public EncodingInfo Read( Stream raf )
{
EncodingInfo encodingInfo = new EncodingInfo();
//Begin info fetch-------------------------------------------
if ( raf.Length == 0 ) {
throw new CannotReadException("File is empty");
}
int id3TagSize = 0;
raf.Seek( 0 , SeekOrigin.Begin);
// skip id3v2 tag, because there may be long pictures inside with
// slows reading and they can be not unsyncronized
byte[] bbb = new byte[3];
raf.Read(bbb, 0, 3);
raf.Seek(0, SeekOrigin.Begin);
string ID3 = new string(System.Text.Encoding.ASCII.GetChars(bbb));
if (ID3 == "ID3") {
raf.Seek(6, SeekOrigin.Begin);
id3TagSize = ReadSyncsafeInteger(raf);
raf.Seek(id3TagSize+10, SeekOrigin.Begin);
}
MPEGFrame firstFrame = null;
byte[] b = new byte[4];
raf.Read(b, 0, b.Length);
// search for sync mark, but also for a right bitrate, samplerate and layer(that way you can
// read corrupted but playable files)
while ( !( (b[0]&0xFF)==0xFF && (b[1]&0xE0)==0xE0 && (b[1]&0x06)!=0 && (b[2]&0xF0)!=0xF0 && (b[2]&0x0C)!=0x0C ) && raf.Position < raf.Length-4) {
raf.Seek( -3, SeekOrigin.Current);
raf.Read(b, 0, b.Length);
}
firstFrame = new MPEGFrame( b );
if ( firstFrame == null || !firstFrame.Valid || firstFrame.SamplingRate == 0 ) {
//MP3File corrupted, no valid MPEG frames
throw new CannotReadException("Error: could not synchronize to first mp3 frame");
}
int firstFrameLength = firstFrame.FrameLength;
//----------------------------------------------------------------------------
int skippedLength = 0;
if ( firstFrame.MpegVersion == MPEGFrame.MPEG_VERSION_1 && firstFrame.ChannelMode == MPEGFrame.CHANNEL_MODE_MONO ) {
raf.Seek( 17, SeekOrigin.Current );
skippedLength += 17;
}
else if ( firstFrame.MpegVersion == MPEGFrame.MPEG_VERSION_1 ) {
raf.Seek( 32 , SeekOrigin.Current );
skippedLength += 32;
}
else if ( firstFrame.MpegVersion == MPEGFrame.MPEG_VERSION_2 && firstFrame.ChannelMode == MPEGFrame.CHANNEL_MODE_MONO ) {
raf.Seek(9, SeekOrigin.Current );
skippedLength += 9;
}
else if ( firstFrame.MpegVersion == MPEGFrame.MPEG_VERSION_2 ) {
raf.Seek( 17, SeekOrigin.Current );
skippedLength += 17;
}
int optionalFrameLength = 0;
byte[] xingPart1 = new byte[16];
raf.Read( xingPart1, 0, xingPart1.Length );
raf.Seek( 100 , SeekOrigin.Current );
byte[] xingPart2 = new byte[4];
raf.Read( xingPart2, 0, xingPart2.Length );
XingMPEGFrame currentXingFrame = new XingMPEGFrame( xingPart1, xingPart2 );
//System.err.println(currentXingFrame);
if ( !currentXingFrame.Valid )
raf.Seek( - 120 - skippedLength - 4 , SeekOrigin.Current ); //120 Xing bytes, unused skipped bytes and 4 mpeg info bytes
//Skipping Xing frame reading
else {
optionalFrameLength += 120;
byte[] lameHeader = new byte[36];
raf.Read( lameHeader, 0, lameHeader.Length);
LameMPEGFrame currentLameFrame = new LameMPEGFrame( lameHeader );
if ( !currentLameFrame.Valid )
raf.Seek( - 36 , SeekOrigin.Current );
//Skipping Lame frame reading
else
optionalFrameLength += 36;
//Lame Frame read
}
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
//Length computation
if ( currentXingFrame.Valid )
raf.Seek( firstFrameLength - ( skippedLength + optionalFrameLength + 4 ) , SeekOrigin.Current );
