VBRInfo ParseVBRI()
{
VBRInfo info = new VBRInfo();
info.Channels = Channels;
info.SampleRate = SampleRate;
info.SampleCount = SampleCount;
// VBRI is "fixed" size... Yay. :)
var buf = new byte[26];
if (Read(36, buf) != 26)
{
return(null);
}
// Version
var version = buf[4] << 8 | buf[5];
// Delay
info.VBRDelay = buf[6] << 8 | buf[7];
// Quality
info.VBRQuality = buf[8] << 8 | buf[9];
// Bytes
info.VBRBytes = buf[10] << 24 | buf[11] << 16 | buf[12] << 8 | buf[13];
// Frames
info.VBRFrames = buf[14] << 24 | buf[15] << 16 | buf[16] << 8 | buf[17];
// TOC
// entries
var tocEntries = buf[18] << 8 | buf[19];
var tocScale = buf[20] << 8 | buf[21];
var tocEntrySize = buf[22] << 8 | buf[23];
var tocFramesPerEntry = buf[24] << 8 | buf[25];
var tocSize = tocEntries * tocEntrySize;
var toc = new byte[tocSize];
if (Read(62, toc) != tocSize)
{
return(null);
}
return(info);
}
public bool ParseVBR(out VBRInfo info)
{
Span <byte> buf = stackalloc byte[4];
// Xing first
int offset;
if (Version == MpegVersion.Version1 && ChannelMode != MpegChannelMode.Mono)
{
offset = 32 + 4;
}
else if (Version > MpegVersion.Version1 && ChannelMode == MpegChannelMode.Mono)
{
offset = 9 + 4;
}
else
{
offset = 17 + 4;
}
if (Read(offset, buf) == 4)
{
if (buf[0] == 'X' && buf[1] == 'i' && buf[2] == 'n' && buf[3] == 'g' ||
buf[0] == 'I' && buf[1] == 'n' && buf[2] == 'f' && buf[3] == 'o')
{
return(ParseXing(offset + 4, out info));
}
// then VBRI (kinda rare)
if (Read(36, buf) == 4)
{
if (buf[0] == 'V' && buf[1] == 'B' && buf[2] == 'R' && buf[3] == 'I')
{
return(ParseVBRI(out info));
}
}
}
info = default;
return(false);
}
private bool ParseVBRI(out VBRInfo info)
{
info = new VBRInfo();
info.Channels = Channels;
info.SampleRate = SampleRate;
info.SampleCount = SampleCount;
// VBRI is "fixed" size... Yay. :)
Span <byte> buf = stackalloc byte[26];
if (Read(36, buf) != 26)
{
return(false);
}
int version = BinaryPrimitives.ReadInt16BigEndian(buf.Slice(4));
info.VBRDelay = BinaryPrimitives.ReadInt16BigEndian(buf.Slice(6));
info.VBRQuality = BinaryPrimitives.ReadInt16BigEndian(buf.Slice(8));
info.VBRBytes = BinaryPrimitives.ReadInt32BigEndian(buf.Slice(10));
info.VBRFrames = BinaryPrimitives.ReadInt32BigEndian(buf.Slice(14));
// TOC
// entries
int tocEntries = BinaryPrimitives.ReadInt16BigEndian(buf.Slice(18));
int tocScale = BinaryPrimitives.ReadInt16BigEndian(buf.Slice(20));
int tocEntrySize = BinaryPrimitives.ReadInt16BigEndian(buf.Slice(22));
int tocFramesPerEntry = BinaryPrimitives.ReadInt16BigEndian(buf.Slice(24));
int tocSize = tocEntries * tocEntrySize;
var toc = new byte[tocSize];
if (Read(62, toc) != tocSize)
{
return(false);
}
return(true);
}
VBRInfo ParseXing(int offset)
{
VBRInfo info = new VBRInfo();
info.Channels = Channels;
info.SampleRate = SampleRate;
info.SampleCount = SampleCount;
var buf = new byte[100];
if (Read(offset, buf, 0, 4) != 4)
{
return(null);
}
offset += 4;
var flags = buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
// frame count
if ((flags & 0x1) != 0)
{
if (Read(offset, buf, 0, 4) != 4)
{
return(null);
}
offset += 4;
info.VBRFrames = buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
}
// byte count
if ((flags & 0x2) != 0)
{
if (Read(offset, buf, 0, 4) != 4)
{
return(null);
}
offset += 4;
info.VBRBytes = buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
}
// TOC
if ((flags & 0x4) != 0)
{
// we're not using the TOC, so just discard it
if (Read(offset, buf) != 100)
{
return(null);
}
offset += 100;
}
// scale
if ((flags & 0x8) != 0)
{
if (Read(offset, buf, 0, 4) != 4)
{
return(null);
}
offset += 4;
info.VBRQuality = buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
}
