Emagic Logic Audio 2.5

Most of the major music software manufacturers now recognise the PC as a serious music platform and are ensuring that the PC versions of their sequencing software don't miss out on any important features. Paul White gives an overview of the latest Logic Audio for Windows '95 and compares it with the Mac version.

It's less than a year since I checked out the Apple Mac version of Emagic's popular sequencing program, Logic Audio 2.5 (see SOS February '96), so I had some idea of what to expect from the PC equivalent now available. Even so, there are differences between the two versions, and it's those that I'd like to concentrate on, rather than going over the more well‑known MIDI features of the program. Some Mac/PC disparities are understandable, given the differences between the PC and Mac computing engines, though there are other features which seem to have been omitted or changed on the PC version for no obvious reason.

Logic Audio 2.5 combines MIDI sequencing with score editing and printing, plus up to eight tracks of direct‑to‑disk multitrack recording, though the number of tracks you can run at one time will depend on the speed and type of PC you have, and on the audio card/interface you choose. For reliable 8‑track recording, you should use a Pentium 90 or faster, with at least 16Mb of RAM, and you'll need plenty of disk space, as audio takes up around 5Mb per minute for each track recorded. Emagic claim that the system will run on faster 486 machines at a pinch, but the number of audio tracks will be reduced, and you should only do this if you're desperate.

Hard drives should have an average access time of 18ms or less, and a sustainable data transfer rate of 800K/sec. For reliable operation with more than four tracks, a drive with a mean access time of 10ms or better is recommended, as is a data transfer rate rather greater than 1Mb/sec.

One benefit of using Logic Audio 2.5 for the PC, other than the relatively low cost of this computer platform, is the choice of affordable audio/sound cards with which the program can be run. At the time of writing, the Turtle Beach Tahiti card is apparently suitable for use with 2.5, and DAL's Card D is also said to be fine, though you can also get limited results with a SoundBlaster card, if you're prepared to work around its shortcomings. Those seeking higher quality can use a Digidesign Audiomedia III card, with either the Wavedriver that comes with the card, or Digidesign's DAE driver, which comes packaged with Logic Audio. I was told that running under DAE may be unreliable, possibly because of bugs in DAE itself, but as I'll explain later, DAE actually seemed to work well for me. Wavedriver, on the other hand, produced horrendous timing problems that I could find no way to resolve. In terms of other hardware suitability, the Logic Audio manual suggests that compatibility with the Yamaha CBX series of external boxes will be forthcoming, but as yet it is not supported.

For the review, I used a Pentium 90/16 fitted with a 1Gb hard drive and running Windows 95; though the Logic 2.5 sequencer (without audio) will also run under Windows 3.0 or 3.1, Logic Audio 2.5 requires Windows 95. On the soundcard front, I had a Creative Labs AWE32 (to provide the MIDI interface) and an Audiomedia III card fitted. Though it is possible, in theory, to use an AWE32 card for audio, its restricted duplex abilities, when it comes to simultaneous record and playback, mean that you need a special software driver if you want to record and play at the same time. Apparently, beta versions of drivers are available on the Internet, but these only allow you to record in 8‑bit mode if you need to monitor previously‑recorded audio tracks. You could, I suppose, turn off the audio track playback and record your new audio in 16‑bit mode while monitoring only the MIDI tracks, but this would be rather restrictive. I'm told that there may be newer drivers in the pipeline that attempt to provide simultaneous 16‑bit playback and recording. Unfortunately, Logic Audio can't run with Digidesign's Session 8 hardware, so at the moment, there's no multi‑output hardware option available, leaving PC users in roughly the same position as Power Mac users running with the Mac's built‑in AV audio interface.

Overview

For those who haven't seen Logic before, its main arrange page owes a lot to Steinberg's Cubase — but then much the same can be said of most long‑standing MIDI sequencing software. The main differences are Logic's ability to loop sequences, and its Environment page, which stores details of your instruments, their patch names, and their MIDI connections. Though you can do a lot of clever things in the Environment, by using virtual cables and creating MIDI faders, virtual delay lines, arpeggiators, and so on, its most practical benefit is that when you want to pick a sound for a track, you're able to choose from a list of instruments, and then from those instruments' patch names, not from a list of MIDI port numbers, MIDI channels and patch numbers.

Logic Audio PC allows you to address internal synth soundcards as virtual MIDI ports, but the way in which this is achieved isn't as intuitive as I feel it could have been. I expected the driver to come up as a virtual port in the ports column of an instrument's MIDI address, but this didn't seem to happen, so I had to use a bit of virtual wire to connect my virtual instrument to the virtual port, on the Environment page.

Logic/Logic Audio employs a multi‑window approach; not only can you have lots of different windows open at once, you can also have several copies of the same window open, but set to different zoom resolutions or looking at different parts of the song. Windows can be linked so that changes in one are reflected in the others, and a Catch mode button makes it easy for the window display to jump to whatever part of the song is currently playing.

