3
Table Of Contents
- Compressor 3 User Manual
- Contents
- Welcome to Compressor
- Getting Started Quickly
- Ways to Use Compressor
- The Basic Transcoding Workflow
- The Compressor Interface
- Setting Compressor Preferences
- Importing Source Media Files
- Creating, Previewing, and Modifying Settings
- Finalizing Jobs and Submitting Batches
- Creating AIFF Files
- Creating Dolby Digital Professional Output Files
- About the Dolby Digital Professional Encoder Pane
- General Information About Creating Dolby Digital Professional Files
- Converting Stereo Audio Files to Dolby Digital Professional Format
- Assigning Files to Surround Sound Channels (Manual Method)
- Assigning Files to Surround Sound Channels (Automatic Methods)
- Assigning Files to Surround Sound Channels with Droplets
- Options for Spatial Mixing
- Creating DV Stream Output Files
- Creating H.264 for Apple Devices Output Files
- Creating H.264 for DVD Studio Pro Output Files
- Creating H.264 for Blu-ray Disc
- Creating Image Sequence Files
- Creating MP3 Output Files
- Creating MPEG-1 Output Files
- Common Uses for MPEG-1
- MPEG-1 Specifications
- About the MPEG-1 Encoder Pane
- About the MPEG-1 Video Tab
- About the MPEG-1 Audio Tab
- About System and Elementary Streams
- MPEG-1 Transcoding Workflow
- Configuring the MPEG-1 File Format for Web Use
- Configuring the MPEG-1 File Format for DVD Use
- Creating the MPEG-1 Video for DVD Setting
- Creating the MPEG-1 Audio for DVD Setting
- Optional—Creating an MPEG-1 for DVD Group and Destination
- Creating MPEG-2 Output Files
- Creating MPEG-4 Output Files
- About MPEG-4 Part 2
- About the MPEG-4 Part 2 Encoder Pane
- Using Default MPEG-4 Part 2 Settings
- Customizing MPEG-4 Part 2 Settings
- Audio Podcasting Workflow
- Stage 1: Configuring the MPEG-4 Output for Audio-Only Output
- Stage 2: Including Podcasting Information
- Stage 3: Applying the Setting to a Source Media File’s Target
- Stage 4: Entering Annotations for the Output Media File
- Stage 5: Creating and Configuring Markers for the Output Media File
- Stage 6: Submitting the Job and Verifying the Output Media File
- Adding Additional Settings and Presets
- Creating QuickTime Movie Output Files
- Creating QuickTime Export Component Files
- Adding Filters to a Setting
- Working with Frame Controls
- Adding Geometry Settings
- Adding Actions
- Using the Preview Window
- Creating and Changing Destinations
- Using Droplets
- Appendix A: Keyboard Shortcuts
- Appendix B: Solving Problems
- Resources for Solving Problems
- Solutions to Common Problems
- Exporting from Final Cut Pro and Distributed Processing
- QuickTime Reference Movies
- Cluster Settings for Extended Transcoding Sessions
- Cleaning Up Cluster Storage
- Using Apple Qmaster with an NFS Server
- Apple Qmaster Distributed Processing and Xsan
- Compressor Command-Line Usage Requires Login
- Create Blu-ray Disc Job Action
- Contacting AppleCare Support
- Appendix C: Using the Command Line
- Installing Apple Qmaster from the Command Line
- Using the Command Line for Distributed Processing
- Using Scripts to Run Apple Qmaster, Compressor, and Batch Monitor
Compressor Native Projects
You can set chapter markers using the Compressor Preview window, but they will not
be preserved when exported to versions earlier than DVD Studio Pro 2. I-frames will be
preserved. If you are using a version prior to DVD Studio Pro 2, you can manually set the
chapter markers directly in DVD Studio Pro.
Things to Consider When Choosing a GOP Setting
You need to consider the following factors when choosing a GOP setting.
GOP Structure
This setting specifies whether there will be two, one, or no B-frames between the reference
frames within a GOP. GOP structure, along with GOP size, determines the number of I-,
P-, and B-frames that will be used during transcoding.
The GOP structure you choose depends on how far apart P-frames should be spaced.
Since a P-frame is predicted from the previous reference frame (either an I-frame or a
P-frame), if there are one or two B-frames in between, the prediction must cover the
distance objects can move over the duration of two to three frames.
In principle, the less average motion there is from one frame to the next, the farther apart
P-frames can be spaced, and the greater the compression can be. For most video material,
the IBBP structure is a good choice. Material with unusually fast motion throughout the
entire sequence may benefit from an IBP or IP structure, but in such cases a relatively
high bit rate (6 to 8 Mbps for SD video) may be required for good quality.
GOP Size
This setting specifies the number of frames within a GOP. Because exactly one I-frame
exists per GOP, longer GOP sizes generally provide greater compression, because B- and
P-frames are smaller than I-frames.
For most media, spacing I-frames about 1/2 second apart gives good results. This equates
to a GOP size of 15 frames for NTSC and 12 frames for PAL. The DVD-Video specification
prohibits GOP lengths from being much longer than this. Generally, only material with
scene changes occurring less than 1/2 second apart frequently throughout the video will
benefit from shorter GOP sizes.
211Chapter 18 Creating MPEG-2 Output Files