Apple Compressor 3 - Manual (Page 179)

Some example settings and uses include:
• 32 kbps: AM radio quality, suitable for medium quality speech
• 96 kbps: FM radio quality, suitable for high quality speech or medium quality music
• 128 kbps: Suitable for good-quality music
• 256 kbps and 320 kbps: Suitable for music that is near CD quality
• Use Variable Bit Rate Encoding (VBR): This setting varies the number of bits used to store
the music depending on the complexity of the music. This can help keep file size to a
minimum.
• Sample Rate pop-up menu: The number of times per second that the music waveforms
are captured digitally. The higher the sample rate, the higher the quality and the larger
the file size. Don’t choose a sample rate higher than the rate used originally to store
the music or you’ll waste space. CD quality, for example, is 44.100 kHz, so choosing a
higher rate when you’re encoding from a CD is unnecessary.
• Channels pop-up menu: If you don’t have stereo speakers or if your audio files are
monaural, choose Mono (mono files are about half the size of stereo files). If you’ll be
listening to your MP3 files using your stereo system, choose Stereo.
• Joint Stereo: When this checkbox is deselected, your MP3 files contain one track for the
right stereo channel and one track for the left. In many cases, the two channels contain
related information. When the Joint Stereo checkbox is selected, one channel carries
the information that’s identical on both channels, and the other channel carries the
unique information. At bit rates of 160 Kbps and below, this can improve the sound
quality of your converted audio.
• Smart Encoding Adjustments: Select this to have Compressor analyze your encoding
settings and music source, and then adjust settings to maximize quality.
• Filter Frequencies Below 10 Hz: Filtering inaudible frequencies results in smaller, more
efficient files without perceptible loss of quality.
MP3 Transcoding Workflow
How you use Compressor to transcode your audio into MP3 format files depends on how
you intend them to be used. The basic steps are described below.
Stage 1: Creating a Batch
As with any transcode, you need to start by creating a batch. See Preparing Compressor
for Transcoding with Custom Settings for more information.
Stage 2: Creating Jobs with the Source Audio Files
Import the source audio files either by dragging them from Finder to the batch or by
choosing Job > New Job With File.
179 Chapter 16 Creating MP3 Output Files