flac: Add preliminary encoding support.

Support for encoding metadata has been added.

Proper support for encoding audio samples is yet to be
implemented. For now, simply copy the original encoded
audio data from the source FLAC file.

The API mirrors that of image.Encode.

Updates #14.

internal/bits/reader.go

@@ -1,4 +1,4 @@
-// Package bits provides bit reading operations and binary decoding algorithms.
+// Package bits provides bit access operations and binary decoding algorithms.
 package bits
 
 import (
@@ -20,7 +20,7 @@ type Reader struct {
 }
 
 // NewReader returns a new Reader that reads bits from r.
-func NewReader(r io.Reader) (br *Reader) {
+func NewReader(r io.Reader) *Reader {
 	return &Reader{r: r}
 }
 

meta/cuesheet.go

@@ -26,7 +26,7 @@ type CueSheet struct {
 	Tracks []CueSheetTrack
 }
 
-// parseCueSheet reads and parses the body of an CueSheet metadata block.
+// parseCueSheet reads and parses the body of a CueSheet metadata block.
 func (block *Block) parseCueSheet() error {
 	// Parse cue sheet.
 	// 128 bytes: MCN.

meta/meta.go

@@ -172,13 +172,13 @@ type Type uint8
 
 // Metadata block body types.
 const (
-	TypeStreamInfo Type = iota
-	TypePadding
-	TypeApplication
-	TypeSeekTable
-	TypeVorbisComment
-	TypeCueSheet
-	TypePicture
+	TypeStreamInfo    Type = 0
+	TypePadding       Type = 1
+	TypeApplication   Type = 2
+	TypeSeekTable     Type = 3
+	TypeVorbisComment Type = 4
+	TypeCueSheet      Type = 5
+	TypePicture       Type = 6
 )
 
 func (t Type) String() string {

meta/picture.go

@@ -50,7 +50,7 @@ type Picture struct {
 	Data []byte
 }
 
-// parsePicture reads and parses the body of an Picture metadata block.
+// parsePicture reads and parses the body of a Picture metadata block.
 func (block *Block) parsePicture() error {
 	// 32 bits: Type.
 	pic := new(Picture)

meta/seektable.go

@@ -14,7 +14,7 @@ type SeekTable struct {
 	Points []SeekPoint
 }
 
-// parseSeekTable reads and parses the body of an SeekTable metadata block.
+// parseSeekTable reads and parses the body of a SeekTable metadata block.
 func (block *Block) parseSeekTable() error {
 	// The number of seek points is derived from the header length, divided by
 	// the size of a SeekPoint; which is 18 bytes.

meta/streaminfo.go

@@ -39,7 +39,7 @@ type StreamInfo struct {
 	MD5sum [md5.Size]uint8
 }
 
-// parseStreamInfo reads and parses the body of an StreamInfo metadata block.
+// parseStreamInfo reads and parses the body of a StreamInfo metadata block.
 func (block *Block) parseStreamInfo() error {
 	// 16 bits: BlockSizeMin.
 	br := bits.NewReader(block.lr)

meta/vorbiscomment.go

@@ -16,7 +16,7 @@ type VorbisComment struct {
 	Tags [][2]string
 }
 
-// parseVorbisComment reads and parses the body of an VorbisComment metadata
+// parseVorbisComment reads and parses the body of a VorbisComment metadata
 // block.
 func (block *Block) parseVorbisComment() error {
 	// 32 bits: vendor length.