V_data_size = slice_data_size from slice index table - luma_data_size - u_data_size - (slice_hdr_size / 8) Įvery codeword is encoded as Rice code with three parameters defining coding parameters: maximum prefix length for Rice codes ( MP), Rice code parameter ( R) and Elias gamma (aka exp-Golomb) code parameter ( G).ĭecoding process is the following: read unary prefix, if its value more than MP then treat code as Elias gamma, otherwise treat it as Rice code (or pure unary for R=0). Scale factor for scaling the quantization matrices (see below).Īlthough, the length of the chroma V data is not indcated in the slice header, it can be easily calculated as follows: Thus, only one slice height = 1 macroblock is supported. Ideally slice height = 2 ^ slice_height_factor but in all known decoders only the value of "0" for that factor is allowed. Supported slice sizes are therefore 8, 4, 2 and 1 macroblocks wide.
Must be at least 64 bits (8 bytes) long.Īt the same times it indicates the number of entries in the slice table. This header is present for every picture (field). Slices data array contains actual encoded macroblock data.
Thus, it permits independent processing of the slices in means of multi-threading. Slice index table consists of 16bit entries - one for each slice - giving the length of the data for each slice.
Therefore, those tell the decoder how the coded picture is subdivided. The picture header contains two important parameters: width and height factors of a slice. Only present if indicated by the bit "D" of the QMatFlags. Only present if indicated by the bit "C" of the QMatFlags.Ĭustom quantization matrix for chrominance. bit D = 1 -> custom chroma quant matrix presentĬustom quantization matrices presence indicators.Ĭustom quantization matrix for luminance.bit C = 1 -> custom luma quant matrix present.Used in combination with alpha channel coding. "6" = ITU-R BT.601-4 / SMPTE 170M-1994 / SMPTE 293M-1996Ĭolor matrix ID for color conversion between YUV and RGB (see below).Transfer function of the coded image (see the description of the 'nclc' extension by Apple). bits AA = chrominance factor (picture format):Ĭolor primaries of the coded image (see the description of the 'nclc' extension by Apple).'arri' -> Arnold & Richter Cine Technik (A&R)įOURCC of the creator of the present stream."1" - supported in the version 2.0 only.
The value of the field "size" must match frame size from the movie container.Ī frame header stores description information, such as frame dimension, frame structure (progressive/interlaced), color information and the like.Īll data is stored in the big-endian format. It has the classical QuickTime atom structure with the ID set to the undocumented ProRes frame type ID:Īll data is stored in the big-endian format. ProRes codec is currently available as the following binary libraries:Ī typical ProRes 422 frame has the following layout:Īt the beginning of each frame the frame container atom is located. ProRes is capable of saving CPU cycles while decoding at smaller resolutions due to a special bitstream layout enabling partial bitstream access and parsing.
spatial scalability providing the possibility to decode a video at different partial resolutions (1/2, 1/4, 1/8 of the full size and so on).frame-level multi-threaded encoding/decoding depending on available CPU cores.The bitstream of the ProRes 422 has been designed to provide the following additional features: custom hybrid Golomb-Rice / Exponential Golomb coding for DCT coefficients.ProRes algorithm is based on the Discrete cosine transform (further DCT) and utilizes the following compression techniques: Two different FOURCCs are used in order to indicate each flavour: ProRes 422 SD/HQ is the same codec operating on two different bitrates (flavours).
ProRes 422 Standard Definition / High Quality codec 10-bit (12-bit for ProRes 4444) sample depth.compressed images cannot be distinguished from the original by a human observer) Apple's official whitepaper lists the codec's key features as being: 2 ProRes 422 Standard Definition / High Quality codecĪpple ProRes is a family of proprietary video codecs used for storing and editing high definition video data in Apple's Final Cut Pro.