container/mts: BytesForMetaInterval renamed to TrimToMetaRange and now returns Clip for similar reasons to previous commit

container/mts/payload.go

@@ -192,9 +192,9 @@ var (
 	errMetaUpperBound = errors.New("meta 'to' cannot be found")
 )
 
-// BytesForMetaInterval will return the media data as a slice between two meta
-// values 'from' and 'to', of key 'key'. The meta values must not be the same.
-func (c *Clip) BytesForMetaInterval(key, from, to string) ([]byte, error) {
+// TrimToMetaRange returns a sub Clip with meta range described by from and to
+// with key 'key'. The meta values must not be equivalent.
+func (c *Clip) TrimToMetaRange(key, from, to string) (*Clip, error) {
 	// First check that the interval makes sense.
 	if from == to {
 		return nil, errMetaRange
@@ -205,6 +205,7 @@ func (c *Clip) BytesForMetaInterval(key, from, to string) ([]byte, error) {
 	// Try and find from.
 	for i := 0; i < len(c.frames); i++ {
 		f := c.frames[i]
+		startFrameIdx := i
 		if f.Meta[key] == from {
 			start = f.idx
 
@@ -213,7 +214,11 @@ func (c *Clip) BytesForMetaInterval(key, from, to string) ([]byte, error) {
 				f = c.frames[i]
 				if f.Meta[key] == to {
 					end = f.idx
-					return c.backing[start : end+len(f.Media)], nil
+					endFrameIdx := i
+					return &Clip{
+						frames:  c.frames[startFrameIdx : endFrameIdx+1],
+						backing: c.backing[start : end+len(f.Media)],
+					}, nil
 				}
 			}
 			return nil, errMetaUpperBound

container/mts/payload_test.go

@@ -316,9 +316,9 @@ func TestTrimToPTSRange(t *testing.T) {
 	}
 }
 
-// TestBytesForMetaInterval checks that we can correctly get media data between
-// two meta values using BytesForMetaInterval.
-func TestBytesForMetaInterval(t *testing.T) {
+// TestTrimToMetaRange checks that Clip.TrimToMetaRange correctly provides a
+// sub Clip for a given meta range.
+func TestTrimToMetaRange(t *testing.T) {
 	const (
 		numOfTestFrames = 10
 		ptsInterval     = 4
@@ -382,7 +382,7 @@ func TestBytesForMetaInterval(t *testing.T) {
 
 	// Run tests.
 	for i, test := range tests {
-		got, err := clip.BytesForMetaInterval(key, test.from, test.to)
+		got, err := clip.TrimToMetaRange(key, test.from, test.to)
 
 		// First check the error.
 		if err != nil && err != test.err {
@@ -394,7 +394,7 @@ func TestBytesForMetaInterval(t *testing.T) {
 		}
 
 		// Now check data.
-		if test.err == nil && !bytes.Equal(test.expect, got) {
+		if test.err == nil && !bytes.Equal(test.expect, got.Bytes()) {
 			t.Errorf("did not get expected data for test: %v\n Got: %v\n, Want: %v\n", i, got, test.expect)
 		}
 	}