//// now look for a LAME header (note: if it isn't found, it doesn't fail the VBR parse)
//do
//{
// if (Read(offset, buf, 0, 20) != 20) break;
// offset += 20;
// // LAME tag revision: only 0 and 1 are valid
// if ((buf[9] & 0xF0) > 0x10) break;
// // VBR mode: 0-6, 8 & 9 are valid
// var mode = buf[9] & 0xF;
// if (mode == 7 || mode > 9) break;
// // Lowpass filter value
// var lowpass = buf[10] / 100.0;
// // Replay Gain
// var rgPeak = BitConverter.ToSingle(buf, 11);
// var rgGainRadio = buf[15] << 8 | buf[16];
// var rgGain = buf[17] << 8 | buf[18];
//} while (false);
return(info);
}
FrameBase FindNextFrame()
{
// if we've found the end, don't bother looking for anything else
if (_endFound)
{
return(null);
}
var freeFrame = _lastFree;
var lastFrameStart = _readOffset;
lock (_frameLock)
{
// read 3 bytes
var syncBuf = new byte[4];
try
{
if (Read(_readOffset, syncBuf, 0, 4) == 4)
{
// now loop until a frame is found
do
{
var sync = (uint)(syncBuf[0] << 24 | syncBuf[1] << 16 | syncBuf[2] << 8 | syncBuf[3]);
lastFrameStart = _readOffset;
// try ID3 first (for v2 frames)
if (_id3Frame == null)
{
var f = ID3Frame.TrySync(sync);
if (f != null)
{
if (f.Validate(_readOffset, this))
{
if (!_canSeek)
{
f.SaveBuffer();
}
_readOffset += f.Length;
DiscardThrough(_readOffset, true);
return(_id3Frame = f);
}
}
}
// now look for a RIFF header
if (_first == null && _riffHeaderFrame == null)
{
var f = RiffHeaderFrame.TrySync(sync);
if (f != null)
{
if (f.Validate(_readOffset, this))
{
_readOffset += f.Length;
DiscardThrough(_readOffset, true);
return(_riffHeaderFrame = f);
}
}
}
// finally, just try for an MPEG frame
var frame = MpegFrame.TrySync(sync);
if (frame != null)
{
if (frame.Validate(_readOffset, this) &&
!(freeFrame != null &&
(frame.Layer != freeFrame.Layer ||
frame.Version != freeFrame.Version ||
frame.SampleRate != freeFrame.SampleRate ||
frame.BitRateIndex > 0
)
)
)
{
if (!_canSeek)
{
frame.SaveBuffer();
DiscardThrough(_readOffset + frame.FrameLength, true);
}
_readOffset += frame.FrameLength;
if (_first == null)
{
if (_vbrInfo == null && (_vbrInfo = frame.ParseVBR()) != null)
{
return(FindNextFrame());
}
else
{
frame.Number = 0;
_first = _last = frame;
}
}
else
{
if (frame.SampleCount != _first.SampleCount)
{
_mixedFrameSize = true;
}
frame.SampleOffset = _last.SampleCount + _last.SampleOffset;
frame.Number = _last.Number + 1;
_last = (_last.Next = frame);
}
if (frame.BitRateIndex == 0)
{
_lastFree = frame;
}
return(frame);
}
}
// if we've read MPEG frames and can't figure out what frame type we have, try looking for a new ID3 tag
if (_last != null)
{
var f = ID3Frame.TrySync(sync);
if (f != null)
{
if (f.Validate(_readOffset, this))
{
if (!_canSeek)
{
f.SaveBuffer();
}
// if it's a v1 tag, go ahead and parse it
if (f.Version == 1)
{
_id3v1Frame = f;
}
else
{
// grrr... the ID3 2.4 spec says tags can be anywhere in the file and that later tags can override earlier ones... boo
_id3Frame.Merge(f);
}
_readOffset += f.Length;
DiscardThrough(_readOffset, true);
return(f);
}
}
}
// well, we didn't find anything, so rinse and repeat with the next byte
++_readOffset;
if (_first == null || !_canSeek)
{
DiscardThrough(_readOffset, true);
}
Buffer.BlockCopy(syncBuf, 1, syncBuf, 0, 3);
} while (Read(_readOffset + 3, syncBuf, 3, 1) == 1);
}
// move the "end of frame" marker for the last free format frame (in case we have one)
// this is because we don't include the last four bytes otherwise
lastFrameStart += 4;
_endFound = true;
return(null);
}
finally
{
if (freeFrame != null)
{
freeFrame.Length = (int)(lastFrameStart - freeFrame.Offset);
if (!_canSeek)
{
// gotta finish filling the buffer!!