The main edit windows show the recorded part as a musical score, as a 'piano roll' matrix, or as a MIDI event list, and there are further windows, including Hyper Edit and Hyper Draw, for editing controller information. Both MIDI and audio mixes may be automated for level and pan — plus controller information, in the case of MIDI — and full sync is provided via MTC or MIDI clock, with comprehensive (and largely automatic) tempo‑mapping facilities. Tempo changes can be entered numerically or graphically, and a random tempo function can be used to humanise compositions that have had the life quantised out of them! Logic has a particularly powerful set of intelligent quantise options, and the more adventurous can visit the Transform page, which is very roughly equivalent to Cubase's Logical Edit.

Because multiple open windows can get very untidy, it is possible to create Screensets of your commonly‑used screen configurations, selectable via the computer's numeric keys. Even so, the screen soon gets busy, so if you can stand working with smaller windows, it's worth changing your screen resolution so you can cram more on. A 17‑inch monitor (or larger) is highly recommended.

Logic Audio makes extensive use of colour, allowing you to create some kind of visual order out of the sequences in the arrange page; as with older versions, you can also create 'folders' of numbers of tracks, to help simplify editing and to make the screen clearer. At one extreme, you can ignore folders altogether, while at the other, you can stuff an entire song into a folder if you like. In practice, it can help to create folders for verses, choruses, intros, links and so on, which makes it very easy to drag them around to try out different arrangements.

Installing

Installing Logic Audio 2.5 is very straightforward. Once you've started the installer program, you're prompted to change disks when necessary, and that's all there is to it. A hardware key is used to copy‑protect the program, and this plugs into one of the 'com' ports on the back of the PC. A short adaptor cable is provided, enabling either the 9‑pin or 25‑pin port to be used.

A number of MIDI interfaces are supported, from the AWE32's single MIDI port to multi‑port external boxes such as MOTU's MIDI Time Piece. Some interfaces have separate ports for SMPTE sync'ing the computer to a tape machine, though if you have a system that will work with MTC (MIDI Time Code), you don't really need to worry about a separate SMPTE port. There are many interfaces that will do the job, but I'd recommend you check with Emagic's tech support before buying one, if you don't have one already, just to make sure there are no compatibility problems.

There are performance limitations when using internal cards with analogue I/Os, because the analogue audio circuitry is inside the computer's case, and some crosstalk between the analogue and digital circuitry inside the computer is inevitable. Typically, a good internal card might manage an 85dB signal‑to‑noise ratio, while an external converter (for example, feeding the digital input of an Audiomedia III card from a DAT machine or external converter box), could push that figure much closer to the theoretical maximum of 96dB for a 16‑bit linear system.

Test Drive

For newcomers to Logic, the best way to get started is to load the demo songs which come as part of the support software, along with a number of useful mixer maps, GM (General MIDI) instrument Environment objects, and so on. Though unlikely to ever make the charts, the demo songs do include both MIDI and audio data, which you can play around with before recording your own. Perhaps the best way to regard the audio part of an audio sequencer is as a sampler capable of playing back one long sample at a time on each track. Once you record a piece of audio, you can't go changing the tempo of the song, because the audio tempo won't change along with the tempo of the MIDI tracks. There are tools within the Digital Factory part of the program that enable audio to be stretched in time or pitch if you have to make a piece of imported audio fit, but it's far easier to get the MIDI tempo correct before you start recording audio.

Before using Logic Audio 2.5 for the first time, it may be necessary to calibrate the Playback Driver to compensate for the different timing characteristics of different audio cards. A simple procedure is described in the manual, which involves recording a MIDI click‑track onto an audio track, then adjusting the driver settings until there is no delay between the recorded click and the original MIDI click. You also need to set an audio path, so that Logic Audio knows in which folder and on which hard drive to store your recordings.

This part of the procedure initially caused problems for me, as I opted to work with the Wavedriver rather than DAE, and found that the timing between the audio and the MIDI click was not only around one eighth of a bar out of sync, it also wandered. No amount of adjusting the delay offset in the Audio Extensions box would fix this. DAE also started badly, until I tried pressing the Recalibrate Inputs button in the Hardware Setup box, accessed from the Audio window Options menu. Once this is done, the program comes up with a 'whinge' box when you start recording, to inform you that some audio/MIDI sync problem has occurred. Dismiss this, by clicking on Continue, and all seems to be well. I managed to record eight test tracks of quantised drums, and they all played back tightly, exhibiting that reassuring flanging sound that indicates the timing is acceptably precise.

