codec/mjpeg/jpeg.go: added writeHeader function to write JPEG header

This also included the addition of some lunimance and chrominance tables, a multiError type (implements error) and a putter type, that will put uint16s, bytes and "buffers" into a byte
slice.

codec/mjpeg/jpeg.go

@@ -25,19 +25,75 @@ LICENSE
 package mjpeg
 
 import (
+	"encoding/binary"
 	"fmt"
 	"io"
 )
 
 // JPEG marker codes.
 const (
-	soi  = 0xd8 // Start of image.
+	codeSOI  = 0xd8 // Start of image.
-	dri  = 0xdd // Define restart interval.
+	codeDRI  = 0xdd // Define restart interval.
-	dqt  = 0xdb // Define quantization tables.
+	codeDQT  = 0xdb // Define quantization tables.
-	dht  = 0xde // Define hierarchical progression.
+	codeDHT  = 0xde // Define hierarchical progression.
-	sos  = 0xda // Start of scan.
+	codeSOS  = 0xda // Start of scan.
-	app0 = 0xe0 // TODO: find out what this is.
+	codeAPP0 = 0xe0 // TODO: find out what this is.
-	sof0 = 0xc0 // Baseline
+	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.
@@ -73,3 +129,184 @@ func writeHuffman(w io.Writer, class, id int, bits, values []byte) error {
 
 	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++
+}