Apple prores 422 codecs

About Apple ProRes

Apple ProRes codecs provide an unparalleled combination of multistream, real-time editing performance, impressive image quality, and reduced storage rates. Apple ProRes codecs take full advantage of multicore processing and feature fast, reduced-resolution decoding modes.

All Apple ProRes codecs support all frame sizes (including SD, HD, 2K, 4K, and 5K) at full resolution. The data rates vary based on codec type, image content, frame size, and frame rate. Apple ProRes includes the following formats.

To bring the same performance, quality, and ease of use introduced by Apple ProRes to raw media, use Apple ProRes RAW. Learn more about ProRes RAW.

Apple ProRes 4444 XQ*

Apple ProRes 4444 XQ is the highest-quality version of Apple ProRes for 4:4:4:4 image sources (including alpha channels). This format has a very high data rate to preserve the detail in high-dynamic-range imagery generated by today’s highest-quality digital image sensors. Apple ProRes 4444 XQ preserves dynamic ranges several times greater than the dynamic range of Rec. 709 imagery. This holds true even against the rigors of extreme visual effects processing in which tone-scale blacks or highlights are stretched significantly. Like standard Apple ProRes 4444, this codec supports up to 12 bits per image channel and up to 16 bits for the alpha channel. Apple ProRes 4444 XQ features a target data rate of approximately 500 Mbps for 4:4:4 sources at 1920×1080 and 29.97 fps.

ProRes 4444 XQ is supported on OS X Mountain Lion v10.8 or later.

Apple ProRes 4444*

Apple ProRes 4444 is an extremely high-quality version of Apple ProRes for 4:4:4:4 image sources (including alpha channels). This codec features full-resolution, mastering-quality 4:4:4:4 RGBA color, and visual fidelity that is perceptually indistinguishable from the original material. Apple ProRes 4444 is a high-quality solution for storing and exchanging motion graphics and composites, with excellent multigeneration performance and a mathematically lossless alpha channel of up to 16 bits. This codec features a remarkably low data rate compared to uncompressed 4:4:4 HD. It has a target data rate of approximately 330 Mbps for 4:4:4 sources at 1920×1080 and 29.97 fps. It also offers direct encoding of and decoding to both RGB and Y’C_BC_R pixel formats.

Apple ProRes 422 HQ

Apple ProRes 422 HQ is a higher-data-rate version of Apple ProRes 422 that preserves visual quality at the same high level as Apple ProRes 4444 but for 4:2:2 image sources. With widespread adoption across the video post-production industry, Apple ProRes 422 HQ offers visually lossless preservation of the highest-quality professional HD video that a single-link HD-SDI signal can carry. This codec supports full-width, 4:2:2 video sources at 10-bit pixel depths, while remaining visually lossless through many generations of decoding and reencoding. The target data rate is approximately 220 Mbps at 1920×1080 and 29.97 fps.

Apple ProRes 422

Apple ProRes 422 is a high-quality compressed codec offering nearly all the benefits of Apple ProRes 422 HQ, but at 66 percent of the data rate for even better multistream, real-time editing performance. The target data rate is approximately 147 Mbps at 1920×1080 and 29.97 fps.

Apple ProRes 422 LT

Apple ProRes 422 LT is a more highly compressed codec than Apple ProRes 422, with roughly 70 percent of the data rate and 30 percent smaller file sizes. This codec is perfect for environments where storage capacity and data rate are at a premium. The target data rate is approximately 102 Mbps at 1920×1080 and 29.97 fps.

Apple ProRes 422 Proxy

Apple ProRes 422 Proxy is an even more highly compressed codec than Apple ProRes 422 LT, intended for use in offline workflows that require low data rates but full-resolution video. The target data rate is approximately 45 Mbps at 1920×1080 and 29.97 fps.

* Apple ProRes 4444 and Apple ProRes 4444 XQ are ideal for the exchange of motion graphics media because they are virtually lossless. They are also the only Apple ProRes codecs that support alpha channels.

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Apple ProRes 422 Codec Family

Identification and description

Apple ProRes is a family of proprietary, lossy compressed, high quality video intermediate codecs primarily supported by the Final Cut Pro (FCP) suite of post-production and editing software programs. There are two main branches of Apple ProRes: the Apple ProRes 422 Codec Family (described here) and the Apple ProRes 4444 Codec Family.

