MPEG-2 setting in Compressor
The built-in MPEG Files settings in Compressor use the MPEG-2 transcoding format. (The MPEG-2 for DVD setting in the Create DVD destination also uses this format.) Use this format to encode MPEG-2 stream files for DVD and Blu-ray authoring.
Note: You can also create custom settings that use the MPEG-2 transcoding format. However, the built-in MPEG-2 settings (in the Settings pane) analyze your source media and assign optimal properties to ensure the best possible transcoding results.
The built-in MPEG-2 for DVD setting encodes only a video file. To encode the accompanying audio, use the Dolby Digital audio setting. The easiest way to do this is to apply the Create DVD destination to your source file, which adds both the MPEG-2 for DVD setting and the Dolby Digital setting to your job. For more information, see Dolby Digital settings in Compressor.
The properties of built-in and custom settings that use this transcoding format are located in the General, Video, and Audio inspectors (described below).
Displays the setting name and transcoding format used by Compressor, as well as an estimated output file size. When you add a setting to a job or change the setting’s properties, this summary is automatically updated.
Name: Displays the name of the setting.
Description: Displays the description of the setting.
Extension: Displays the extension of the output file.
Allow job segmenting: If you’ve set up distributed processing, select this checkbox to have Compressor process the output file using your shared computer group. See Transcode batches with multiple computers using Compressor.
Default location: Select an item from the pop-up menu to set the default save location for transcoded files.
Format: Use the pop-up menu to set the stream type for the output file. There are three options:
Program Stream: This stream type contains only one MPEG-2 content channel and its associated audio. Program streams require an error-free delivery method and are primarily used for storage or processing within a computer.
Elementary Stream: This stream type contains only one MPEG-2 content channel and no audio. When you select this option, you should also set the “Stream usage” property.
Transport Stream: This stream type can contain several MPEG-2 content channels and associated audio. All the channels are multiplexed together, allowing the receiver to choose which to play back. Compressor supports creating single-channel transport streams that can also include associated audio. Transport streams can also recover from interruptions during playback, making them ideally suited for broadcast and streaming applications where noise or network congestion can lead to interruptions.
Stream usage: Use this pop-up menu to specify the MPEG-2 transcoding output. Compressor modifies the available properties based on the option you choose:
Generic: This option allows you complete access to all the MPEG-2 properties. This is the only option that supports the MPEG-2 640 x 480 video format in addition to the standard-definition (SD) and high-definition (HD) video formats. It’s also the only option that supports creating transport and program streams. It supports the complete bit rate range of 2.0 Mbps to 40.0 Mbps.
DVD: This option restricts the encoding properties to those allowed by the SD DVD specification. These include the NTSC and PAL video formats and a bit rate range of 2.0 Mbps to 9.0 Mbps.
Blu-ray: This option restricts the encoding properties to those allowed by Blu-ray video discs. These include the SD and HD video formats and a bit rate range of 10.0 Mbps to 40.0 Mbps.
Add Apple metadata: Select this checkbox to have Compressor parse specific MPEG-2 authoring information during the transcoding process and provide it in the output file. The resulting file will be read faster by other applications.
Include chapter markers only: Select this checkbox to include chapter markers, but not unnamed compression markers, in MPEG-2 output. When this checkbox is deselected, all markers are included in the output file. See Add markers using Compressor.
This area contains one property:
Set duration to: Sets the processing algorithm used to adjust the frame rate during transcoding. Select one of the following options:
[Percentage] of source: Modifies the output clip’s speed by a percentage of the source clip’s speed. Enter a value in the percentage field or choose a preset value from the adjacent pop-up menu (with a down arrow).
[Total duration]: Sets the duration of the clip. Enter a timecode duration in the field or click the arrows to increase or decrease the time.
So source frames play at [frame rate] fps: Nondestructively changes the playback speed of the clip, without discarding frames or creating new frames. This property has no effect unless the “Frame rate” value in the Video inspector is different from the source file’s frame rate. For example, if you add a 10-second source file with a frame rate of 24 fps to Compressor, set the “Frame rate” property in the Video inspector to 25 fps, then select “So source frames play at 25 fps” in the General inspector, the duration of the transcoded clip (at 25 fps) is 9 seconds and 15 frames.
For more information, see Retime video and audio using Compressor.
