack Pro (at around $US 32) is an absolutely super bit of software. You can record nearly any source (including any application) on your Mac, or full system audio. You can record Skype, Facetime, or anything you choose to "hijack", such as a particular web browser playing online radio. (Oops, I said it.) It has a very rich set of FX too, including tapping into all available VST and Apple FX, and you can customise nearly everything, including recording format, bit-rates, levels, schedule recordings, split recordings on-the-fly according to silence detection (with adjustable parameters). You can even use it to shunt audio around your system bus. Amazing !

- Also by Rogue Amoeba there is a new mini-version called Piezo, which unlike Audio Hijack Pro passes the restrictions to enter the Apple App Store. It enables you to record audio from any application, but you have restart the app every time after hijacking before a recording can start.

- To be fair I should also mention SoundTap (Mac and Win) from NHC Software, who also have a super kit of other audio apps. It is however not nearly as powerful as Audio Hijack Pro, but it's enough to tap a bit of your computer's sound quickly.

- And also Snowtape:

'Listen to internet radio. Record the music. Schedule radio shows. Edit songs and get album artwork. Export to iTunes.'

Hang on. Record the music ? From internet radio ? Ooh aah, that's naughty !

- And also Fstream for Mac. 'Listen to and record online radio easily'. Also available as an iPhone radio listening app.

No wonder so many online radio streams deliberately keep under 128kbps !

Some other audio apps and tools

- patch-based real-time audio and video synthesis. From the Max/MSP family. PureData is amazingly powerful and very clever. See also the Puredata synthesis zone for some examples. I am a huge fan of the PureData project; May Miller Puckette and the PureData/GEM community be blessed.

To see how I use PureData synthesise music and visuals from triaxial accelerometers to make real-time body music (gestural synthesis) see the Drancing project.

- MP3-Info is a very handy little app:

'MP3-Info is a clever companion that helps you organize your music collection. It is essentially a Plug-in for the Finder and iTunes. MP3-Info displays valuable information about audio files, such as their duration, the bitrate, important MP3-Tags, such as the artist, the title of the song, lyrics, cover art, and some more. That saves you a lot of time managing your song collection. It also shows these information for AAC files created by iTunes, and WAV, and AIFF files.'

- I haven't tried it yet, but AudioFinder sounds amazing. Can preview any audio file and give metadata and stats on any audio file direct in the Mac Finder.

- From TuneSweeper:

'Quickly find and remove all duplicates in your iTunes library. Remove missing iTunes files. Add additional music on your computer into iTunes.'

- FREE from AudioSlicer:

'AudioSlicer is a Cocoa GUI application for Mac OS X that finds all silences in an audio file and allows you to split it into several smaller audio files and to name/tag them properly. For now only MP3 is supported but other audio formats may be added in the future.'

FFmpeg: command line and GUI audio/video conversion tool: audio references

FFmpeg can be used for both video and audio conversion and stream manipulation; this page records some useful links for audio work with FFmpeg.

The reality is that I mostly use other Mac GUI tools like XLD (X Lossless decoder), Freac, Max etc. for converting, but I do find ffmpeg command line useful for tricky situations, and you can use it to make a nice and very quick audio statistics command line tool for checking RMS values and peaks in files (so that you can then decide whether or not they should be normalised, without having to load them in a sound editing app).

Command line ffmpeg

Command line 'ffmpeg' for Mac can be installed using MacPorts. I got it working OK on Mac OS X Mountain Lion, but you should at least be a bit UNIX savvy to try this. You will also need the LAME MP3 Encoder port if you want to deal with MP3.

$ sudo port install ffmpeg

$ sudo port install lame

(As always with mac ports, don't be scared to use that -f (force) option if you upgraded your os recently !)

FFmpegX is a rather clunky but nevertheless very powerful GUI for FFmpeg for Mac OS X. For some reason I could not get it to work with FLAC lossless compression files, but the command line version works with FLAC.

Useful FFmpeg links for audio:

- Audio options

- Video and audio file format conversion

- Rodrigo Polo's FFmpeg cheat sheet.

- FFmpeg basics for beginners

- An amazingly comprehensive 6-part series from 2011/2012 by Fabio Sonnati FFmpeg: the swiss army knife of Internet Streaming.

Supported audio types. You can also use command line:

$ffmpeg -codecs
$ ffmpeg -formats

Making a simple audio statistics analyzer

Store the following in a file at ~/bin/@ffmpeg-statistics:

ffmpeg -i "$1" -filter:a "volumedetect" -vn -f null /dev/null

Make sure you make it executable with:

chmod +x ~/bin/@ffmpeg-statistics'.

And do "quote" your audio file name if it contains spaces:

@ffmpeg-statistics "my audio file.mp3"

Output is like:

Duration: 00:05:32.43, start: 0.000000, bitrate: 128 kb/s
Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 128 kb/s
Output #0, null, to '/dev/null':
encoder : Lavf55.12.100
Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (mp3 -> pcm_s16le)
size=N/A time=00:05:32.43 bitrate=N/A
video:0kB audio:57263kB subtitle:0 global headers:0kB muxing overhead -100.000038%
[Parsed_volumedetect_0 @ 0x7f8fa8412d00] n_samples: 29318494
[Parsed_volumedetect_0 @ 0x7f8fa8412d00] mean_volume: -17.1 dB
[Parsed_volumedetect_0 @ 0x7f8fa8412d00] max_volume: -1.4 dB
[Parsed_volumedetect_0 @ 0x7f8fa8412d00] histogram_1db: 12
[Parsed_volumedetect_0 @ 0x7f8fa8412d00] histogram_2db: 583
[Parsed_volumedetect_0 @ 0x7f8fa8412d00] histogram_3db: 9111
[Parsed_volumedetect_0 @ 0x7f8fa8412d00] histogram_4db: 42170

There are lot sof example of the use of FFmpeg for command line processing, including using the new EBU R128 loundness filter "ebur128", at: A summary of a review of music levels for broadcasting, personal use, recording and mastering, including the new LOUDNESS measures.

