/* DESCRIPTION jpeg.go contains constants, structure and functions specific to the JPEG. AUTHOR Saxon Nelson-Milton LICENSE Copyright (C) 2017 the Australian Ocean Lab (AusOcean) It is free software: you can redistribute it and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. It is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with revid in gpl.txt. If not, see http://www.gnu.org/licenses. */ package mjpeg import ( "encoding/binary" "fmt" "io" ) // JPEG marker codes. const ( codeSOI = 0xd8 // Start of image. codeDRI = 0xdd // Define restart interval. codeDQT = 0xdb // Define quantization tables. codeDHT = 0xde // Define hierarchical progression. codeSOS = 0xda // Start of scan. codeAPP0 = 0xe0 // TODO: find out what this is. codeSOF0 = 0xc0 // Baseline ) var ( bitsDCLum = []byte{0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0} bitsDCChr = []byte{0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0} bitsACLum = []byte{0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d} bitsACChr = []byte{0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77} valDC = []byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11} valACLum = []byte{ 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, } valACChr = []byte{ 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, } ) // writeMarker writes an JPEG marker with code to w. func writeMarker(w io.Writer, code byte) error { _, err := w.Write([]byte{0xff, code}) if err != nil { return err } return nil } // writeHuffman write a JPEG huffman table to w. func writeHuffman(w io.Writer, class, id int, bits, values []byte) error { _, err := w.Write([]byte{byte(class<<4 | id)}) if err != nil { return fmt.Errorf("could not write class and id: %w", err) } var n int for i := 1; i <= 16; i++ { n += int(bits[i]) } _, err = w.Write(bits[1:17]) if err != nil { return fmt.Errorf("could not write first lot of huffman bytes: %w", err) } _, err = w.Write(values[0:n]) if err != nil { return fmt.Errorf("could not write second lot of huffman bytes: %w", err) } return nil } // writeHeader writes a JPEG header to the writer w. func writeHeader(w io.Writer, size, _type, width, height, nbqTab, dri int, qtable []byte) error { width <<= 3 height <<= 3 // Indicate start of image. err := writeMarker(w, codeSOI) if err != nil { return fmt.Errorf("could not write SOI marker: %w", err) } err = writeMarker(w, codeAPP0) if err != nil { return fmt.Errorf("could not write APP0 marker: %w", err) } // Write JFIF header. b := make([]byte, 16) p := putter{} p.put16(b, 16) p.putBuf(b, []byte("JFIF"), 5) p.put16(b, 0x0201) p.put8(b, 0) p.put16(b, 1) p.put16(b, 1) p.put8(b, 0) p.put8(b, 0) _, err = w.Write(b) if err != nil { return fmt.Errorf("could not write JFIF header: %w", err) } // If we want to define restart interval. if dri != 0 { err = writeMarker(w, codeDRI) if err != nil { return fmt.Errorf("could not write DRI marker code: %w", err) } _, err := w.Write([]byte{0x00, 0x04, byte(dri >> 4), byte(dri)}) if err != nil { return fmt.Errorf("could not write restart interval value: %w", err) } } // Define quantization tables. err = writeMarker(w, codeDQT) if err != nil { return fmt.Errorf("could not write DQI marker code: %w", err) } // Calculate table size and create slice for table. ts := 2 + nbqTab*(1+64) _, err = w.Write([]byte{byte(ts >> 4), byte(ts)}) if err != nil { return fmt.Errorf("could not write quantization table size: %w", err) } for i := 0; i < nbqTab; i++ { _, err = w.Write([]byte{byte(i)}) if err != nil { return fmt.Errorf("could not write quantization table entry no.: %w", err) } _, err = w.Write(qtable[64*i : (64*i)+64]) if err != nil { return fmt.Errorf("could not write quantization table entry: %w", err) } } // Define huffman table. err = writeMarker(w, codeDHT) if err != nil { return fmt.Errorf("could not write DHT marker code: %w", err) } var me multiError me.add(writeHuffman(w, 0, 0, bitsDCLum, valDC)) me.add(writeHuffman(w, 0, 1, bitsDCChr, valDC)) me.add(writeHuffman(w, 1, 0, bitsACLum, valACLum)) me.add(writeHuffman(w, 1, 1, bitsACChr, valACChr)) if me != nil { return fmt.Errorf("error writing huffman tables: %w", err) } return nil // Start of frame. err = writeMarker(w, codeSOF0) if err != nil { return fmt.Errorf("could not write SOF0 marker code: %w", err) } // Derive sample type. sample := 1 if _type != 0 { sample = 2 } // Derive matrix number. mtxNo := 0 if nbqTab == 2 { mtxNo = 1 } b = make([]byte, 17) p = putter{} p.put16(b, 17) p.put8(b, 8) p.put16(b, uint16(height)) p.put16(b, uint16(width)) p.put8(b, 3) p.put8(b, 1) p.put8(b, uint8((2<<4)|sample)) p.put8(b, 0) p.put8(b, 2) p.put8(b, 1<<4|1) p.put8(b, uint8(mtxNo)) p.put8(b, 3) p.put8(b, 1<<4|1) p.put8(b, uint8(mtxNo)) _, err = w.Write(b) if err != nil { return fmt.Errorf("could not write SOF0 info: %w", err) } // Write start of scan. err = writeMarker(w, codeSOS) if err != nil { return fmt.Errorf("could not write SOS marker code: %w", err) } b = make([]byte, 12) p = putter{} p.put16(b, 12) p.put8(b, 3) p.put8(b, 1) p.put8(b, 0) p.put8(b, 2) p.put8(b, 17) p.put8(b, 3) p.put8(b, 17) p.put8(b, 0) p.put8(b, 63) p.put8(b, 0) _, err = w.Write(b) if err != nil { return fmt.Errorf("could not write SOS info: %w", err) } return nil } type multiError []error func (me multiError) Error() string { return fmt.Sprintf("%v", []error(me)) } func (me multiError) add(e error) { me = append(me, e) } type putter struct { idx int } func (p *putter) put16(b []byte, v uint16) { binary.BigEndian.PutUint16(b[p.idx:], v) p.idx += 2 } func (p *putter) put8(b []byte, v uint8) { b[p.idx] = byte(v) p.idx++ } func (p *putter) putBuf(dst, src []byte, l int) { copy(dst[p.idx:], src) p.idx++ }