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diff --git a/docs/formats.md b/docs/formats.md new file mode 100644 index 00000000..12ea9465 --- /dev/null +++ b/docs/formats.md @@ -0,0 +1,208 @@ +# Introduction + +Formats (FOURCC) supported by libyuv are detailed here. + +# Core Formats + +There are 2 core formats supported by libyuv - I420 and ARGB. + All YUV formats can be converted to/from I420. + All RGB formats can be converted to/from ARGB. + +Filtering functions such as scaling and planar functions work on I420 and/or ARGB. + +# OSX Core Media Pixel Formats + +This is how OSX formats map to libyuv + + enum { + kCMPixelFormat_32ARGB = 32, FOURCC_BGRA + kCMPixelFormat_32BGRA = 'BGRA', FOURCC_ARGB + kCMPixelFormat_24RGB = 24, FOURCC_RAW + kCMPixelFormat_16BE555 = 16, Not supported. + kCMPixelFormat_16BE565 = 'B565', Not supported. + kCMPixelFormat_16LE555 = 'L555', FOURCC_RGBO + kCMPixelFormat_16LE565 = 'L565', FOURCC_RGBP + kCMPixelFormat_16LE5551 = '5551', FOURCC_RGBO + kCMPixelFormat_422YpCbCr8 = '2vuy', FOURCC_UYVY + kCMPixelFormat_422YpCbCr8_yuvs = 'yuvs', FOURCC_YUY2 + kCMPixelFormat_444YpCbCr8 = 'v308', FOURCC_I444 ? + kCMPixelFormat_4444YpCbCrA8 = 'v408', Not supported. + kCMPixelFormat_422YpCbCr16 = 'v216', Not supported. + kCMPixelFormat_422YpCbCr10 = 'v210', FOURCC_V210 previously. Removed now. + kCMPixelFormat_444YpCbCr10 = 'v410', Not supported. + kCMPixelFormat_8IndexedGray_WhiteIsZero = 0x00000028, Not supported. + }; + + +# FOURCC (Four Charactacter Code) List + +The following is extracted from video_common.h as a complete list of formats supported by libyuv. + enum FourCC { + // 10 Primary YUV formats: 5 planar, 2 biplanar, 2 packed. + FOURCC_I420 = FOURCC('I', '4', '2', '0'), + FOURCC_I422 = FOURCC('I', '4', '2', '2'), + FOURCC_I444 = FOURCC('I', '4', '4', '4'), + FOURCC_I400 = FOURCC('I', '4', '0', '0'), + FOURCC_NV21 = FOURCC('N', 'V', '2', '1'), + FOURCC_NV12 = FOURCC('N', 'V', '1', '2'), + FOURCC_YUY2 = FOURCC('Y', 'U', 'Y', '2'), + FOURCC_UYVY = FOURCC('U', 'Y', 'V', 'Y'), + FOURCC_H010 = FOURCC('H', '0', '1', '0'), // unofficial fourcc. 10 bit lsb + FOURCC_U010 = FOURCC('U', '0', '1', '0'), // bt.2020, unofficial fourcc. + // 10 bit lsb + + // 1 Secondary YUV format: row biplanar. + FOURCC_M420 = FOURCC('M', '4', '2', '0'), // deprecated. + + // 13 Primary RGB formats: 4 32 bpp, 2 24 bpp, 3 16 bpp, 1 10 bpc, 2 64 bpp + FOURCC_ARGB = FOURCC('A', 'R', 'G', 'B'), + FOURCC_BGRA = FOURCC('B', 'G', 'R', 'A'), + FOURCC_ABGR = FOURCC('A', 'B', 'G', 'R'), + FOURCC_AR30 = FOURCC('A', 'R', '3', '0'), // 10 bit per channel. 2101010. + FOURCC_AB30 = FOURCC('A', 'B', '3', '0'), // ABGR version of 10 bit + FOURCC_AR64 = FOURCC('A', 'R', '6', '4'), // 16 bit per channel. + FOURCC_AB64 = FOURCC('A', 'B', '6', '4'), // ABGR version of 16 bit + FOURCC_24BG = FOURCC('2', '4', 'B', 'G'), + FOURCC_RAW = FOURCC('r', 'a', 'w', ' '), + FOURCC_RGBA = FOURCC('R', 'G', 'B', 'A'), + FOURCC_RGBP = FOURCC('R', 'G', 'B', 'P'), // rgb565 LE. + FOURCC_RGBO = FOURCC('R', 'G', 'B', 'O'), // argb1555 LE. + FOURCC_R444 = FOURCC('R', '4', '4', '4'), // argb4444 LE. + + // 1 Primary Compressed YUV format. + FOURCC_MJPG = FOURCC('M', 'J', 'P', 'G'), + + // 11 Auxiliary YUV variations: 3 with U and V planes are swapped, 1 Alias. + FOURCC_YV12 = FOURCC('Y', 'V', '1', '2'), + FOURCC_YV16 = FOURCC('Y', 'V', '1', '6'), + FOURCC_YV24 = FOURCC('Y', 'V', '2', '4'), + FOURCC_YU12 = FOURCC('Y', 'U', '1', '2'), // Linux version of I420. + FOURCC_J420 = FOURCC('J', '4', '2', '0'), + FOURCC_J400 = FOURCC('J', '4', '0', '0'), // unofficial fourcc + FOURCC_H420 = FOURCC('H', '4', '2', '0'), // unofficial fourcc + FOURCC_H422 = FOURCC('H', '4', '2', '2'), // unofficial fourcc + FOURCC_U420 = FOURCC('U', '4', '2', '0'), // bt.2020, unofficial fourcc + FOURCC_U422 = FOURCC('U', '4', '2', '2'), // bt.2020, unofficial fourcc + FOURCC_U444 = FOURCC('U', '4', '4', '4'), // bt.2020, unofficial fourcc + + // 14 Auxiliary aliases. CanonicalFourCC() maps these to canonical fourcc. + FOURCC_IYUV = FOURCC('I', 'Y', 'U', 'V'), // Alias for I420. + FOURCC_YU16 = FOURCC('Y', 'U', '1', '6'), // Alias for I422. + FOURCC_YU24 = FOURCC('Y', 'U', '2', '4'), // Alias for I444. + FOURCC_YUYV = FOURCC('Y', 'U', 'Y', 'V'), // Alias for YUY2. + FOURCC_YUVS = FOURCC('y', 'u', 'v', 's'), // Alias for YUY2 on Mac. + FOURCC_HDYC = FOURCC('H', 'D', 'Y', 'C'), // Alias for UYVY. + FOURCC_2VUY = FOURCC('2', 'v', 'u', 'y'), // Alias for UYVY on Mac. + FOURCC_JPEG = FOURCC('J', 'P', 'E', 'G'), // Alias for MJPG. + FOURCC_DMB1 = FOURCC('d', 'm', 'b', '1'), // Alias for MJPG on Mac. + FOURCC_BA81 = FOURCC('B', 'A', '8', '1'), // Alias for BGGR. + FOURCC_RGB3 = FOURCC('R', 'G', 'B', '3'), // Alias for RAW. + FOURCC_BGR3 = FOURCC('B', 'G', 'R', '3'), // Alias for 24BG. + FOURCC_CM32 = FOURCC(0, 0, 0, 32), // Alias for BGRA kCMPixelFormat_32ARGB + FOURCC_CM24 = FOURCC(0, 0, 0, 24), // Alias for RAW kCMPixelFormat_24RGB + FOURCC_L555 = FOURCC('L', '5', '5', '5'), // Alias for RGBO. + FOURCC_L565 = FOURCC('L', '5', '6', '5'), // Alias for RGBP. + FOURCC_5551 = FOURCC('5', '5', '5', '1'), // Alias for RGBO. + +# Planar YUV + The following formats contains a full size Y plane followed by 1 or 2 + planes for UV: I420, I422, I444, I400, NV21, NV12, I400 + The size (subsampling) of the UV varies. + I420, NV12 and NV21 are half width, half height + I422, NV16 and NV61 are half width, full height + I444, NV24 and NV42 are full width, full height + I400 and J400 have no chroma channel. + +# Color space + The YUV formats start with a letter to specify the color space. e.g. I420 + I = BT.601 limited range + J = BT.601 full range (J = JPEG that uses this) + H = BT.709 limited range (H for HD) + F = BT.709 full range (F for Full range) + U = BT.2020 limited range (U for UHD) + V = BT.2020 full range + For YUV to RGB conversions, a matrix can be passed. See also convert_argh.h + +# HDR formats + Planar formats with 10 or 12 bits use the following fourcc: + I010, I012, P010, P012 are half width, half height + I210, I212, P210, P212 are half width, full height + I410, I412, P410, P412 are full