In common with other PC programs, Logic Audio 2.5 uses the .WAV file format, though stereo .WAV files are automatically converted to two mono files when imported, which means that you need twice as much disk space as required for the original file. Once the files are opened in Logic Audio, the program recognises that the files are halves of a stereo pair and ensures that they are treated identically, even though they're assigned to two tracks rather than one. To record a stereo file, all you need do is set an odd‑numbered Audio Input object to 'Stereo' and the input to the right of it is linked.

Most editing is non‑destructive. If you trim down a recording to play only a short segment of what was recorded, the rest of the material is still there — the selected region is like a small window onto a bigger picture. There's also a Strip Silence feature, which acts almost like a noise gate to separate a piece of audio into regions based on signal level. For example, you could feed in a drum recording, then juggle the threshold so that the individual beats were separated into individual regions. This operation is non‑destructive, and is great for creating new or modified rhythm parts.

Destructive editing operations are those that actually alter the data in the soundfile in some way. A number of such functions are available, including the ability to normalise, change gain, erase, fade‑in/out, or even reverse sections.

Audio regions appear in the Arrange window alongside MIDI sequences, and, with some exceptions, can be treated in similar ways, as regards cutting, moving and copying. As on the Mac version of Logic Audio, audio regions can be looped to provide continuous playback.

A much appreciated 2.5 feature is the ability to force MIDI tempo to automatically adapt to the length of an audio sequence, so that both MIDI and audio bars are precisely the same length. This can save a vast amount of trial and error when you've started with a chunk of audio and you're trying to make the song tempo fit.

Audio tracks may be automated by recording the virtual control movements in real time, and Audiomedia III users have access to EQ, but only if running under DAE. While switching between DAE and Wavedriver, I noticed a couple of quirks that other users may have experienced. Aside from the fact that I couldn't get Wavedriver to sync on my particular system, I was also unable to monitor any input levels at all unless I went into record. (With DAE, you monitor the input as soon as the Audio Input object is switched to Record Ready mode.) What's more, inputs 1 and 2 seemed to be interchanged whenever I switched between Wavedriver and DAE. These oddities are probably associated with the card and its drivers rather than with Logic Audio, but I felt it worth mentioning in case anyone else has come across the same situation. Something that almost certainly is Logic Audio's problem, however, is that when setting up the parameters for the Audio Inputs, you'll often find that the items you want are greyed out, which normally implies that you can't select them. However, they work perfectly well if you just go ahead and select them anyway, so there's obviously some little display management bug hiding somewhere in there.

Hyper Draw, a graphical automation feature originally introduced in Logic, may be used to automate tracks by creating envelopes, rather like the ones used in Pro Tools or Digidesign's Session, where the user inputs level or pan data at any desired point by clicking with the mouse, and the computer 'joins the dots', using straight lines. The main difference between how this is done for audio and MIDI data is that with audio tracks, the controller data is recorded on a 'control' track adjacent to the audio, not directly into the audio sequence box itself.

Fun Factory

The Digital Factory is where Logic Audio keeps its bag of audio processing tricks, many of which are destructive — in the nicest possible sense of the word.

The Digital Factory is actually a suite of sub‑programs comprising the Time Machine, Groove Machine, Audio Energiser, Sample Rate Converter, Silencer, Audio to MIDI Groove Template, Audio to Score, and the Quantize Engine. Audio to Score and Audio to Groove are non‑destructive, as they effectively 'read' the audio file and then produce MIDI information from it, but all the other processes create new audio data files. Though the treatments are undertaken off‑line, the majority of the Factory processes can run in the background. Considering the complexity of some of these Digital Factory processes, they actually work very quickly.