throw new InvalidOperationException("Free frames cannot be read properly from forward-only streams!");
}
// if _lastFree hasn't changed (we got a non-MPEG frame), clear it out
if (_lastFree == freeFrame)
{
_lastFree = null;
}
}
}
}
}
private bool ParseXing(int offset, out VBRInfo info)
{
info = new VBRInfo();
info.Channels = Channels;
info.SampleRate = SampleRate;
info.SampleCount = SampleCount;
Span <byte> buf = stackalloc byte[100];
if (Read(offset, buf.Slice(0, 4)) != 4)
{
return(false);
}
offset += 4;
int flags = BinaryPrimitives.ReadInt32BigEndian(buf);
// frame count
if ((flags & 0x1) != 0)
{
if (Read(offset, buf.Slice(0, 4)) != 4)
{
return(false);
}
offset += 4;
info.VBRFrames = BinaryPrimitives.ReadInt32BigEndian(buf);
}
// byte count
if ((flags & 0x2) != 0)
{
if (Read(offset, buf.Slice(0, 4)) != 4)
{
return(false);
}
offset += 4;
info.VBRBytes = BinaryPrimitives.ReadInt32BigEndian(buf);
}
// TOC
if ((flags & 0x4) != 0)
{
// we're not using the TOC, so just discard it
if (Read(offset, buf) != 100)
{
return(false);
}
offset += 100;
}
// scale
if ((flags & 0x8) != 0)
{
if (Read(offset, buf.Slice(0, 4)) != 4)
{
return(false);
}
offset += 4;
info.VBRQuality = BinaryPrimitives.ReadInt32BigEndian(buf);
}
//// now look for a LAME header (note: if it isn't found, it doesn't fail the VBR parse)
//do
//{
// if (Read(offset, buf, 0, 20) != 20) break;
// offset += 20;
// // LAME tag revision: only 0 and 1 are valid
// if ((buf[9] & 0xF0) > 0x10) break;
// // VBR mode: 0-6, 8 & 9 are valid
// var mode = buf[9] & 0xF;
// if (mode == 7 || mode > 9) break;
// // Lowpass filter value
// var lowpass = buf[10] / 100.0;
// // Replay Gain
// var rgPeak = BitConverter.ToSingle(buf, 11);
// var rgGainRadio = buf[15] << 8 | buf[16];
// var rgGain = buf[17] << 8 | buf[18];
//}
//while (false);
return(true);
}
VBRInfo ParseVBRI()
{
VBRInfo info = new VBRInfo();
info.Channels = Channels;
info.SampleRate = SampleRate;
info.SampleCount = SampleCount;
// VBRI is "fixed" size... Yay. :)
var buf = new byte[26];
if (Read(36, buf) != 26) return null;
// Version
var version = buf[4] << 8 | buf[5];
// Delay
info.VBRDelay = buf[6] << 8 | buf[7];
// Quality
info.VBRQuality = buf[8] << 8 | buf[9];
// Bytes
info.VBRBytes = buf[10] << 24 | buf[11] << 16 | buf[12] << 8 | buf[13];
// Frames
info.VBRFrames = buf[14] << 24 | buf[15] << 16 | buf[16] << 8 | buf[17];
// TOC
// entries
var tocEntries = buf[18] << 8 | buf[19];
var tocScale = buf[20] << 8 | buf[21];
var tocEntrySize = buf[22] << 8 | buf[23];
var tocFramesPerEntry = buf[24] << 8 | buf[25];
var tocSize = tocEntries * tocEntrySize;
var toc = new byte[tocSize];
if (Read(62, toc) != tocSize) return null;
return info;
}
VBRInfo ParseXing(int offset)
{
VBRInfo info = new VBRInfo();
info.Channels = Channels;
info.SampleRate = SampleRate;
info.SampleCount = SampleCount;
var buf = new byte[100];
if (Read(offset, buf, 0, 4) != 4) return null;
offset += 4;
var flags = buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
// frame count
if ((flags & 0x1) != 0)
{
if (Read(offset, buf, 0, 4) != 4) return null;
offset += 4;
info.VBRFrames = buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
}
// byte count
if ((flags & 0x2) != 0)
{
if (Read(offset, buf, 0, 4) != 4) return null;
offset += 4;
info.VBRBytes = buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
}
// TOC
if ((flags & 0x4) != 0)
{
// we're not using the TOC, so just discard it
if (Read(offset, buf) != 100) return null;
offset += 100;
}
// scale
if ((flags & 0x8) != 0)
{
if (Read(offset, buf, 0, 4) != 4) return null;
offset += 4;
info.VBRQuality = buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
}
//// now look for a LAME header (note: if it isn't found, it doesn't fail the VBR parse)
//do
//{
