MPEG.txt (3254B)
1 From: Wilson Woo <wilson00@HK.Super.NET> 2 To: submit@wotsit.demon.co.uk 3 Subject: MPEG Video 4 5 THIS TEXT CONTAINS ONLY MPEG VIDEO HEADER INFO - BY WILSON WOO 6 It's only what I know. Please feel free to update it. 7 8 Below is information got from someone. 9 10 /*****************************************************************/ 11 12 Sequence Header 13 14 This contains information related to one or more "group-of-pictures" 15 16 Byte# Data Details 17 =================================================================== 18 1-4 Sequence header In Hex 000001B3 19 code 20 12 bits Horizontal size In pixels 21 12 bits Vertical size In pixels 22 4 bits Pel aspect ratio See below 23 28-4+12 24 18 bits Picture rate See below 25 1 bit Marker bit Always 1 26 10 bits VBV buffer size Minimum buffer needed to decode this 27 sequence of pictures; in 16KB units 28 1 bit Constrained 29 parameter flag 30 1 bit Load intra 0: false; 1: true (matrix follows) 31 quantizer matrix 32 64 bytes Intra quantizer Optional 33 matrix 34 1 bit Load nonintra 0: false; 1: true (matrix follows) 35 quantizer matrix 36 64 bytes Nonintra quantizer Optional 37 matrix 38 - Squence extension Optional 39 Data 40 - User data Optional application-dependent data 41 =================================================================== 42 43 Aspect raios are defined by a code which represents the height and 44 width of the Video image. 45 Picture rates are also defined by a code that represents the number 46 of pictures that may be displayed each second. 47 48 Each group of pictures has a header that contains one "I picture" 49 and zero or more B and P pictures. The header is concerned with 50 the time synchronisation for the first picture in this group, and 51 the closeness of the previous group to this one. 52 53 /*****************************************************************/ 54 55 For picture rate: 56 1 = 23.976 frames/sec 57 2 = 24 58 3 = 25 59 4 = 29.97 60 5 = 30 61 6 = 50 62 7 = 59.94 63 8 = 60 64 65 Here gives an example. Below is Hex dump of first 256 bytes of 66 the first Video frame of TEST.MPG from XingMPEG. 67 68 00 00 01 B3 16 00 F0 C4 02 A3 20 A5 10 12 12 14 69 14 14 16 16 16 16 18 18 19 18 18 1A 1B 1B 1B 1B 70 1A 1C 1D 1E 1E 1E 1D 1C 1E 1F 20 21 21 20 1F 1E 71 21 23 23 24 23 23 21 25 26 27 27 26 25 29 2A 2A 72 2A 29 2D 2D 2D 2D 30 31 30 34 34 38 16 00 F0 C4 73 00 00 01 B8 00 08 00 00 00 00 01 00 00 0A 72 00 74 00 00 01 01 13 F9 50 02 BC B2 B8 BE 68 8B A4 9F 75 C5 B5 CA 00 56 76 39 65 F2 30 8B A6 9D 50 69 E7 76 DA FE 13 CF B7 FF 8F F4 CE 7B FA 0E F0 66 AE 1C 77 5D E7 00 C8 0A 92 B9 29 3C 21 23 F1 D6 40 13 06 78 F0 10 10 C6 27 80 A0 34 E1 C8 E4 0F 74 91 DA C4 79 03 A0 DC 03 12 60 18 49 27 1D D4 BC 67 0E 54 8C 80 96 FC 5D C0 06 E0 1A 72 11 7C 9A 8D C9 45 89 6D 81 CD C4 0B 63 DC 90 18 24 00 EC 84 90 18 10 C9 3B 82 1E A7 60 3C 9D 74 80 76 05 0B 02 81 A9 29 39 68 83 53 8F 59 F1 BF 93 FB A0 04 01 BC B0 CE 18 E1 25 84 85 Sequence header = (Hex) 00 00 01 B3 86 Horizontal size = 0x160 = 352 87 Vertical size = 0x0F0 = 240 88 Pel aspect ratio = [I don't know] 89 Picture rate = 4 = 29.97 frames/sec 90 Marker bit = 1