/**
* tries to find the next MPEG Audio Frame, loads it into the destination
* buffer (including 32bit header) and returns a FrameHeader object. (If
* destFH is non-null, that object will be used to store the header infos)
* will block until data is available. will throw EOFException of any other
* IOException created by the InputStream object. set filter to 0 or to any
* other value using the FILTER_xxx flags to force a specific frame type.
*/
func (p *mpaFrameParser) getNextFrame(filter uint32, destBuffer []byte, destFH *mp3agic.FrameHeader) (*mp3agic.FrameHeader, os.Error) {
p.setupFilter(filter)
fill(p.headBuff[:], 0)
hbPos := 0
fh := destFH
if fh == nil {
fh = new(mp3agic.FrameHeader)
}
var tmp [1]byte
skipped := -4
for {
readn, err := p.ips.Read(tmp[:])
if readn == 0 && err == os.EOF { // EOF ?
if p.junkh != nil {
for i := 0; i < 4; i++ { // flush headBuff
if skipped >= 0 {
p.junkh.Write(p.headBuff[(hbPos+i)&3])
}
skipped++
}
p.junkh.EndOfJunkBlock()
}
return nil, os.EOF
} else if err != os.EOF {
return nil, err
}
if p.junkh != nil && skipped >= 0 {
p.junkh.Write(p.headBuff[hbPos])
}
p.headBuff[hbPos] = tmp[0]
skipped++
hbPos = (hbPos + 1) & 3
if p.headBuff[hbPos] != 0xFF {
continue // not the beginning of a sync-word
}
header32 := uint32(p.headBuff[hbPos])
for z := 1; z < 4; z++ {
header32 <<= 8
header32 |= uint32(p.headBuff[(hbPos+z)&3])
}
if header32&p.masker != p.masked {
continue // not a frame header
}
*fh = mp3agic.FrameHeader(header32)
if fh.Verify() != nil { // doesn't look like a proper header
continue
}
if filter&FILTER_STEREO != 0 && fh.Channels() != 2 {
continue
}
offs := 0
for ; offs < 4; offs++ {
destBuffer[offs] = p.headBuff[(hbPos+offs)&3]
}
tmp2 := fh.LengthInBytes() - offs
//tmp2 := fh.getFrameSize() - offs;
// FIXME: behaviour when not enough data read (different from Java)
readn, err = p.ips.Read(destBuffer[offs : offs+tmp2])
if readn != tmp2 {
if err != os.EOF {
panic(err)
}
if p.junkh != nil {
readn += 4 // inklusive header
for z := 0; z < readn; z++ {
p.junkh.Write(destBuffer[z] & 0xFF)
}
p.junkh.EndOfJunkBlock()
}
return nil, err
}
if p.junkh != nil {
p.junkh.EndOfJunkBlock()
}
break
}
return fh, nil
}
func createHeaderFrame(toBeSimilar mp3agic.FrameHeader, vbr bool, kbps float32,
frameCount, musicBytes, vbrScale int, seektable []byte,
encDelay, encPadding int, srcTag *XingInfoLameTagFrame, dest []byte, dofs int,
maskATH int) int {
fh32 := toBeSimilar | 0x00010000 // disable CRC if any
frameSize := 0
tagOffset := 0
{ // calculate optimal header frame size
tmp := mp3agic.FrameHeader()
minDist := float32(9999)
for i := 1; i < 15; i++ {
var th32 int = (fh32 & 0xFFFF0FFF) | (i << 12)
tmp.setHeader32(th32)
if tmp.getFrameSize() >= 0xC0 {
var ikbps int = tmp.BitrateInKbps()
var dist float32 = Math.abs(kbps - ikbps)
if dist < minDist {
minDist = dist
fh32 = th32
frameSize = tmp.getFrameSize()
tagOffset = tmp.getSideInfoSize() + 4
}
}
}
}
tagOffset += dofs
fill(dest[dofs:dofs+frameSize], 0)
//Arrays.fill(dest, dofs, dofs + frameSize, (byte) 0);
dest[dofs] = byte(fh32 >> 24)
dest[dofs+1] = byte(fh32 >> 16)
dest[dofs+2] = byte(fh32 >> 8)
dest[dofs+3] = byte(fh32)
if vbr {
copy(dest, "Xing")
} else {
copy(dest, "Info")
}
tagOffset += 4
copy(dest, []byte{0, 0, 0, 0x0f})
tagOffset += 4
add := func(b byte) {
dest[tagOffset] = b
tagOffset++
}
add32 := func(i uint32) {
add(byte(i >> 24))
add(byte(i >> 16))
add(byte(i >> 8))
add(byte(i))
}
add32(uint32(frameCount))
add32(uint32(frameSize + musicBytes))
copy(dest[tagOffset:tagOffset+100], seektable)
//System.arraycopy(seektable, 0, dest, tagOffset, 100);
tagOffset += 100
add32(uint32(vbrScale))
if srcTag != nil && srcTag.Verify() == nil && srcTag.hasLameTag {
copy(dest[tagOffset-4:], srcTag.bb[srcTag.lameTagOfs:srcTag.lameTagOfs+40])
//System.arraycopy(srcTag.bb, srcTag.lameTagOfs, dest, tagOffset - 4, 40);
tagOffset += 4
// delete LAME's replaygain tag
for i := 0; i < 8; i++ {
dest[tagOffset+0x07+i] = 0
}
// deleting no-gap flags ...
dest[tagOffset+0x0F] &= maskATH
} else {
copy(dest, "LAME")
tagOffset += 4
}
encDelay = max(0, min(encDelay, 4095))
encPadding = max(0, min(encPadding, 4095))
tagOffset += 0x11
// write encDelay / encPadding ...
add(byte(uint32(encDelay) >> 4))
add(byte(((encDelay & 0xF) << 4) | (uint32(encPadding) >> 8)))
add(byte(encPadding))
tagOffset += 4
add32(uint32(frameSize + musicBytes))
crc = uint16(0)
for i := 0; i < 190; i++ {
crc = CRC16.updateLAME(crc, dest[dofs+i])
}
tagOffset += 6
add(byte(crc >> 8))
add(byte(crc))
return frameSize
}