The three digits in the name represent the chroma values. Chroma subsampling is usually expressed as a three-part ratio (4:2:2 in the case of ProRes422) although it may also include a fourth part (e.g., 4:4:4:4), when alpha or transparency data is part of the stream as is the case for ProRes4444. As explained in the Wikipedia article Chroma subsampling, the ratio describes the number of luma and chroma samples «in a conceptual region that is J pixels wide, and 2 pixels high.» The three key parts of the ratio are as follows, omitting the alpha channel:

• J: horizontal sampling reference (width of the conceptual region). Usually and in this case: 4.
• a: number of chrominance samples (Cr, Cb) in the first row of J pixels. In this case: 2.
• b: number of (additional) chrominance samples (Cr, Cb) in the second row of J pixels. In this case: 2.

ProRes was designed to be a high quality intermediate codec that keeps post-production workflow data at 10-bit quality, with a bandwidth low enough to be usable for the majority of FCP users.

The key character traits that define the ProRes 422 family are support for:

• 4:2:2 source material (as well as 4:2:1 and 4:2:0 source material if the chroma is upsampled to 4:2:2 prior to encoding),
• any frame size (including SD, HD, 2K, 4K, and 5K) at full resolution,
• 10-bit sample depth,
• intrafame (I-frame) only, and
• variable bit rate.

While ProRes is a 10-bit native codec, it can be used with either 8- or 10-bit sources and 8-bit sources (such as DVCProHD) would need to be upsampled to a 10-bit file.

The Apple ProRes codecs, both the 422 and 4444 families, support both interlaced and progressive scanned images and preserve the scanning method used in the source material. The 422 codecs are differentiated primarily by data rate limits, expected file size ranges and software version support. The 4444 codecs additionally have dynamic range limits (see Notes). Apple provides a summary of the ProRes family technical specifications as well as guidance for selecting appropriate ProRes codecs up to ProRes 4444 based on anticipated workflows. The Apple ProRes family spans a broad range of data rates to support a variety of workflow and application purposes. The authors of this website have selected to use 1920×1080 at 29.97 fps as a comparison target across the ProRes 422 codecs.

ProRes codecs are usually contained within the QuickTime «mov» wrapper but starting with Final Cut Pro 10.3 released on October 27, 2016, the option for using ProRes in the MXF Generic Container was added as an option for broadcast delivery. Previously, MXF import and export was only available through third-party plug-ins starting with version 10.0.6 released in October 23, 2012. See Notes for more information.

While detailed technical information on the ProRes codecs is not freely available directly from Apple, Apple did author a Registered Disclosure Document (RDD) from SMPTE (Society of Motion Picture and Television Engineers) in 2015. RDDs are not engineering documents or standards but rather «are documents within the scope of interest of the Society, submitted by any entity (the “Sponsor” [Apple Inc in this case]) that wishes to make a disclosure available to the public and to use the Society’s publication and distribution mechanisms for this purpose.» SMPTE RDD 36-2015: Apple ProRes Bitstream Syntax and Decoding Process (available for a fee from IEEE) defines the Apple ProRes bitstream syntax, the bitstream element semantics, and the decoding process used to produce decompressed images for the 422 and 4444 ProRes codec families. According to this document, each video frame begins with a frame container atom which details the frame_size and frame_identifier which is always icpf for «image codec prores frame». After the frame container comes the frame header which includes the chroma_format declaring the sampling format of the frame (code value 2 for 4:2:2 and code value 3 for 4:4:4) and the alpha_channel_type field declaring the type of alpha channel data encoded in the bitstream, if any in Table 7. Those coded values are 0 = No encoded alpha data present in bitstream; 1 = 8 bits/sample integral alpha; 2 = 16 bits/sample integral alpha; with values 3-15 reserved for future use. Image data within individual frames starts off with a picture_header containing information about the picture size followed by any number of slices, each with its own slice_header. Figure 2 – ProRes bitstream syntax structure hierarchy on p. 8 gives a helpful visual diagram of this tiered structure. Picture data «are divided into macroblocks and then further into blocks. Macroblocks are 16Г—16 arrays of pixels, and blocks are 8Г—8 arrays of video component samples. For 4:2:2 sampling, each macroblock thus consists of four Y′ (luma) blocks, two Cb blocks, and two Cr blocks; for 4:4:4 sampling, each consists of four Y′ blocks, four Cb blocks, and four Cr blocks. . Finally, the macroblocks of a picture are grouped into slices. Each slice consists of 1, 2, 4, or 8 contiguous macroblocks all in the same macroblock row. . Each slice can be encoded and decoded independently, which facilitates parallel encoding and decoding.»

