/**
 * Generate frame and scan headers that can be prepended to the
 * RTP/JPEG data payload to produce a JPEG compressed image in
 * interchange format.
 *
 * For detailed information, check Appendix A of:
 * https://tools.ietf.org/html/rfc2435
 */ export function makeImageHeader ( ) { return Buffer . from ( [ 0xff , 0xd8 ] ) ; } export function makeQuantHeader ( precision , qTable ) { const lumSize = precision & 1 ? 128 : 64 ; const chmSize = precision & 2 ? 128 : 64 ; if ( qTable . length !== lumSize + chmSize ) { throw new Error ( 'invalid quantization table' ) ; } const lumaPrefix = Buffer . from ( [ 0xff , 0xdb , 0 , lumSize + 3 , 0 ] ) ; const chromaPrefix = Buffer . from ( [ 0xff , 0xdb , 0 , chmSize + 3 , 1 ] ) ; return Buffer . concat ( [ lumaPrefix , qTable . slice ( 0 , lumSize ) , chromaPrefix , qTable . slice ( lumSize ) , ] ) ; } export function makeFrameHeader ( width , height , type ) { return Buffer . from ( [ 0xff , 0xc0 , 0 , 17 , 8 , height >> 8 , height , width >> 8 , width , 3 , 0 , type === 0 ? 0x21 : 0x22 , 0 , 1 , 0x11 , 1 , 2 , 0x11 , 1 , ] ) ; } const LUM_DC_CODELENS = [ 0 , 1 , 5 , 1 , 1 , 1 , 1 , 1 , 1 , 0 , 0 , 0 , 0 , 0 , 0 , 0 ] ; const LUM_DC_SYMBOLS = [ 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ] ; const LUM_AC_CODELENS = [ 0 , 2 , 1 , 3 , 3 , 2 , 4 , 3 , 5 , 5 , 4 , 4 , 0 , 0 , 1 , 0x7d ] ; const LUM_AC_SYMBOLS = [ 0x01 , 0x02 , 0x03 , 0x00 , 0x04 , 0x11 , 0x05 , 0x12 , 0x21 , 0x31 , 0x41 , 0x06 , 0x13 , 0x51 , 0x61 , 0x07 , 0x22 , 0x71 , 0x14 , 0x32 , 0x81 , 0x91 , 0xa1 , 0x08 , 0x23 , 0x42 , 0xb1 , 0xc1 , 0x15 , 0x52 , 0xd1 , 0xf0 , 0x24 , 0x33 , 0x62 , 0x72 , 0x82 , 0x09 , 0x0a , 0x16 , 0x17 , 0x18 , 0x19 , 0x1a , 0x25 , 0x26 , 0x27 , 0x28 , 0x29 , 0x2a , 0x34 , 0x35 , 0x36 , 0x37 , 0x38 , 0x39 , 0x3a , 0x43 , 0x44 , 0x45 , 0x46 , 0x47 , 0x48 , 0x49 , 0x4a , 0x53 , 0x54 , 0x55 , 0x56 , 0x57 , 0x58 , 0x59 , 0x5a , 0x63 , 0x64 , 0x65 , 0x66 , 0x67 , 0x68 , 0x69 , 0x6a , 0x73 , 0x74 , 0x75 , 0x76 , 0x77 , 0x78 , 0x79 , 0x7a , 0x83 , 0x84 , 0x85 , 0x86 , 0x87 , 0x88 , 0x89 , 0x8a , 0x92 , 0x93 , 0x94 , 0x95 , 0x96 , 0x97 , 0x98 , 0x99 , 0x9a , 0xa2 , 0xa3 , 0xa4 , 0xa5 , 0xa6 , 0xa7 , 0xa8 , 0xa9 , 0xaa , 0xb2 , 0xb3 , 0xb4 , 0xb5 , 0xb6 , 0xb7 , 0xb8 , 0xb9 , 0xba , 0xc2 , 0xc3 , 0xc4 , 0xc5 , 0xc6 , 0xc7 , 0xc8 , 0xc9 , 0xca , 0xd2 , 0xd3 , 0xd4 , 0xd5 , 0xd6 , 0xd7 , 0xd8 , 0xd9 , 0xda , 0xe1 , 0xe2 , 0xe3 , 0xe4 , 0xe5 , 0xe6 , 0xe7 , 0xe8 , 0xe9 , 0xea , 0xf1 , 0xf2 , 0xf3 , 0xf4 , 0xf5 , 0xf6 , 0xf7 , 0xf8 , 0xf9 , 0xfa ] ; const CHM_DC_CODELENS = [ 0 , 3 