Apple Pro Training Series: Logic Pro 7 and Logic Express 7
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| Before you record audio into Logic, we need to address some basic functions and features. Think of Logic as being like a high-end professional camera. It offers a lot more features and flexibility than that cheap throwaway. You have many more options that give you control over the final image. Before you snap the picture, however, you need to make sure that all the settings are just right so that they'll create the best possible image. In Logic, some options are set just once, before you start to record, while others may need changing during the process of creating your song. You'll choose some settings based purely on personal preference. Nevertheless, it's best to think through all your choices before beginning your work. Choosing a Sampling Rate
We first addressed sampling rate in Lesson 4, "Editing Audio Regions," when you used the Sample Editor to convert the HH.aif file from 48 kHz to 44.1 kHz to match the sampling rate of the song. It is extremely important that you are aware of your song's sampling rate setting, because it greatly affects your computer's performance. Logic can support sampling rates of up to 192,000 samples per second, but a rate that high takes well over four times the disk space and four times the digital signal processing power as the 44,100 samples per second used for this song. You must also make sure that the sampling rate you've selected in Logic is compatible with the audio interface you are using. Most audio interfaces support 44,100 samples per second (44.1 kHz), so you should be fine using the 44,100 setting when recording audio in this lesson.
Setting the Bit Resolution
Logic can record using 16- or 24-bit resolution. The higher the bit resolution, the more accurately Logic can represent the audio waveform. Using 24- instead of 16-bit resolution will require more processing power from your computer's CPU and take slightly more disk space when you start to record audio. However, with the current generation of technology, 24-bit recording has become quite standard.
Setting the I/O Buffer Size
Logic's buffer setting controls how big a bite the computer tries to chew at one time when working with audio. This setting, which is measured in samples, can dramatically change the way in which your system performs, especially when recording. Typically, the bigger the buffer size, the more recorded channels of audio can be played at the same time, and this reduces the processing power required by your computer's CPU. However, bigger buffers make the system react more slowly when recording. For example, with a large buffer setting you may notice an audible delay between playing a note on your MIDI controller and hearing one of Logic's Audio Instruments react to that note. This delay is called latency, and it can also seriously affect your audio recordings. For example, you may sing a note into a microphone and then experience a delay before hearing it through the speakers. Should this happen, you'll need to use a smaller buffer setting. But it's a trade-off, because a smaller buffer setting forces your computer's CPU to work harder, which means that fewer total audio tracks, plug-ins, and Audio Instruments can play simultaneously. With these considerations in mind, start with a buffer setting of 64. If you later find you need more tracks, plug-ins, or Audio Instruments, you can increase the buffer size.
Enabling Software Monitoring
When you're recording an audio track, software monitoring allows you to hear the signal in your speakers after it has passed through all the Audio Input, Track, and Output Objects you have created in Logic's environment. This enables you to hear how settings such as level, panning, and plug-ins affect the audio as you are recording it. The potential drawback is that since you are recording the audio live, the computer can't look ahead at what's coming. If you have a slower computer or are using large buffer settings, you may notice a delay between when the audio is created and when you hear it.
Selecting a File Type
When Logic records audio, the audio is stored as PCM (pulse-code modulated) audio files on your computer's hard drive. These are simply uncompressed audio files, and Logic can create your choice of WAV, AIFF, or SDII PCM audio. AIFF files are the most common type of uncompressed audio files on the Macintosh, so let's choose AIFF as the file type for recording.
Specifying a Record Path and Name
Unlike MIDI data, which is stored directly within the Logic song file, audio files are stored separately on your computer's hard drive. Audio files can be kept anywhere on your hard drive, though typically you should record to an Audio Files folder located in the same directory as your Logic project file. This type of file management makes it easy to find the files recorded for your song, and it also simplifies the process of backing up songs once you're done, because all the audio files are right there beside the project file. However, Logic provides you with full control over where audio files are recorded by allowing you to set your audio record path. Each audio file you record needs a unique filename. Instead of manually naming each one, you can have Logic automatically use the name of the track as the filename. Logic will automatically add numbered extensions to the filename to prevent duplicates when you record on the same track multiple times. Let's specify an appropriate record path and file-naming convention for your audio files.
Selecting Auto Input Monitoring (Logic Pro Only)
An audio track either can output the Audio Regions it finds as the SPL moves across them, or it can output the signal it receives from its input. Typically you want to hear the Audio Regions during playback and hear the input in the following two situations: when the track is record-enabled but the Transport is still (so you can set levels), and when the Transport is moving and in Record mode (which is the actual act of recording). Enabling Auto Input Monitoring automatically switches between the signals that are to be monitored, depending on the conditions just described. Since this automatic switching is very helpful, let's go ahead and select Auto Input Monitoring.
Enabling the Replace Mode
In most cases when you are recording, you'll want to use something called the Replace mode. This simply means that when Logic is recording onto a track, any information on that part of the track is overwritten with a new Object. In other words, Logic behaves like a regular audiocassette recorder. However, Logic does not rewrite or delete the previously recorded audio on the hard driveit's still part of the audio file and you can get it back at any time. This gives a huge advantage over the cassette recorder: You can always undo your recording and go back to where you were before! NOTE Recording without the Replace mode can get very confusing. Without Replace engaged, Logic will present multiple recorded Objects on the same track. In an audio track, only one of these Objects can be heard at a time. But in a MIDI track, multiple Objects can be heard from the same track. Sometimes the Objects overlap to the point where you may be hearing things that you can't see in the Arrange window.
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