This area contains a single property, the “Embed closed captions” checkbox. Select the checkbox if you’ve added CEA-608 closed captions to a job and you want Compressor to insert the captions into the output video file. See How Compressor supports captions.
Frame size: Use the pop-up menu to set the frame size (resolution) for the output file.
Pixel aspect ratio: Use this pop-up menu to set the pixel aspect ratio (the ratio between the encoded width and the display width).
Frame rate: Use this pop-up menu to set the playback rate (the number of images displayed per second) for the output file. See Retiming options in Compressor.
Field order: Use the pop-up menu to set the output scanning method (either the field dominance or a conversion to progressive scanning). There are four options:
Automatic: Selects the most appropriate field order, based on the field order of the source and the capabilities of the selected codec.
Progressive: The video is displayed in complete frames with all lines sampled at the same instant in time.
Top First: The video is interlaced and displayed as two separate interleaved fields. The field containing the top line (even lines) is sampled at an earlier instant in time than the field containing the bottom line (odd lines). This field order is commonly used for high-definition video and standard-definition PAL video.
Bottom First: The video is interlaced and displayed as two separate interleaved fields. The field containing the bottom line (odd lines) is sampled at an earlier instant in time than the field containing the top line (even lines). This field order is commonly used for standard-definition NTSC video.
Color space: Use this pop-up menu to convert the source media to a new color space. Choose Automatic to allow Compressor to choose the best color space based on the selected preset. You can also choose a manual setting to override the default.
Anamorphic: This property applies only to standard-definition video. If the source video’s storage aspect ratio doesn’t match its display aspect ratio, you can correct the image so the output doesn’t appear squeezed or stretched. Choose Automatic from the pop-up menu to have Compressor scale the image based on the frame size, or choose 16:9 or 4:3 to scale the image to a specific aspect ratio.
Encoding mode: Choose an option from the pop-up menu to set how Compressor encodes the output file: either faster and lower quality, or slower and better quality. Options include:
Single Pass CBR: This is the fastest MPEG-2 encoding mode. It provides good quality, especially at bit rates between 5 and 9 Mbps.
Single Pass VBR: This mode aims to maintain constant quality (at the expense of constant bit rate) for the transcoded video file. For most standard-definition (SD) media files at bit rates of 3.5 Mbps and above, this mode provides good to excellent quality and transcodes quickly.
Single Pass VBR (Best): This mode provides the best possible quality output for SD video at bit rates of 3 to 3.5 Mbps and above.
Two Pass VBR: This mode uses two passes—one pass to analyze the entire source video stream, and a second pass to compress the file. This mode takes longer and provides a better-quality file than the one-pass modes, and is recommended for source media files with a substantial difference between the most and the least complex scenes.
Two Pass VBR (Best): This mode provides the best possible quality output, and outstanding quality at bit rates of 3 to 3.5 Mbps and above for HD and SD video.
Motion estimation: This pop-up menu sets the amount of motion processing that will be performed on the file. There are three options:
Good: The fastest processing setting. Use this setting when there is relatively low motion between frames. In general, use Good with the one-pass encoding modes.
Better: Provides very good results even in the presence of complex interlaced motion. In general, use Better with Single Pass VBR (Best) and Two Pass VBR (Best).
Best: The slowest processing setting. Use for the most complex motion and for interlaced source files. In general, use the Best mode to maximize quality when using Single Pass VBR (Best) or Two Pass VBR (Best).
GOP structure: This property is available only when the “Frame rate” property is set manually (does not use Automatic).
Compressor provides three methods of grouping frames, or “pictures,” in encoded video: as I-frames (intra-frames), P-frames (predictive frames), and B-frames (bidirectional predictive frames). These are collectively called a group of pictures (GOP). The “GOP structure” pop-up menu includes several methods of arranging frames:
IP: Use IP only if your media contains fast motion that isn’t encoded with sufficient quality using an IBBP or IBP structure.
IBP: Use IBP only if your media contains fast motion that isn’t encoded with sufficient quality using an IBBP structure.
IBBP: Recommended for the majority of MPEG-2 encoding situations.
Note: For most MPEG-2 encoding situations intended for use on a DVD, choose IBBP as the GOP structure setting, and a GOP size of 15 for NTSC, or 12 for PAL.
GOP size: This property is available when the “Frame rate” property is set manually (does not use Automatic).
