Apple Compressor 3 - Manual (Page 224)

• Bit Rate pop-up menu: Choose from one of the following bit rate settings. Whatever
setting you choose, quality will vary from frame to frame to maintain the selected bit
rate.
• Constant at: Sets a manually specified bit rate based on your slider setting.
• Low VBR: Sets an overall low quality for all frames.
• Medium VBR: Sets an overall medium quality for all frames.
• High VBR: Sets an overall high quality for all frames.
• Bit Rate slider and field: (Available only with the “Constant at” setting.) Move the slider
to set the overall video bit rate for your output media file between the range of 32 kbps
and 2048 kbps, or enter a specific number in the accompanying field.
Audio Pane
You use the Audio pane to set the audio track quality, sample rate, quality, and bit rate
of the MPEG-4 output file.
Sample Rate pop-up
menu
Bit Rate slider
Use the following buttons and slider to make more detailed adjustments.
• Audio Enabled checkbox: Make sure that this checkbox is selected if you want the MPEG-4
Part 2 output format audio settings to be applied.
• Channels buttons: Choose the audio channel for your output media file to be either
mono or stereo.
• Mono: Choose this button for mono output.
• Stereo: Choose this button for stereo output.
• Sample Rate pop-up menu: Choose from one of the following sample rates: 8, 11.025,
12, 16, 22.05, 24, 32, 44.1, or 48 kHz. You can also choose Recommended to have
Compressor choose a sample rate that is suitable for the Channels and Bit Rate settings.
Note: If you choose Recommended, the sample rate is not determined until the
transcode actually starts.
224 Chapter 19 Creating MPEG-4 Output Files