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 0 , 0 , 0 , 0 , 0 ] ; const CHM_DC_SYMBOLS = [ 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ] ; const CHM_AC_CODELENS = [ 0 , 2 , 1 , 2 , 4 , 4 , 3 , 4 , 7 , 5 , 4 , 4 , 0 , 1 , 2 , 0x77 ] ; const CHM_AC_SYMBOLS = [ 0x00 , 0x01 , 0x02 , 0x03 , 0x11 , 0x04 , 0x05 , 0x21 , 0x31 , 0x06 , 0x12 , 0x41 , 0x51 , 0x07 , 0x61 , 0x71 , 0x13 , 0x22 , 0x32 , 0x81 , 0x08 , 0x14 , 0x42 , 0x91 , 0xa1 , 0xb1 , 0xc1 , 0x09 , 0x23 , 0x33 , 0x52 , 0xf0 , 0x15 , 0x62 , 0x72 , 0xd1 , 0x0a , 0x16 , 0x24 , 0x34 , 0xe1 , 0x25 , 0xf1 , 0x17 , 0x18 , 0x19 , 0x1a , 0x26 , 0x27 , 0x28 , 0x29 , 0x2a , 0x35 , 0x36 , 0x37 , 0x38 , 0x39 , 0x3a , 0x43 , 0x44 , 0x45 , 0x46 , 0x47 , 0x48 , 0x49 , 0x4a , 0x53 , 0x54 , 0x55 , 0x56 , 0x57 , 0x58 , 0x59 , 0x5a , 0x63 , 0x64 , 0x65 , 0x66 , 0x67 , 0x68 , 0x69 , 0x6a , 0x73 , 0x74 , 0x75 , 0x76 , 0x77 , 0x78 , 0x79 , 0x7a , 0x82 , 0x83 , 0x84 , 0x85 , 0x86 , 0x87 , 0x88 , 0x89 , 0x8a , 0x92 , 0x93 , 0x94 , 0x95 , 0x96 , 0x97 , 0x98 , 0x99 , 0x9a , 0xa2 , 0xa3 , 0xa4 , 0xa5 , 0xa6 , 0xa7 , 0xa8 , 0xa9 , 0xaa , 0xb2 , 0xb3 , 0xb4 , 0xb5 , 0xb6 , 0xb7 , 0xb8 , 0xb9 , 0xba , 0xc2 , 0xc3 , 0xc4 , 0xc5 , 0xc6 , 0xc7 , 0xc8 , 0xc9 , 0xca , 0xd2 , 0xd3 , 0xd4 , 0xd5 , 0xd6 , 0xd7 , 0xd8 , 0xd9 , 0xda , 0xe2 , 0xe3 , 0xe4 , 0xe5 , 0xe6 , 0xe7 , 0xe8 , 0xe9 , 0xea , 0xf2 , 0xf3 , 0xf4 , 0xf5 , 0xf6 , 0xf7 , 0xf8 , 0xf9 , 0xfa ] ; export function makeHuffmanHeader ( ) { const LUM_DC_BUFFER = [ [ 0xff , 0xc4 , 0 , 3 + LUM_DC_CODELENS . length + LUM_DC_SYMBOLS . length , ( 0 << 4 ) | 0 , ] , LUM_DC_CODELENS , LUM_DC_SYMBOLS , ] ; const LUM_AC_BUFFER = [ [ 0xff , 0xc4 , 0 , 3 + LUM_AC_CODELENS . length + LUM_AC_SYMBOLS . length , ( 1 << 4 ) | 0 , ] , LUM_AC_CODELENS , LUM_AC_SYMBOLS , ] ; const CHM_DC_BUFFER = [ [ 0xff , 0xc4 , 0 , 3 + CHM_DC_CODELENS . length + CHM_DC_SYMBOLS . length , ( 0 << 4 ) | 1 , ] , CHM_DC_CODELENS , CHM_DC_SYMBOLS , ] ; const CHM_AC_BUFFER = [ [ 0xff , 0xc4 , 0 , 3 + CHM_AC_CODELENS . length + CHM_AC_SYMBOLS . length , ( 1 << 4 ) | 1 , ] , CHM_AC_CODELENS , CHM_AC_SYMBOLS , ] ; return Buffer . concat ( [ ... LUM_DC_BUFFER . map ( Buffer . from ) , ... LUM_AC_BUFFER . map ( Buffer . from ) , ... CHM_DC_BUFFER . map ( Buffer . from ) , ... CHM_AC_BUFFER . map ( Buffer . from ) , ] ) ; } export function makeScanHeader ( ) { return Buffer . from ( [ 0xff , 0xda , 0 , 12 , 3 , 0 , 0 , 1 , 0x11 , 2 , 0x11 , 0 , 63 , 0 , ] ) ; } export function makeDRIHeader ( dri ) { return Buffer . from ( [ 0xff , 0xdd , 0x00 , 4 , dri >> 8 , dri & 0xff ] ) ; }