We explore Logic Pro’s bounce and export options.
Though it may seem that things were simpler in the ‘analogue days’, delivering content for release on vinyl or cassette was fraught with problems. Variables such as differing tape noise‑reduction systems, badly maintained or misaligned master tape machines and equalisation choices in the cutting room could mean disappointment when you finally got to spin your latest opus. It got easier for a while in the early days of digital as all you needed to do was supply a 44.1kHz, 24‑bit file (or CD‑R) to your manufacturing plant and you’d be reasonably sure it would sound the same on CD playback. But with the explosion in the delivery ecosystems for music, you need to be sure that any files that you send to a streaming site, duplication plant or mastering engineer are of the correct format.
Most of the time, you’ll be bouncing out (or rendering) stereo files, and the format for these depends on where your music will end up. Logic’s Bounce and Export features are accessed from the File menu. If you open the Bounce window (shown above), you’ll see that several options are available. You can bounce the whole project or just a selection, in which case you need to make sure the start and end parameters are correctly set — these values are also the same as those for a Cycle region. If you have no external hardware patched in, choose Offline bounce, otherwise you’ll need to wait while the whole track plays as it renders to stereo in real time. The Include Audio Tail option is there to make sure any reverb or echo at the end of the bounce is captured, but sometimes this can extend the song length — so it’s better to make sure that the last bar in the bounce is beyond any residual processing. You can load the bounce back into Logic for further editing if you wish.
The 2nd Cycle Pass option performs a ‘practice’ bounce once before looping back to complete the actual rendering. This can be useful when you want to have any effects from the end of your project, such as a reverb, incorporated into the start of the actual bounce — such as when making loops. The settings for the bounce will depend on the ultimate destination of your rendered audio.
The only rule here is that the output level on the master Track should not go beyond 0dB. While the internal processing in Logic means that it’s unlikely you’ll clip any individual channel, some plug‑ins that emulate vintage processors expect to see a level that is closer to that which the real hardware would accept. It’s perfectly possible to reduce the stereo master fader to avoid your bounce clipping, but it is much better practice to avoid this by properly setting the gain of individual channels. What loudness level your bounce should be depends on the destination of your audio and, perhaps, the ‘market’ at which you are aiming your music. Logic has a few metering tools that will help you set the correct levels, so insert a Level Meter and Loudness Meter (both are found in the Metering menu) as the last plug‑ins on your Stereo master channel.
Probably the most useful setting on the Level Meter is True Peak & RMS, as this will alert you to any unexpected transients as well as give you an idea of the general loudness of the track. It’s instructive to play your reference tracks through your Level Meter too — you’ll find that while peaks are often hitting close to 0dBFS, the RMS usually sits at or below ‑12dBFS.
The Loudness Meter displays the Loudness Units Full Scale (LUFS) of your file — the smaller the value, the greater the apparent loudness. It’s useful to know the LUFS of your bounce as some online platforms specify a maximum value. Setting the correct level for a bounce is usually part of the mastering process though, so if you’re bouncing out to send off to someone with magical ears (and a treated studio), you’ll want your master track’s metering bouncing around at the ‑12 to ‑18 dB level to give the mastering process some headroom.
If you’re bouncing your project as a file destined for CD manufacture, you’ll choose PCM, AIFF (or WAV), 16‑bit interleaved with dithering. This latter process is seen as a bit of a black art but dithering introduces noise into the bounce to ‘cover up’ the effects of the reduction in bit depth. Some people can spot the quality of the different dither types, so if you are one of these, you can experiment with the different dither types available. For the rest of us, the UV22HR option should be fine.
The digital music age has brought about an explosion of different distribution outlets, all requiring different types of content.
Once bounced, the CD manufacturing process shouldn’t adulterate the audio further. For all other platforms, you’ll need to take their advice as to what format and loudness of audio they expect. For example, Spotify recommend the ITU 1770 (International Telecommunication Union) standard of ‑14dB LUFS. Most platforms will adjust your audio automatically to the levels they require, so if you don’t want them to meddle with your carefully created tracks, it’s essential that you give them exactly what they require. But as a rule of thumb, for mastering, export your audio at the sample rate you recorded it at, with 24‑bit depth and plenty of headroom, while for streaming, export your audio at 24‑bit and at a LUFS level requested by the platform.
Logic’s Adaptive Limiter, placed just before your meters, can help increase the average apparent loudness of your bounce, so it’s worth experimenting with this — but be aware that too much gain reduction applied here can have deleterious effects on the audio, and a proper mastering process is a better option. You can also use this plug‑in to set the output ceiling to make sure your audio never clips the output — but again, this is no cure for proper gain staging elsewhere in your project.
You can, of course, also bounce MP3 and AAC files directly from Logic if you want a quick and dirty way to audition your mix or, if you’re feeling brave and have a suitable burner, create a CD‑R from your project. If you’ve recorded at high sample rates, you might need to downsample your audio for distribution — I usually do this as a separate process with my bounced files. The quality of the various methods of sample rate conversion is quite a hot topic and, while it’s true that not all processing is equal, I have found that loading higher sample rate audio into a Logic project set to 44.1 or 48 kHz produces very acceptable results when bounced out.
Increasingly, engineers are requesting stems rather than complete mixes. Those working in the film and TV world have been supplying these for a while now and I’ve produced many stems this year for my online collaborations. Fundamentally, stems are just submixes of tracks. For example you might create stems of vocals, basses, drums, guitars and keyboards. The creation of stems makes any post‑mixing balancing, and the creation of vocal‑free mixes for advertisements and so on, much easier. As I write, Logic unfortunately doesn’t (yet) have a ‘stem bounce’ feature, and creating them can take a little planning and thought, depending on the way you work. We covered the creation of Stems for those working in the box and in a ‘hybrid’ fashion when using external hardware, in the May 2021 issue: www.soundonsound.com/techniques/exporting-logic-projects-other-daws
Many people use Logic to produce beats and loops. These can be created from a set of Regions, or by using the Live Loops window (covered in the October 2020 issue: www.soundonsound.com/techniques/live-loops-logic. The Export Region/Cell window has various options to make sure you have all the metadata required when using these loops in other projects.
Here you can determine if the beat loops and/or conforms to the project tempo or not. Choose the Instrument Descriptors carefully, as these will be searchable from the Loop Browser. You can set the Musical Scale and Key, if required, and a tempo for the beat or loop. Once created, these are accessible from Logic’s Loop Browser and can, of course, be exported as audio files by dragging them to the Arrange page, Ctrl‑clicking on the Region created and selecting Export As Audio file.
When I’m working remotely with others, I normally send them stems or audio files even if they are using Logic, as you can never guarantee that the other person will have access to all your instruments or plug‑ins. If they are using Logic, I usually use the strangely named ‘Replace All Tracks’, to ‘burn’ the plug‑ins and instruments as audio files. This is also a quick and easy way to make sure that when you return to a project in the future, you can still access any plug‑ins that have been rendered obsolete by the march of technology.
You can choose to bypass all plug‑ins in your render, and whether to include automation in the bounce. If my collaborator is not a Logic user, I’ll also include an exported MIDI file. Not only will this contain any musical notation for the instrument parts, but also any tempo and time‑signature changes in the project (I make that kind of music!). My colleague can then be sure that everything lines up when adding further recordings.
Andrew S Tanenbaum once wrote, “The good thing about standards is that there are so many to choose from,” and the digital music age has brought about an explosion of different distribution outlets, all requiring different types of content. It’s always worth making sure what format is required by each platform but, with a little thought, Logic should be able to generate all of the files required.