In oggtag.go a struct named OggFIle was created, ReadFile turned into a constructor NewOggFile. And GetTag and GetDuration turned into methods.
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D22A817D95815393
@ -56,7 +56,7 @@ func (dj *DJHandlers) PlaylistNext(w http.ResponseWriter, _ *http.Request) {
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log.Println("the end of a playlist has been reached")
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} else {
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go func() {
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bs, be, err := oggtag.ReadFile(nxt)
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oggf, err := oggtag.NewOggFile(nxt)
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if err != nil {
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log.Println("cannot read an OGG file", nxt, ":", err)
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http.Error(w, "cannot read an OGG file", http.StatusInternalServerError)
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@ -64,9 +64,9 @@ func (dj *DJHandlers) PlaylistNext(w http.ResponseWriter, _ *http.Request) {
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}
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song := radio.Song{
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Artist: oggtag.GetTag(bs, "artist"),
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Title: oggtag.GetTag(bs, "title"),
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Duration: oggtag.GetDuration(bs, be),
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Artist: oggf.GetTag("artist"),
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Title: oggf.GetTag("title"),
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Duration: oggf.GetDuration(),
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MaxListeners: dj.listeners.Current(),
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StartAt: time.Now()}
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radio.CheckAndUpdateMostListenedSong(dj.songList.Current())
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@ -12,85 +12,89 @@ import (
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"time"
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)
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const bufferLength = 4096
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const MagicSequence = "OggS"
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const MagicSequenceLen = len(MagicSequence)
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const VorbisSequence = "vorbis"
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const VorbisSequenceLen = len(VorbisSequence)
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const (
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bufferLength = 6144
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OggS = "OggS"
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OggSLen = len(OggS)
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Vorbis = "vorbis"
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VorbisLen = len(Vorbis)
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)
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// OggReadFile returns a head of an OGG file, and a buffer contains last frame.
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func ReadFile(path string) (buf_start, buf_end []byte, _ error) {
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// OggFile holds a head of a file and a tail part conatining last granule.
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type OggFile struct {
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bufHead, bufTail []byte
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}
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// NewOggFile reads a file and returns a new OggFile.
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func NewOggFile(path string) (*OggFile, error) {
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f, err := os.Open(path)
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if err != nil {
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return nil, nil, err
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return nil, err
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}
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defer f.Close()
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of := &OggFile{}
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of.bufHead = make([]byte, bufferLength)
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if _, err := f.Read(of.bufHead); err != nil {
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return nil, err
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}
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buf_start = make([]byte, bufferLength)
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if _, err := f.Read(buf_start); err != nil {
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return nil, nil, err
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}
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buf_end = make([]byte, bufferLength)
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of.bufTail = make([]byte, bufferLength)
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if _, err := f.Seek(-bufferLength, io.SeekEnd); err != nil {
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return nil, nil, err
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return nil, err
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}
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fst, err := f.Stat()
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if err != nil {
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return nil, nil, err
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return nil, err
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}
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for offset := int64(bufferLength); offset <= fst.Size(); offset += bufferLength {
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if _, err := f.Seek(-offset, io.SeekEnd); err != nil {
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return nil, nil, err
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return nil, err
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}
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if _, err := f.Read(buf_end); err != nil {
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return nil, nil, err
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if _, err := f.Read(of.bufTail); err != nil {
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return nil, err
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}
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if bytes.Contains(buf_end, []byte(MagicSequence)) {
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if bytes.Contains(of.bufTail, []byte(OggS)) {
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break
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}
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}
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return
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return of, nil
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}
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// OggGetTag is searching for a certain tag in a given buffer buf and returns
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// its value.
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//
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// It is a simple implementation that doesn't parse a header and instead just
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// looking for a certain tag preceded with three zero bytes and ends with
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// an = character.
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func GetTag(buf []byte, tag string) string {
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tagIdx := bytes.Index(buf, append([]byte{0, 0, 0}, (tag+"=")...))
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// GetTag is searching for a certain tag and returns its value or an empty string.
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func (of *OggFile) GetTag(tag string) string {
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tagIdx := bytes.Index(of.bufHead, append([]byte{0, 0, 0}, (tag+"=")...))
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if tagIdx == -1 {
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tagIdx = bytes.Index(buf, append([]byte{0, 0, 0}, (strings.ToUpper(tag)+"=")...))