width, full height + where + I is the color space (see above) and 3 planes: Y, U and V. + P is a biplanar format, similar to NV12 but 16 bits, with the valid bits in the high bits. There is a Y plane and a UV plane. + 0, 2 or 4 is the last digit of subsampling: 4:2:0, 4:2:2, or 4:4:4 + 10 or 12 is the bits per channel. The bits are in the low bits of a 16 bit channel. + +# The ARGB FOURCC + +There are 4 ARGB layouts - ARGB, BGRA, ABGR and RGBA. ARGB is most common by far, used for screen formats, and windows webcam drivers. + +The fourcc describes the order of channels in a ***register***. + +A fourcc provided by capturer, can be thought of string, e.g. "ARGB". + +On little endian machines, as an int, this would have 'A' in the lowest byte. The FOURCC macro reverses the order: + + #define FOURCC(a, b, c, d) (((uint32)(a)) | ((uint32)(b) << 8) | ((uint32)(c) << 16) | ((uint32)(d) << 24)) + +So the "ARGB" string, read as an uint32, is + + FOURCC_ARGB = FOURCC('A', 'R', 'G', 'B') + +If you were to read ARGB pixels as uint32's, the alpha would be in the high byte, and the blue in the lowest byte. In memory, these are stored little endian, so 'B' is first, then 'G', 'R' and 'A' last. + +When calling conversion functions, the names match the FOURCC, so in this case it would be I420ToARGB(). + +All formats can be converted to/from ARGB. + +Most 'planar_functions' work on ARGB (e.g. ARGBBlend). + +Some are channel order agnostic (e.g. ARGBScale). + +Some functions are symmetric (e.g. ARGBToBGRA is the same as BGRAToARGB, so its a macro). + +ARGBBlend expects preattenuated ARGB. The R,G,B are premultiplied by alpha. Other functions don't care. + +# RGB24 and RAW + +There are 2 RGB layouts - RGB24 (aka 24BG) and RAW + +RGB24 is B,G,R in memory +RAW is R,G,B in memory + +# AR30 and XR30 + +AR30 is 2 10 10 10 ARGB stored in little endian order. +The 2 bit alpha has 4 values. Here are the comparable 8 bit alpha values. +0 - 0. 00000000b = 0x00 = 0 +1 - 33%. 01010101b = 0x55 = 85 +2 - 66%. 10101010b = 0xaa = 170 +3 - 100%. 11111111b = 0xff = 255 +The 10 bit RGB values range from 0 to 1023. +XR30 is the same as AR30 but with no alpha channel. + +# AB64 and AR64 + +AB64 is similar to ABGR, with 16 bit (2 bytes) per channel. Each channel stores an unsigned short. +In memory R is the lowest and A is the highest. +Each channel has value ranges from 0 to 65535. +AR64 is similar to ARGB. + +# NV12 and NV21 + +NV12 is a biplanar format with a full sized Y plane followed by a single +chroma plane with weaved U and V values. +NV21 is the same but with weaved V and U values. +The 12 in NV12 refers to 12 bits per pixel. NV12 has a half width and half +height chroma channel, and therefore is a 420 subsampling. +NV16 is 16 bits per pixel, with half width and full height. aka 422. +NV24 is 24 bits per pixel with full sized chroma channel. aka 444. +Most NV12 functions allow the destination Y pointer to be NULL. + +# YUY2 and UYVY + +YUY2 is a packed YUV format with half width, full height. + +YUY2 is YUYV in memory +UYVY is UYVY in memory |