Full name	Apple ProRes 422 Codec Family
Description
Production phase	Production (initial state) and post production (middle state).
Relationship to other formats
Used by	QTV_AppleProRes422, QuickTime Video, Apple ProRes 422 Codec Family
Has subtype	Apple_ProRes_422_HQ, Apple ProRes 422 High Quality
Has subtype	Apple_ProRes_422, Apple ProRes 422
Has subtype	Apple_ProRes_422_LT, Apple ProRes 422 LT
Has subtype	Apple_ProRes_422_Proxy, Apple ProRes 422 Proxy
Used by	MXF Generic Container Mapped to Apple ProRes 422 Codec Family. Not described at this time
Affinity to	Apple_ProRes_4444_Codec_Family, Apple ProRes 4444 Codec Family
Affinity to	ProRes_RAW_Family, Apple ProRes RAW Codec Family

Local use

LC experience or existing holdings	Apple ProRes 422 Codec Family files appear in Library of Congress collections holdings. See Apple_ProRes_422 and Apple_ProRes_HQ.
LC preference	The Library of Congress Recommended Formats Statement (RFS) lists Apple ProRes 4444, 4444 XQ and 422 HQ in a QuickTime wrapper as a Preferred format for Video — File-Based and Physical Media.

Sustainability factors

The ProRes family is widely adopted in professional moving image production. There is extensive use of the 422 family in the creation of documentaries and other programs for broadcast television. There is some use of the ProRes 4444 family in the production of advertising and in content destined for theatrical distribution. The popularity of Apple’s Final Cut software suite has encouraged uptake of the codecs. Apple ProRes 422 and Apple ProRes 422 HQ were first supported in Final Cut 2 (2001); Apple ProRes 422 Proxy, Apple ProRes 422 LT and Apple ProRes 4444 were added with Final Cut Pro 7 (2009); Apple ProRes 4444 XQ was added to Final Cut Pro X (2012). Apple has licensed Apple ProRes for use in specific products and workflows. Although Apple complains that unauthorized implementations provided by other third-party software and hardware products including FFmpeg «might result in decoding errors, performance degradation, incompatibility, and instability,» this support is a further indicator of adoption.

In November 2015, the New York Times listed ProRes422 as the preferred format for high-resolution assets from video producers, editors, and partners which is later transcoded to a variety of different outputs for specific services including a «single HLS output with six resolutions and bitrates to support adaptive streaming, four different H.264/MP4 outputs, and one VP8/WebM for . users on the Mozilla Firefox browser running on Microsoft Windows XP.»

Apple licenses and certifies specific third party products and workflows. The full list of licensed products is available.

Disclosure	Partially documented. Proprietary format developed by Apple, Inc.
Documentation	Apple provides high level information through its frequently updated ProRes White Paper. More detailed information about the Apple ProRes bitstream syntax, the bitstream element semantics, and the decoding process used to produce decompressed images is available in SMPTE RDD 36-2015: Apple ProRes Bitstream Syntax and Decoding Process which is available for a fee. Multimedia Wiki is another source but this site is not updated regularly.
Adoption
Transparency	Proprietary binary format, requires tools to write and read.
Self-documentation	For AppleProRes422 in QuickTime implementations, technical metadata is in the QuickTime frame container atoms and frame headers which declare the codec type («icpf» for ProRes), frame size and color information (stored in src_pix_fmt). The Multimedia Wiki includes a list of src_pix_fmt values.
External dependencies	None.
Technical protection considerations	None. Comments welcome.

Quality and functionality factors

Potentially excellent depending on the specific codec.

