mp3: Only look for supported mp3 sync headers

wader · Sep 12, 2021 · 4344b62 · 4344b62
1 parent da386ea
commit 4344b62
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Showing 4 changed files with 11 additions and 9 deletions.
diff --git a/format/mp3/mp3.go b/format/mp3/mp3.go
@@ -48,9 +48,11 @@ func mp3Decode(d *decode.D, in interface{}) interface{} {
 	d.FieldArrayFn("frames", func(d *decode.D) {
 		for d.NotEnd() {
 			startFindSync := d.Pos()
-			syncLen, _, err := d.TryPeekFind(16, 8, func(v uint64) bool {
-				return v&0b1111_1111_1110_0000 == 0b1111_1111_1110_0000
-			}, d.BitsLeft())
+			syncLen, _, err := d.TryPeekFind(16, 8, -1, func(v uint64) bool {
+				return (v&0b1111_1111_1110_0000 == 0b1111_1111_1110_0000 && // sync header
+					v&0b0000_0000_0001_1000 != 0b0000_0000_0000_1000 && // not reserved mpeg version
+					v&0b0000_0000_0000_0110 == 0b0000_0000_0000_0010) // layer 3
+			})
 			if err != nil {
 				break
 			}

diff --git a/format/mpeg/annexb.go b/format/mpeg/annexb.go
@@ -5,9 +5,9 @@ import (
 )
 
 func annexBFindStartCode(d *decode.D) (int64, int64, error) {
-	offset, v, err := d.TryPeekFind(32, 8, func(v uint64) bool {
+	offset, v, err := d.TryPeekFind(32, 8, -1, func(v uint64) bool {
 		return annexBDecodeStartCodeLen(v) > 0
-	}, d.BitsLeft())
+	})
 	return offset, annexBDecodeStartCodeLen(v), err
 }
 

diff --git a/pkg/decode/decode.go b/pkg/decode/decode.go
@@ -292,7 +292,7 @@ func (d *D) PeekBytes(nBytes int) []byte {
 }
 
 func (d *D) PeekFind(nBits int, seekBits int64, fn func(v uint64) bool, maxLen int64) (int64, uint64) {
-	peekBits, v, err := d.TryPeekFind(nBits, seekBits, fn, maxLen)
+	peekBits, v, err := d.TryPeekFind(nBits, seekBits, maxLen, fn)
 	if err != nil {
 		panic(IOError{Err: err, Op: "PeekFind", Size: 0, Pos: d.Pos()})
 	}
@@ -313,9 +313,9 @@ func (d *D) TryHasBytes(hb []byte) bool {
 
 // PeekFindByte number of bytes to next v
 func (d *D) PeekFindByte(findV uint8, maxLen int64) int64 {
-	peekBits, _, err := d.TryPeekFind(8, 8, func(v uint64) bool {
+	peekBits, _, err := d.TryPeekFind(8, 8, maxLen*8, func(v uint64) bool {
 		return uint64(findV) == v
-	}, maxLen*8)
+	})
 	if err != nil {
 		panic(IOError{Err: err, Op: "PeekFindByte", Size: 0, Pos: d.Pos()})
 

diff --git a/pkg/decode/decode_readers.go b/pkg/decode/decode_readers.go
@@ -94,7 +94,7 @@ func (d *D) Bits(nBits int) (uint64, error) {
 	return n, nil
 }
 
-func (d *D) TryPeekFind(nBits int, seekBits int64, fn func(v uint64) bool, maxLen int64) (int64, uint64, error) {
+func (d *D) TryPeekFind(nBits int, seekBits int64, maxLen int64, fn func(v uint64) bool) (int64, uint64, error) {
 	start, err := d.bitBuf.SeekBits(0, io.SeekCurrent)
 	if err != nil {
 		return 0, 0, err