Audio engineering test/sample file resources, and online generators and online audio tests

Some handy audio test file and test generator resources

- AudioCheck - Internet's largest collection of Sound Tests, Audio Test Tones, and Tone Generators. Online and Free!

- AudioCheck: Pink noise test tones. Includes excellent description of pink noise principles. Pink noise sample files generated using wavTones' professional grade Pink Noise Generator. Download Pink Noise CD Quality WAV.

- AudioCheck: High Definition Audio test files, but only it seems "high definition" in the sense of sample rates higher than 44.1kHz. Frequency sweeps, chirp tones, white noise, pink noise. Includes Pink Noise: 96kHz, -3dBFS, 30s, 5.6MB (WAV) BUT ONLY 16-bit.

- AudioCheck: dynamic test tones: A series of pink noise files at full scale then a given number of dB below, down to 72dB and then Mute:

'Nowadays, much emphasis is placed on 24-bit recordings, with a dynamic range exceeding 140dB. Use these test tones to realize how 16-bit supersedes by far the dynamic range offered by your listening environment.

"At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need? (a quote from the internet)." '

I downloaded them and performed tests on them as reported here: [node/3247].

- Ten-minute clips of white noise, pink noise and Brownian noise. Recorded in stereo at a 24-bit 48-kHz rate. Synthesized with Sound Forge Software. Available in 24bit FLAC, Ogg Vorbis, 64Kbps MP3, and VBR MP3.

- Sound tests and clips: WAV 48KHz, 16bit stereo. Examples: LRMonoPhase, piano, some organ sounds. Maybe more useful Pink Noise, 48k/32Float, Stereo, 3.7MB.

- A very useful list of Free 24/96 Downloads.

- Label where you can download sample FLAC and WAV in 24 Bit / 96 kHz & 24 Bit / 192 kHz files

- LINN Records test files: 16-bit and 24-bit ALAC and FLAC, 320kbps MP3 (sample rates not stated).

- Sound Keeper Recordings Format comparison: includes 16-bit/44kHz, 24-bit/96kHz, 24-bit/192kHz zipped WAV files.

- Steinway and Sons: Three excerpts from Franz Liszt's Mephisto Waltz No. 1, in Original: 24 bit / 96 kHz (103 MB) vs. CD quality: 16 bit / 44.1 kHz (32 MB).

- HIRES FLAC testbench downloads: Mozart, Beethoven etc. FLAC 24-bit/192kHz, FLAC 24-bit/96kHz ..

Listening and format comparison tests (for fun and humility)

- Up to the challenge? Do 320kbps mp3 files really sound better? Take the test!

- AudioCheck: Blind Listening Tests. A heap of truly humbling sound tests that some self-proclaimed audiophiles would be too scared to try. Try them with your cheapest headphones possible to thwart the tests completely, or do it properly and use very expensive audiophile speakers and best quality equipment .. and get almost exactly the same result.

Monty Montgomery's high definition and ultrasonic audio test files

This is a super article 24/192 Music Downloads ... and why they make no sense including ultrasonic "intermod" tests:

'a 30kHz and a 33kHz tone in a 24/96 WAV file, a longer version in a FLAC, some tri-tone warbles, and a normal song clip shifted up by 24kHz so that it's entirely in the ultrasonic range from 24kHz to 46kHz ..'Assuming your system is actually capable of full 96kHz playback, the .. files should be completely silent with no audible noises, tones, whistles, clicks, or other sounds. If you hear anything, your system has a nonlinearity causing audible intermodulation of the ultrasonics.'

Well I played the normal song clip shifted up by 24kHz [10 sec WAV] and on my MacBook Pro 17" early 2008 (and listened with quality headphones) I could easily hear lots of audible noises, and even the basic rhythm and some melody of the original song ! Therefore, my MacBook Pro system, although claiming to by capable of 24-bit 96kHz (and setup correctly for it) 'has a nonlinearity causing audible intermodulation of the ultrasonics' !

I also heard lots, easily, on these ultrasonic warble files:

26kHz - 48kHz warbling tones (24 bit / 96kHz) [10 second WAV]
26kHz - 96kHz warbling tones (24 bit / 192kHz) [10 second WAV]

Monty also includes some test files that prove that 16-bit can represent arbitrary sounds quieter than the oft quoted -96dB (which is merely an RMS value, not a limit):

'I have linked to two 16 bit audio files here; one contains a 1kHz tone at 0 dB (where 0dB is the loudest possible tone) and the other a 1kHz tone at -105dB.

Sample 1: 1kHz tone at 0 dB (16 bit / 48kHz WAV)

Sample 2: 1kHz tone at -105 dB (16 bit / 48kHz WAV)

Above: Spectral analysis of a -105dB tone encoded as 16 bit / 48kHz PCM. 16 bit PCM is clearly deeper than 96dB, else a -105dB tone could not be represented, nor would it be audible. How is it possible to encode this signal, encode it with no distortion, and encode it well above the noise floor, when its peak amplitude is one third of a bit? Part of this puzzle is solved by proper dither, which renders quantization noise independent of the input signal. ..'

I performed some spectrum analysis in Audacity on some of these Monty test files, visit: Audacity: miscellaneous tips.

On the 16-bit "sound capture below 96kB" proof:

On the 30kHz-33kHz ultrasonic 24-bit 96kHz file:

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