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if tagIdx == -1 {
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if tagIdx = bytes.Index(of.bufHead, append([]byte{0, 0, 0}, (strings.ToUpper(tag)+"=")...)); tagIdx == -1 {
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return ""
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}
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}
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tagIdx += 3
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tagNameLen := len(tag) + 1
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valStart := tagIdx + tagNameLen
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valLen := int(buf[tagIdx-4]) - tagNameLen
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return string(buf[valStart : valStart+valLen])
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valLen := int(of.bufHead[tagIdx-4]) - tagNameLen
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return string(of.bufHead[valStart : valStart+valLen])
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}
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// OggGetDuration returns song's duration in milliseconds.
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func GetDuration(buf_start, buf_end []byte) time.Duration {
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rateIdx := bytes.Index(buf_start, []byte(VorbisSequence)) +
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VorbisSequenceLen + 5
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rateBytes := buf_start[rateIdx : rateIdx+4]
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// GetDuration returns song's duration in milliseconds.
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func (of *OggFile) GetDuration() time.Duration {
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rateIdx := bytes.Index(of.bufHead, []byte(Vorbis)) +
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VorbisLen + 5
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rateBytes := of.bufHead[rateIdx : rateIdx+4]
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rate := int32(rateBytes[0]) + int32(rateBytes[1])<<8 +
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int32(rateBytes[2])<<16 + int32(rateBytes[3])<<24
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granuleIdx := bytes.LastIndex(buf_end, []byte(MagicSequence)) +
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MagicSequenceLen + 2
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granuleBytes := buf_end[granuleIdx : granuleIdx+8]
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granuleIdx := bytes.LastIndex(of.bufTail, []byte(OggS)) +
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OggSLen + 2
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granuleBytes := of.bufTail[granuleIdx : granuleIdx+8]
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granule := int64(granuleBytes[0]) + int64(granuleBytes[1])<<8 +
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int64(granuleBytes[2])<<16 + int64(granuleBytes[3])<<24 +
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int64(granuleBytes[4])<<32 + int64(granuleBytes[5])<<40 +
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@ -1,66 +1,57 @@
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package oggtag
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import (
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"bytes"
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"os"
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"testing"
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"time"
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)
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const bufferSize = 4096
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const sampleSong = "/mnt/data/appdata/radio/fallback.ogg"
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const sampleArtist = "breskina"
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const sampleTitle = "Песня про мечты"
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func TestGetTag(t *testing.T) {
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f, _ := os.Open(sampleSong)
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buf := make([]byte, bufferSize)
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f.Read(buf)
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tag := GetTag(buf, "artist")
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oggf, err := NewOggFile(sampleSong)
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if err != nil {
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t.Fatal(err)
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}
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tag := oggf.GetTag("artist")
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if tag != sampleArtist {
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t.Error(tag, "!=", sampleArtist)
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}
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tag = GetTag(buf, "title")
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tag = oggf.GetTag("title")
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if tag != sampleTitle {
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t.Error(tag, "!=", sampleTitle)
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}
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}
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func BenchmarkGetTag(b *testing.B) {
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f, _ := os.Open(sampleSong)
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buf := make([]byte, bufferSize)
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f.Read(buf)
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oggf, err := NewOggFile(sampleSong)
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if err != nil {
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b.Fatal(err)
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}
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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GetTag(buf, "artist")
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oggf.GetTag("artist")
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}
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}
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func TestReadFile(t *testing.T) {
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bs, bf, err := ReadFile(sampleSong)
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if err != nil {
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t.Error(err)
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}
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t.Log("bs = ", len(bs), "; bf =", len(bf), "bf(S) =", bytes.LastIndex(bf, []byte("S")))
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}
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func BenchmarkGetDuration(b *testing.B) {
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bs, bf, err := ReadFile(sampleSong)
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oggf, err := NewOggFile(sampleSong)
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if err != nil {
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b.Error(err)
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b.Fatal(err)
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}
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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GetDuration(bs, bf)
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oggf.GetDuration()
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}
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}
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func TestGetDuration(t *testing.T) {
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bs, bf, err := ReadFile(sampleSong)
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oggf, err := NewOggFile(sampleSong)
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if err != nil {
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t.Error(err)
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t.Fatal(err)
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}
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dur := GetDuration(bs, bf)
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dur := oggf.GetDuration()
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t.Log(dur, ((dur)/time.Second)*time.Second, dur.Milliseconds())
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}
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