MPEG-4 settings in Compressor
In Compressor, 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 HTTP Live Streaming and other related documents, available in Apple Developer Documentation.)
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, iPadOS 13 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 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 (.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. See Transcode batches with multiple computers using Compressor.
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. If format is set to Audio, audio-only files are created with the .m4a extension, and you can choose Apple Lossless or AAC output. If format is set to Audio and Video or Video, files are created with the .m4v extension.
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. See Add metadata annotations in Compressor and 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.
Note: This option is not available when outputting an MPEG-4 audio file.
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 Intro to supporting captions in Compressor.
Some video properties are enabled only for codecs that support them. If a video property is disabled in Compressor, it’s not supported by the selected codec.
Frame size: Use this pop-up menu to set the frame size (resolution) for the output file. There are four categories to choose from:
Automatic: Adjusts the output based on the size of the input, and can be constrained "up to” a maximum resolution.
Percentage: Adjusts the output based on a percentage of the input’s size.
Manual: Forces the output to a specific resolution.
Constrained: Constrains the output to a specific aspect ratio.
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, 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 Intro to wide color gamut and HDR in Compressor.
RAW to log: Use this pop-up menu to select how ProRes RAW conversion is done. Choose Automatic to allow Compressor to choose the conversion method. You can also choose a manual setting to override the default. This option is available only if the source is ProRes RAW.
Camera LUT: Use this pop-up menu to select the camera lookup table (LUT) applied to the source. Select a custom LUT to transform your video from one color space to another. This setting is enabled if the source is ProRes RAW and if “RAW to log” is set to a value other than None. This setting is also enabled if “Camera log” in video properties in the Job inspector is set to a value other than None.
Codec: Choose one of two available transcoding formats, H.264 or HEVC.
Encoder type: Use this pop-up menu to set the type of encoder. This pop-up menu is enabled when Codec is set to HEVC. Choose from two options:
Faster (standard quality): Encodes the output file using a faster codec, with standard quality.
Slower (higher quality): Encodes the output file using a slower codec, with higher quality.
Important: Not all options are available on all hardware.
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 and more compatible for playback on older devices).
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).
Quality: Use this slider to set the quality level of your output. Select from least (smaller file size) to best (larger file size).
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.
Include Dolby Vision 8.4 metadata: Select this checkbox to have Compressor include Dolby Vision 8.4 metadata in the output file. Dolby Vision 8.4 is a format designed to optimize HDR content for Apple devices. If this checkbox is selected, “Color space” is set to Rec. 2020 HLG, Codec is set to HEVC, and Profile is set to 10-Bit Color.
Allow frame reordering: Select this checkbox to potentially provide a better-quality output file by allowing Compressor to reorder video frames during transcoding. This option is available only when Codec is set to H.264 or HEVC.
Important: If you select “Allow frame reordering,” your output file may be more efficiently compressed but may not be compatible with decoders on older hardware.
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 and Vimeo.
Spherical Video V2: A less common, but more up-to-date, 360° metadata format used by YouTube and Vimeo.
For more information, see View 360° video metadata using Compressor.
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.
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.
Quality: Use this pop-up menu to select the quality of the audio output.
Bit rate: Use this pop-up menu to set the bit rate for the encoded audio.
Bit rate strategy: Use this pop-up menu to select the strategy used to encode the audio. There are four options:
Constant bit rate: Uses the value set in “Bit rate” to determine the bit rate for the encoded audio.
Average bit rate: Uses the value set in “Bit rate” to determine the target average bit rate for the encoded audio. This option provides a more consistent bit rate than variable bit rate.
Variable bit rate constrained: Uses the value set in “Bit rate” to determine the maximum bit rate for the encoded audio.
Variable bit rate: Encodes the audio using a variable bit rate determined by Compressor.
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 in Compressor, and instructions on how to add an audio effect to a setting, see Add and remove effects in Compressor.