codec/mjpeg/lex & lex_test.go: modified Lex to work with thumbnailed JPEG images and fixed Lex tests.

codec/mjpeg/lex.go

@@ -3,10 +3,12 @@ NAME
   lex.go
 
 DESCRIPTION
-  lex.go provides a lexer to extract separate JPEG images from a MJPEG stream.
+  lex.go provides a lexer to extract separate JPEG images from a JPEG stream.
+  This could either be a series of descrete JPEG images, or an MJPEG stream.
 
 AUTHOR
   Dan Kortschak <dan@ausocean.org>
+  Saxon Nelson-Milton <saxon@ausocean.org>
 
 LICENSE
   lex.go is Copyright (C) 2017 the Australian Ocean Lab (AusOcean)
@@ -25,8 +27,6 @@ LICENSE
   along with revid in gpl.txt. If not, see http://www.gnu.org/licenses.
 */
 
-// lex.go provides a lexer to extract separate JPEG images from a MJPEG stream.
-
 package mjpeg
 
 import (
@@ -35,15 +35,19 @@ import (
 	"fmt"
 	"io"
 	"time"
+
+	"bitbucket.org/ausocean/utils/logger"
 )
 
+var Log logger.LoggerIF
+
 var noDelay = make(chan time.Time)
 
 func init() {
 	close(noDelay)
 }
 
-// Lex parses MJPEG frames read from src into separate writes to dst with
+// Lex parses JPEG frames read from src into separate writes to dst with
 // successive writes being performed not earlier than the specified delay.
 func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 	var tick <-chan time.Time
@@ -65,9 +69,13 @@ func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 		if err != nil {
 			return err
 		}
+
 		if !bytes.Equal(buf, []byte{0xff, 0xd8}) {
-			return fmt.Errorf("parser: not MJPEG frame start: %#v", buf)
+			return fmt.Errorf("parser: not JPEG frame start: %#v", buf)
 		}
+
+		nImg := 1
+
 		var last byte
 		for {
 			b, err := r.ReadByte()
@@ -77,16 +85,28 @@ func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 				}
 				return err
 			}
+
 			buf = append(buf, b)
+
+			if last == 0xff && b == 0xd8 {
+				nImg++
+			}
+
 			if last == 0xff && b == 0xd9 {
+				nImg--
+			}
+
+			if nImg == 0 {
+				<-tick
+				Log.Debug("writing buf","len(buf)",len(buf))
+				_, err = dst.Write(buf)
+				if err != nil {
+					return err
+				}
 				break
 			}
+
 			last = b
 		}
-		<-tick
-		_, err = dst.Write(buf)
-		if err != nil {
-			return err
-		}
 	}
 }

codec/mjpeg/lex_test.go

@@ -30,10 +30,17 @@ LICENSE
 package mjpeg
 
 import (
+	"bytes"
+	"fmt"
+	"io"
+	"reflect"
+	"testing"
 	"time"
+
+	"bitbucket.org/ausocean/utils/logger"
 )
 
-var mjpegTests = []struct {
+var jpegTests = []struct {
 	name  string
 	input []byte
 	delay time.Duration
@@ -42,18 +49,21 @@ var mjpegTests = []struct {
 }{
 	{
 		name: "empty",
+		err:  io.ErrUnexpectedEOF,
 	},
 	{
 		name:  "null",
 		input: []byte{0xff, 0xd8, 0xff, 0xd9},
 		delay: 0,
 		want:  [][]byte{{0xff, 0xd8, 0xff, 0xd9}},
+		err:  io.ErrUnexpectedEOF,
 	},
 	{
 		name:  "null delayed",
 		input: []byte{0xff, 0xd8, 0xff, 0xd9},
 		delay: time.Millisecond,
 		want:  [][]byte{{0xff, 0xd8, 0xff, 0xd9}},
+		err:  io.ErrUnexpectedEOF,
 	},
 	{
 		name: "full",
@@ -72,6 +82,7 @@ var mjpegTests = []struct {
 			{0xff, 0xd8, 'l', 'e', 'n', 'g', 't', 'h', 0xff, 0xd9},
 			{0xff, 0xd8, 's', 'p', 'r', 'e', 'a', 'd', 0xff, 0xd9},
 		},
+		err:  io.ErrUnexpectedEOF,
 	},
 	{
 		name: "full delayed",
@@ -90,15 +101,15 @@ var mjpegTests = []struct {
 			{0xff, 0xd8, 'l', 'e', 'n', 'g', 't', 'h', 0xff, 0xd9},
 			{0xff, 0xd8, 's', 'p', 'r', 'e', 'a', 'd', 0xff, 0xd9},
 		},
+		err:  io.ErrUnexpectedEOF,
 	},
 }
 
-// FIXME this needs to be adapted
+func TestLex(t *testing.T) {
-/*
+	Log = (*logger.TestLogger)(t)
-func Lex(t *testing.T) {
+	for _, test := range jpegTests {
-	for _, test := range mjpegTests {
 		var buf chunkEncoder
-		err := MJPEG(&buf, bytes.NewReader(test.input), test.delay)
+		err := Lex(&buf, bytes.NewReader(test.input), test.delay)
 		if fmt.Sprint(err) != fmt.Sprint(test.err) {
 			t.Errorf("unexpected error for %q: got:%v want:%v", test.name, err, test.err)
 		}
@@ -111,4 +122,12 @@ func Lex(t *testing.T) {
 		}
 	}
 }
-*/
+
+type chunkEncoder [][]byte
+
+func (e *chunkEncoder) Write(b []byte) (int, error) {
+	*e = append(*e, b)
+	return len(b), nil
+}
+
+func (*chunkEncoder) Stream() <-chan []byte { panic("INVALID USE") }

go.mod

@@ -4,7 +4,7 @@ go 1.13
 
 require (
 	bitbucket.org/ausocean/iot v1.3.0
-	bitbucket.org/ausocean/utils v1.2.15
+	bitbucket.org/ausocean/utils v1.2.17
 	github.com/Comcast/gots v0.0.0-20190305015453-8d56e473f0f7
 	github.com/go-audio/audio v0.0.0-20181013203223-7b2a6ca21480
 	github.com/go-audio/wav v0.0.0-20181013172942-de841e69b884

go.sum

@@ -6,6 +6,8 @@ bitbucket.org/ausocean/utils v1.2.14 h1:v5eBYavkEqKOBCppR6P451eT9UT/CQReMsOZZBUP
 bitbucket.org/ausocean/utils v1.2.14/go.mod h1:uXzX9z3PLemyURTMWRhVI8uLhPX4uuvaaO85v2hcob8=
 bitbucket.org/ausocean/utils v1.2.15 h1:Pz99ZfobdhACTtU6oj9BTyBcNSQulLvPT7wq4P343Es=
 bitbucket.org/ausocean/utils v1.2.15/go.mod h1:uXzX9z3PLemyURTMWRhVI8uLhPX4uuvaaO85v2hcob8=
+bitbucket.org/ausocean/utils v1.2.17 h1:6ZqXvxRXHHL18s2kn22E2/AORNn2WsgQXcEnctWwvrk=
+bitbucket.org/ausocean/utils v1.2.17/go.mod h1:uoIRyy4jwH0/9b/t9tfPuV9Vl14AONeILw9KimUISYg=
 github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/Comcast/gots v0.0.0-20190305015453-8d56e473f0f7 h1:LdOc9B9Bj6LEsKiXShkLA3/kpxXb6LJpH+ekU2krbzw=