• The Time Machine makes it possible to change the pitch and/or length of an audio file, so you can pitch‑shift without changing tempo, tempo‑shift without changing pitch, or apply a little of both. All such algorithms have side effects, and the Time Machine is no exception, but you have far greater range and flexibility than you'd expect from the pitch‑shifter in an effects box, and the side‑effects are far less noticeable. With care, modest amounts of shift can be applied with virtually no audible side‑effects, and even drastically‑altered sounds often remain usable. The shift range is +100%/‑40%; dropping a drum track by 30% resulted in a surprisingly natural sound.
• The Quantize Engine is the sort of thing we'd have written April Fool pieces about five years ago. It's a process for quantising an audio recording, which uses time‑shifting algorithms to move events around within an audio region. If you don't expect the impossible, it really works well, not just on percussion, but also on musical material. Just how artifact‑free the result is depends on the amount of movement required to get the music in time, and on the nature of the material being processed. Different algorithms can be selected to optimise the process for various types of material. The Groove Machine is very similar, but it allows you to add a degree of swing or groove to the audio, rather than using rigid quantisation. A neat graphical interface lets you define the groove points before processing.
• The Audio Energiser dramatically increases the average signal level of a chunk of audio by applying a clever peak‑limiting algorithm and normalising the signal at the same time. It's not always ideal on mixes, but is great on rock guitar and useful on vocals.
• The Silencer combines single‑ended noise reduction with digital spike removal. In most cases, these processes will be used to minimise tape hiss or other forms of background noise, as well as to reduce the effect of pops or glitches — a problem encountered on occasion by most people using digital recorders. The spike reduction process can be used in a couple of different ways. In Rebuild mode, spikes are identified, then removed, leaving a gap to be filled by electronic guesswork. In Filtering mode, the spikes are left intact, but momentary filtering is applied to reduce their audibility. Emagic don't claim that the Silencer is a professional de‑clicker, but even so, it copes well in identifying and disguising the type of digital spikes that occasionally afflict DAT tapes.
• The Sample Rate Converter does just as it says on the packet — if you have a fixed 48kHz DAT machine, you can convert a file to 44.1kHz, for example. The dialogue box allows any source and destination sample rates to be set up, so it's very flexible.
• Audio to MIDI Groove Template works by reading the groove from a rhythmic piece of audio, then creating a groove template which allows you to give your MIDI sequences the same feel. There are various parameters to adjust, so that you capture only the beats you intend to, and if the source rhythm doesn't have beats at every required quantise point, you can insert your own points manually.
• Audio to Score Streamer is designed to read timing and pitch information from a monophonic audio file, so that either a score or MIDI data can be extracted, which mimics the same musical information. MIDI files created in this way will include any pitch‑bend data needed to follow bends, as well as note and velocity information, but polyphonic signals merely confuse the system, resulting in an output of garbage. Various parameters are available to help optimise the process for different voice and instrument characteristics.

Mac VS PC

Logic Audio on the Mac is well established, but the PC version has a limited history. From what I've seen, Emagic have come up with a very thorough translation of the original program, with only a few cosmetic and feature changes differentiating the Mac and PC versions. The whole display looks slightly chunkier on the PC, possibly because of the font used, and one or two icons, such as the zoom buttons, are in slightly different places, but on the whole, you can move from one platform to the other without too much difficulty.

On the Mac version, you can set up your own choice of which edit window opens when you double‑click on a sequence, and I usually opt for the Matrix (piano roll) editor. However, this option is absent from the PC version, though you can use the Screensets function to save a screen setup with an open Matrix edit window, if you need to get to it with a single button press. Alternatively, you can double‑click on any note in the Score window, or take the long route and open the Matrix window from a menu.

Once you're in the Matrix window, another change is evident: on the Mac version, all the little bars representing notes are coloured according to velocity, with blues and greens being quiet and reds being loud. On the PC version, however, the bars are grey, just like older versions of Logic for the Mac. 'Touch Tracks' has also gone in the PC version. On the Mac version, sequences or folders could be assigned to keys on the keyboard, allowing arrangements to be improvised in real time, based on ready‑recorded sections. Apparently this omission isn't due to any musical prejudice, but rather to the way the PC operating system works. Emagic are hoping to find a workaround that will allow them to include this feature in later versions.

When using the audio side of the program, I found no real problems other than the ones mentioned earlier in this review. Though the PC version is supposed to be fast, I found that the audio recording and playback mode took a second or two to start or stop, something I hadn't noticed so much on my old Mac Quadra. A read‑me file that covers known problems with specific soundcards is included with the program.

On my Pentium 90, Logic Audio runs very quickly indeed, though there are little niggles associated with how the PC does business, and rather larger ones with how some soundcards and drivers behave. What's more, in the Matrix Edit page, whenever you drag a note by its corner to lengthen it, the PC insists on trying to redraw the screen, at around 10 redraws per second, for as long as you're editing the note. The result is rather like a strobe‑induced migraine. On the whole, though, the PC version is pretty smooth, the screen redraws are fast, and I didn't make it crash even once.

Summary

Though Logic Audio is a complex program, its pertinent points can be learned very quickly, and the supplied manual is pretty thorough and well indexed. A large monitor makes life a lot easier, though one thing the PC guys do miss out on is the Mac's ability to have two monitors configured as one large, virtual screen. The Screensets feature is invaluable, and as with the Mac version, individual Screensets can be locked so that you don't change them inadvertently. You can configure almost any key commands to a combination of keys of your choice, and there's also the option to control key transport and record functions directly from a MIDI keyboard.

The Digital Factory is by no means unique — most serious Audio + MIDI packages include a digital processing section — but what's on offer is very well implemented and covers the kind of processes that normal people are actually likely to use. The pitch‑shifting algorithms are particularly good, while audio quantise is great fun for mangling samples or pieces of live playing. The Audio Energizer and Silencer facilities are also very effective in reducing the level of clicks and hiss in a recording.

Considering that not every piece of software translates to the PC as painlessly as we might wish, Emagic have done an excellent job, though the Mac version will continue to lead until somebody comes out with a suitable multi‑channel audio interface for the PC that Logic Audio can run with.