// if (Read(offset, buf, 0, 20) != 20) break;
// offset += 20;
// // LAME tag revision: only 0 and 1 are valid
// if ((buf[9] & 0xF0) > 0x10) break;
// // VBR mode: 0-6, 8 & 9 are valid
// var mode = buf[9] & 0xF;
// if (mode == 7 || mode > 9) break;
// // Lowpass filter value
// var lowpass = buf[10] / 100.0;
// // Replay Gain
// var rgPeak = BitConverter.ToSingle(buf, 11);
// var rgGainRadio = buf[15] << 8 | buf[16];
// var rgGain = buf[17] << 8 | buf[18];
//} while (false);
return info;
}
FrameBase FindNextFrame()
{
// if we've found the end, don't bother looking for anything else
if (_endFound) return null;
var freeFrame = _lastFree;
var lastFrameStart = _readOffset;
lock (_frameLock)
{
// read 3 bytes
var syncBuf = new byte[4];
try
{
if (Read(_readOffset, syncBuf, 0, 4) == 4)
{
// now loop until a frame is found
do
{
var sync = (uint)(syncBuf[0] << 24 | syncBuf[1] << 16 | syncBuf[2] << 8 | syncBuf[3]);
lastFrameStart = _readOffset;
// try ID3 first (for v2 frames)
if (_id3Frame == null)
{
var f = ID3Frame.TrySync(sync);
if (f != null)
{
if (f.Validate(_readOffset, this))
{
if (!_canSeek) f.SaveBuffer();
_readOffset += f.Length;
DiscardThrough(_readOffset, true);
return _id3Frame = f;
}
}
}
// now look for a RIFF header
if (_first == null && _riffHeaderFrame == null)
{
var f = RiffHeaderFrame.TrySync(sync);
if (f != null)
{
if (f.Validate(_readOffset, this))
{
_readOffset += f.Length;
DiscardThrough(_readOffset, true);
return _riffHeaderFrame = f;
}
}
}
// finally, just try for an MPEG frame
var frame = MpegFrame.TrySync(sync);
if (frame != null)
{
if (frame.Validate(_readOffset, this)
&& !(freeFrame != null
&& (frame.Layer != freeFrame.Layer
|| frame.Version != freeFrame.Version
|| frame.SampleRate != freeFrame.SampleRate
|| frame.BitRateIndex > 0
)
)
)
{
if (!_canSeek)
{
frame.SaveBuffer();
DiscardThrough(_readOffset + frame.FrameLength, true);
}
_readOffset += frame.FrameLength;
if (_first == null)
{
if (_vbrInfo == null && (_vbrInfo = frame.ParseVBR()) != null)
{
return FindNextFrame();
}
else
{
frame.Number = 0;
_first = _last = frame;
}
}
else
{
if (frame.SampleCount != _first.SampleCount)
{
_mixedFrameSize = true;
}
frame.SampleOffset = _last.SampleCount + _last.SampleOffset;
frame.Number = _last.Number + 1;
_last = (_last.Next = frame);
}
if (frame.BitRateIndex == 0)
{
_lastFree = frame;
}
return frame;
}
}
// if we've read MPEG frames and can't figure out what frame type we have, try looking for a new ID3 tag
if (_last != null)
{
var f = ID3Frame.TrySync(sync);
if (f != null)
{
if (f.Validate(_readOffset, this))
{
if (!_canSeek) f.SaveBuffer();
// if it's a v1 tag, go ahead and parse it
if (f.Version == 1)
{
_id3v1Frame = f;
}
else
{
// grrr... the ID3 2.4 spec says tags can be anywhere in the file and that later tags can override earlier ones... boo
_id3Frame.Merge(f);
}
_readOffset += f.Length;
DiscardThrough(_readOffset, true);
return f;
}
}
}
// well, we didn't find anything, so rinse and repeat with the next byte
++_readOffset;
if (_first == null || !_canSeek) DiscardThrough(_readOffset, true);
Buffer.BlockCopy(syncBuf, 1, syncBuf, 0, 3);
} while (Read(_readOffset + 3, syncBuf, 3, 1) == 1);
}
// move the "end of frame" marker for the last free format frame (in case we have one)
// this is because we don't include the last four bytes otherwise
lastFrameStart += 4;
_endFound = true;
return null;
}
finally
{
if (freeFrame != null)
{
freeFrame.Length = (int)(lastFrameStart - freeFrame.Offset);
if (!_canSeek)
{
// gotta finish filling the buffer!!
throw new InvalidOperationException("Free frames cannot be read properly from forward-only streams!");
}
// if _lastFree hasn't changed (we got a non-MPEG frame), clear it out
if (_lastFree == freeFrame)
{
_lastFree = null;
}
}
}
}
}