This slider specifies how many frames are contained within a GOP (group of pictures). The values available in the slider are determined by the GOP structure property (described above). The maximum GOP size you can choose within Compressor is 15 frames (NTSC) or 12 frames (PAL and 720p). The minimum GOP size for all video formats is 6 frames (closed GOP) or 7 frames (open GOP).
Automatically select bit rate: Select this checkbox to have Compressor automatically compute the best bit rate for the output file, based on the duration of the source file. To manually adjust the bit rate, deselect the checkbox and drag the “Average bit rate” and “Maximum bit rate” sliders (or enter values in the adjacent fields).
YUV 422 color encoding: This property appears in most built-in settings that output MPEG-2 files. Select this checkbox to use YUV 422 color encoding for superior chroma quality.
Cropping and padding
Customize the final cropping, sizing, and aspect ratio using the Cropping & Padding properties in Compressor. Cropping removes video content from an image. Padding scales the image to a smaller size while retaining the output image’s frame size. For more information about these properties, see Intro to modifying frame size in Compressor.
Cropping: This pop-up menu sets the dimension of the output image. The custom option allows you to enter your own image dimensions in the fields; other options use predetermined sizes. The Letterbox Area of Source option detects image edges and automatically enters crop values to match them. This is useful if you want to crop out the letterbox area (the black bars above and below a widescreen image) of a source media file.
Padding: This pop-up menu sets the scaling of the output image while retaining the output image’s frame size. The custom option allows you to enter your own scaling dimensions in the fields; other options use predetermined dimensions.
The following properties determine how Compressor resizes, retimes, and otherwise adjusts the video when transcoded:
Resize filter: This pop-up menu sets the resizing method. There are several options:
Nearest Pixel (Fastest): Samples the nearest neighboring pixel when resizing an image. This option provides the fastest processing time, but it is more likely to show aliasing artifacts and jagged edges.
Linear: Adjacent pixel values are averaged using a linear distribution of weights. Produces fewer aliasing artifacts than Nearest Pixel, with a small increase in processing time.
Gaussian: Adjacent pixel values are averaged using a gaussian distribution of weights. This provides a medium trade-off between processing time and output quality.
Lanczos 2: Adjacent pixel values are averaged using a truncated sinc function. This option is slower than Gaussian but provides sharper results.
Lanczos 3: Similar to Lanczos 2 but averages more pixel values. This option is slower than Lanczos 2 but may produce better results.
Bicubic: Adjacent pixel values are averaged using a bicubic function. The processing time and output are most similar to Lanczos 2 and Lanczos 3.
Anti-aliased (Best): Provides the highest output quality, but can take substantially longer to process.
Retiming Quality: This pop-up menu sets the retiming method. There are four options:
Fast (Nearest Frame): Linearly interpolates frames using nearest neighbor frames.
Good (Frame Blending): Blends neighboring frames using a filter to produce good-quality interpolation.
Best (Motion Compensated): Uses optical flow to interpolate using areas of movement between neighboring frames to produce high-quality output.
Reverse Telecine: Removes the extra fields added during the telecine process to convert the film’s 24 fps to NTSC’s 29.97 fps. Choosing this item disables all the other Quality controls. See Use reverse telecine in Compressor.
Adaptive details: Select this checkbox to use advanced image analysis to distinguish between noise and edge areas during output.
Anti-aliasing level: Sets the softness level in the output image. Double-click the value and then manually enter a new value or drag the slider to the right to increase softness. This property improves the quality of conversions when you’re scaling media up. For example, when transcoding SD video to HD, anti-aliasing smooths jagged edges that might appear in the image.
Details level: Sets the amount of detail in the output image. Double-click the value and then manually enter a new value or drag the slider to set the value. This sharpening control lets you add detail back to an image being enlarged. Unlike other sharpening operations, the “Details level” property distinguishes between noise and feature details, and generally doesn’t increase unwanted grain. Increasing this value may introduce jagged edges, however, which can be eliminated by increasing the “Anti-aliasing level” slider.
Dithering: When selected, adds a certain type of noise to images to prevent large-scale distracting patterns such as color banding. If your image has excessive noise after rendering, deselect this checkbox.
For a list of available video effects in Compressor, and instructions on how to add a video effect to a setting, see Add and remove effects in Compressor.