The performance of Apple ProRes codecs scales in multiprocessor environments so that the decoding time per frame goes down as the number of processors increases. When the system spends less time decoding each frame, it has time for more real-time effects processing.

In addition, its scalar quantization allows for the possibility to decode a video at different partial resolutions (ВЅ or Вј etc size of the full frame size) which lowers the data throughput while maintaining high image quality. This functionality allows the user advantages in playback of additional tracks of video and higher quality previews.

File type signifiers and format identifiers

Moving Image
Normal rendering	Supported
Clarity (high image resolution)
Functionality beyond normal rendering

Tag	Value	Note
Filename extension	See note.	The Apple ProRes 422 Codecs are usually contained within the QuickTime «mov» wrapper.
FOURCC	See note.	See individual 422 codecs for FOURCC codes
Pronom PUID	fmt/797	See http://www.nationalarchives.gov.uk/PRONOM/fmt/797. However, the entry for Apple ProRes does not distinguish between ProRes 422 and ProRes 4444 codecs or subtypes.
Wikidata Title ID	Q1136889	See https://www.wikidata.org/wiki/Q1136889. This entry does not distinguish between subtypes of ProRes 422.
Other	ASCII: icpf Hex: 0x69637066	Abbreviation for ‘image codec prores frame’ according to SMPTE RDD 36:2015 which lists this frame type ID in ProRes frame container. This value does not distinguish between ProRes 422 and ProRes 4444 codec families

Notes

The ProRes 422 Family uses a form of discrete cosine transform (DCT) compression. The scalar quantization allows for full frame playback previews from ВЅ or Вј size frame data, lowering the data throughput while maintaining high image quality. This functionality allows the user advantages in playback of additional tracks of video and higher quality previews.

Gary Adcock explains the benefits of ProRes utilizing variable bit rate in this way: «ProRes, being a variable bit rate (VBR) codec, allows the more complex parts of the video to be encoded at a higher bit depth for more detail, while the less complex areas are encoded at a lower bit depth, thereby allowing for overall smaller file sizes [than uncompressed video]. ProRes is approximately a 5.5:1 compression ratio at its maximum and slightly more than 3:1 at its minimum compression level for SD content. This means that despite the quality there is still a fair amount of compression being done on each file.»

Apple’s ProRes White Paper uses peak signal to noise ratio (PSNR) to indicate image quality, stating that PSNR measures «how closely a compressed image (after being decompressed) matches the original image handed to the encoder. The higher the PSNR value, the more closely the encoded image matches the original.» Higher PSNR values also indicates more headroom in the file so that image sequences can be decoded and re-encoded over multiple generations to good effect. In the June 2014 version of the White Paper, a graph on page 13 shows higher PSNR values for a scene encoded as ProRes 422 HQ as compared to the same scene encoded as Avid’s DNxHD and Panasonic’s D5. Another graph on the same page compares four ProRes 422 subtypes, with this comment, «PSNR for Apple ProRes 422 HQ is 15–20 dB higher than that for Apple ProRes 422 Proxy, but the Apple ProRes 422 HQ stream has nearly five times the data rate of the Apple ProRes 422 Proxy stream. The benefit of higher fidelity comes at the cost of larger file sizes.»

The Multimedia Wiki, describes the atom-based structure of ProRes encoded data, a feature that makes them a good fit for the QuickTime file wrapper. The first level is the frame container atom followed by the frame header. The picture data comprises a picture header, which is present for every picture (field), which defines the width and height factors of a slice to inform the decoder how the coded picture is subdivided. The slice index table consists of 16-bit entries — one for each slice — gives the length of the data for each slice, permitting independent processing of the slices in means of multi-threading. Slices data array contains actual encoded macroblock data.

The Apple ProRes 4444 Codec Family, which includes Apple ProRes 4444 and Apple ProRes 4444 XQ, is seeing some use in the creation of productions destined for theaters and high end advertising. The fourth «4» in the name indicates this format’s support for alpha (transparency) data, in contrast to ProRes 422. Other features include picture sizes ranging as high as 5K and 4:4:4 chroma subsampling up to 12-bits per sample. Alpha channel sampling can be as high as 16-bits.

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