The Prepare for HTTP Live Streaming destination and the AAC setting (for audio output) use the MPEG-4 transcoding format. The MPEG-4 format is widely compatible with many different platforms and is often used for distribution on the Internet. You can also use this format to create files for audio podcasting and digital music playback. (To learn more about HTTP Live Streaming, see the HTTP Live Streaming Overview and other related documents, available in the Mac Developer Library.)
Settings based on the MPEG-4 format offer a choice of two encoders: H.264 and HEVC (High-Efficiency Video Coding, also known as H.265). When you add an MPEG-4-based setting to a job, Compressor chooses the H.264 format as the default codec. You can change the codec to HEVC in the Video inspector if your computer is running macOS 10.13 or later. HEVC is a recently established compression standard that supports larger frame sizes (including 8K) and HDR10 metadata for high-dynamic-range video. HEVC playback requires a recent-generation Apple device running macOS 10.13 or later, iOS 11 or later, or tvOS 11 or later.
Note: You can also create custom settings that use the MPEG-4 transcoding format. However, the built-in settings (in the Settings pane) analyze your source media and assign optimal properties to ensure the best possible transcoding results.
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, as well as an estimated output file size. When you add a setting to a job or change the setting’s properties, this summary automatically updates.
Name: Displays the name of the setting.
Description: Displays the description of the setting.
Extension: Displays the extension of the output file (.mp4 or .m4a).
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. For more information, see Transcode batches with multiple computers.
Note: Job segmenting is not available when outputting an MPEG-4 audio file or when the Multi-pass checkbox is selected in the Video inspector.
Default location: Choose an item from the pop-up menu to set the default save location for transcoded files.
Format: Use this pop-up menu to specify whether the output includes video and audio, video only, or audio only. For podcasting and digital music playback, choose audio only.
Optimize for network use: Select this checkbox to create a file that will start playing after only a small portion of the file has been downloaded from the network.
Enhanced podcast: Select this checkbox to have Compressor embed podcasting information (annotations, markers, and artwork) into the output media file. For more information about annotations, see Add metadata. For more information about chapter markers, see Add markers.
This section 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.
Note: This option is not available when outputting an MPEG-4 audio file.
For more information, see Retime video and audio.
Frame size: Use the pop-up menu to set the frame size (resolution) for the output file.
Pixel aspect ratio: Use the pop-up menu to set the pixel aspect ratio (the ratio between the image frame width and height). You can also modify the aspect ratio of the output file using cropping and padding properties. For more information, see Modify frame size overview.
Frame rate: Use this pop-up menu to set the playback rate (the number of images displayed per second) for the output file. For more information, see Retiming options overview.
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:
Same as Source: Maintains the same scanning method used by the source media file.
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, including wide color gamut. 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. For more information about wide color gamut, see About wide color gamut and HDR.
Codec: Choose one of two available transcoding formats, H.264 or HEVC.
Profile: Use this pop-up menu to set the quality of compression used in the output file. When Codec is set to H.264, this pop-up menu offers three options:
High: Provides high-quality output, which may not be compatible with older H.264 playback devices.
Main: Similar to the Baseline profile, with additional support for standard-definition (SD) video requirements.
Baseline: Primarily for video conferencing and mobile applications.
When Codec is set to HEVC, the Profile pop-up menu sets the color depth of the output file (the number of bits used to represent color in each color channel—red, green, and blue). There are two options:
8-Bit Color: Provides a good balance between picture quality and file size. (This option is available only on recent Mac computers that support hardware encoding of HEVC.)
10-Bit Color: Provides better picture quality but with larger file sizes. (Because this option uses software encoding, performance may be significantly slower than 8-bit hardware encoding.)
Entropy mode: When Codec is set to H.264, use this pop-up menu to set the entropy mode to CABAC (which provides higher-quality output) or CAVLC (which is faster). This control is disabled when Codec is set to HEVC.
Key frame interval: Enter a value in the text field to set the key frame interval (number of frames) at which you want key frames created in your output file. Alternatively, you can select Automatic to have Compressor choose the key frame interval rate (the displayed value is 0 with Automatic on; the actual value is determined during the encoding process).
Data rate: This pop-up menu allows you to choose a data rate for your video based on any of three options:
Custom: Enables a slider to set the number of kilobits per second (kbps) to which you want to limit your video signal. Higher rates allow higher-quality video, but generate larger files that are slower to download or transmit.
Computer playback: Creates a larger file with higher quality.
Web publishing: Creates a smaller file (of lower quality) suitable for hosting on a website.
Important: When you set a data rate, you override other codec-quality properties because the codec compresses the file as much as it needs to based on its data-rate limit.
Multi-pass: Select this checkbox to turn on multi-pass encoding that uses additional analysis of video frames to produce a high-quality output file. For faster (single-pass) transcoding, turn this feature off by deselecting the checkbox.
Allow frame reordering: Select this checkbox to potentially provide a better-quality output file by allowing Compressor to reorder video frames during transcoding.
360° metadata: Use this pop-up menu to choose the type of 360° metadata, if any, included in the output file.
Automatic: Compressor chooses the metadata format based on the properties in the Job inspector and the transcode setting you applied. The format chosen is listed to the right of the pop-up menu.
None: No 360° metadata is attached to your output file.
Spherical Video V1: The 360° metadata format most commonly used by sharing sites, including YouTube, Vimeo, and Facebook.
Spherical Video V2: A less common, but more up-to-date, 360° metadata format used by YouTube and Vimeo.
For more information, see Assign 360° video metadata.
Customize the final cropping, sizing, and aspect ratio using the Cropping & Padding properties. 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 Modify frame size overview.
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 the video will be resized, retimed, and otherwise adjusted 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. For more information, see About reverse telecine.
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 and instructions on how to add a video effect to a setting, see Add and remove effects.
Channel layout: Use the pop-up menu to set the audio channel layout.
Sample rate: Use this pop-up menu to set the number of times per second that music waveforms (samples) are captured digitally. The higher the sample rate, the higher the audio quality and the larger the file size.
Data rate: Use the slider to set the number of kilobits per second (kbps) required to deliver your audio file. Using a higher rate will produce a higher-quality audio file.
For a list of available audio effects and instructions on how to add an audio effect to a setting, see Add and remove effects.