container/mts: wrote test for BytesForPTSInterval and corrected bugs

container/mts/payload.go

@@ -119,6 +119,13 @@ func (c *Clip) Bytes() []byte {
 	return c.backing
 }
 
+// Errors used in BytesForPTSInterval.
+var (
+	errBadLowerBound   = errors.New("'from' cannot be found")
+	errBadUpperBound   = errors.New("'to' cannot be found")
+	errInvalidPTSRange = errors.New("PTS interval invalid")
+)
+
 // BytesForPTSInterval returns the media data between PTS' from and to. If from
 // sits between two PTS, the Frame posessing lower PTS will be considered the start.
 // The Frame before the Frame corresponding to to will be considered the final
@@ -126,22 +133,22 @@ func (c *Clip) Bytes() []byte {
 func (c *Clip) BytesForPTSInterval(from, to uint64) ([]byte, error) {
 	// First check that the interval makes sense.
 	if from >= to {
-		return nil, errors.New("PTS interval is invalid")
+		return nil, errInvalidPTSRange
 	}
 
 	// Use binary search to find 'from'.
-	n := len(c.frames)
+	n := len(c.frames) - 1
 	idx := sort.Search(
 		n,
 		func(i int) bool {
-			if from >= c.frames[i].PTS && from < c.frames[i].PTS {
+			if from < c.frames[i+1].PTS {
 				return true
 			}
 			return false
 		},
 	)
 	if idx == n {
-		return nil, errors.New("'from' cannot be found")
+		return nil, errBadLowerBound
 	}
 
 	// Now get the start index for the backing slice from this Frame.
@@ -153,18 +160,18 @@ func (c *Clip) BytesForPTSInterval(from, to uint64) ([]byte, error) {
 	idx = sort.Search(
 		n,
 		func(i int) bool {
-			if to >= c.frames[i+off].PTS && from < c.frames[i+off].PTS {
+			if to <= c.frames[i+off].PTS {
 				return true
 			}
 			return false
 		},
 	)
 	if idx == n {
-		return nil, errors.New("'to' cannot be found")
+		return nil, errBadUpperBound
 	}
 
 	// Now get the end index for the backing slice from this Frame, and return
 	// segment from backing slice corresponding to start and end.
-	end := c.frames[idx+off].idx
+	end := c.frames[idx+off-1].idx
-	return c.backing[start:end], nil
+	return c.backing[start : end+len(c.frames[idx+off].Media)], nil
 }

container/mts/payload_test.go

@@ -85,8 +85,25 @@ func TestExtract(t *testing.T) {
 
 	// Check frames individually.
 	for i, frame := range want.frames {
-		if !reflect.DeepEqual(frame, got.frames[i]) {
+		// Check media data.
-			t.Fatalf("did not get expected result.\nGot: %v\n, Want: %v\n", got.frames[i], frame)
+		wantMedia := frame.Media
+		gotMedia := got.frames[i].Media
+		if !bytes.Equal(wantMedia, gotMedia) {
+			t.Fatalf("did not get expected data for frame: %v\nGot: %v\nWant: %v\n", i, gotMedia, wantMedia)
+		}
+
+		// Check stream ID.
+		wantID := frame.ID
+		gotID := got.frames[i].ID
+		if wantID != gotID {
+			t.Fatalf("did not get expected ID for frame: %v\nGot: %v\nWant: %v\n", i, gotID, wantID)
+		}
+
+		// Check meta.
+		wantMeta := frame.Meta
+		gotMeta := got.frames[i].Meta
+		if !reflect.DeepEqual(wantMeta, gotMeta) {
+			t.Fatalf("did not get expected meta for frame: %v\nGot: %v\nwant: %v\n", i, gotMeta, wantMeta)
 		}
 	}
 }
@@ -207,3 +224,94 @@ func genFrames(n, min, max int) [][]byte {
 	}
 	return frames
 }
+
+// TestBytesForPTSInterval checks that BytesForPTSInterval can correctly return
+// a slice of media data corresponding to a given PTS interval.
+func TestBytesForPTSInterval(t *testing.T) {
+	const (
+		numOfTestFrames = 10
+		ptsInterval     = 4
+		frameSize       = 3
+	)
+
+	clip := &Clip{}
+
+	// Generate test frames.
+	for i := 0; i < numOfTestFrames; i++ {
+		clip.backing = append(clip.backing, []byte{byte(i), byte(i), byte(i)}...)
+		clip.frames = append(
+			clip.frames,
+			Frame{
+				Media: clip.backing[i*frameSize : (i+1)*frameSize],
+				PTS:   uint64(i * ptsInterval),
+				idx:   i * frameSize,
+			},
+		)
+	}
+
+	// We test each of these scenarios.
+	tests := []struct {
+		from   uint64
+		to     uint64
+		expect []byte
+		err    error
+	}{
+		{
+			from: 6,
+			to:   15,
+			expect: []byte{
+				0x01, 0x01, 0x01,
+				0x02, 0x02, 0x02,
+				0x03, 0x03, 0x03,
+			},
+			err: nil,
+		},
+		{
+			from: 4,
+			to:   16,
+			expect: []byte{
+				0x01, 0x01, 0x01,
+				0x02, 0x02, 0x02,
+				0x03, 0x03, 0x03,
+			},
+			err: nil,
+		},
+		{
+			from:   10,
+			to:     5,
+			expect: nil,
+			err:    errInvalidPTSRange,
+		},
+		{
+			from:   50,
+			to:     70,
+			expect: nil,
+			err:    errBadLowerBound,
+		},
+		{
+			from:   5,
+			to:     70,
+			expect: nil,
+			err:    errBadUpperBound,
+		},
+	}
+
+	// Run tests.
+	for i, test := range tests {
+		got, err := clip.BytesForPTSInterval(test.from, test.to)
+
+		// First check the error.
+		if err != nil && err != test.err {
+			t.Errorf("unexpected error: %v for test: %v from BytesForPTSInterval", err, i)
+			continue
+		} else if err != test.err {
+			t.Errorf("expected to get error: %v for test: %v from BytesForPTSInterval", test.err, i)
+			continue
+		}
+
+		// Now check data.
+		if test.err == nil && !bytes.Equal(test.expect, got) {
+			t.Errorf("did not get expected data for test: %v from BytesForPTSInterval.\n Got: %v\n, Want: %v\n", i, got, test.expect)
+		}
+	}
+}