double timePerFrame = ((double) firstFrame.SampleNumber) / firstFrame.SamplingRate;
double lengthInSeconds;
if ( currentXingFrame.Valid ) {
//Preffered Method: extracts time length with the Xing Header (vbr:Xing or cbr:Info)********************
lengthInSeconds = ( timePerFrame * currentXingFrame.FrameCount );
encodingInfo.Vbr = currentXingFrame.IsVbr;
int fs = currentXingFrame.FileSize;
encodingInfo.Bitrate = (int)( ( (fs==0 ? raf.Length-id3TagSize : fs) * 8 ) / ( timePerFrame * currentXingFrame.FrameCount * 1000 ) );
}
else {
//Default Method: extracts time length using the file length and assuming CBR********************
int frameLength = firstFrame.FrameLength;
if (frameLength==0)
throw new CannotReadException("Error while reading header(maybe file is corrupted, or missing first mpeg frame before xing header)");
lengthInSeconds = timePerFrame * ((raf.Length-id3TagSize) / frameLength);
encodingInfo.Vbr = false;
encodingInfo.Bitrate = firstFrame.Bitrate ;
}
//Populates encodingInfo----------------------------------------------------
encodingInfo.Length = (int) lengthInSeconds;
encodingInfo.ChannelNumber = firstFrame.ChannelNumber;
encodingInfo.SamplingRate = firstFrame.SamplingRate;
encodingInfo.EncodingType = firstFrame.MpegVersionToString( firstFrame.MpegVersion ) + " || " + firstFrame.LayerToString( firstFrame.LayerVersion );
encodingInfo.ExtraEncodingInfos = "";
return encodingInfo;
}
public EncodingInfo Read(Stream raf)
{
EncodingInfo encodingInfo = new EncodingInfo();
//Begin info fetch-------------------------------------------
if (raf.Length == 0)
{
throw new CannotReadException("File is empty");
}
int id3TagSize = 0;
raf.Seek(0, SeekOrigin.Begin);
// skip id3v2 tag, because there may be long pictures inside with
// slows reading and they can be not unsyncronized
byte[] bbb = new byte[3];
raf.Read(bbb, 0, 3);
raf.Seek(0, SeekOrigin.Begin);
string ID3 = new string(System.Text.Encoding.ASCII.GetChars(bbb));
if (ID3 == "ID3")
{
raf.Seek(6, SeekOrigin.Begin);
id3TagSize = ReadSyncsafeInteger(raf);
raf.Seek(id3TagSize + 10, SeekOrigin.Begin);
}
MPEGFrame firstFrame = null;
byte[] b = new byte[4];
raf.Read(b, 0, b.Length);
// search for sync mark, but also for a right bitrate, samplerate and layer(that way you can
// read corrupted but playable files)
while (!((b[0] & 0xFF) == 0xFF && (b[1] & 0xE0) == 0xE0 && (b[1] & 0x06) != 0 && (b[2] & 0xF0) != 0xF0 && (b[2] & 0x0C) != 0x0C) && raf.Position < raf.Length - 4)
{
raf.Seek(-3, SeekOrigin.Current);
raf.Read(b, 0, b.Length);
}
firstFrame = new MPEGFrame(b);
if (firstFrame == null || !firstFrame.Valid || firstFrame.SamplingRate == 0)
{
//MP3File corrupted, no valid MPEG frames
throw new CannotReadException("Error: could not synchronize to first mp3 frame");
}
int firstFrameLength = firstFrame.FrameLength;
//----------------------------------------------------------------------------
int skippedLength = 0;
if (firstFrame.MpegVersion == MPEGFrame.MPEG_VERSION_1 && firstFrame.ChannelMode == MPEGFrame.CHANNEL_MODE_MONO)
{
raf.Seek(17, SeekOrigin.Current);
skippedLength += 17;
}
else if (firstFrame.MpegVersion == MPEGFrame.MPEG_VERSION_1)
{
raf.Seek(32, SeekOrigin.Current);
skippedLength += 32;
}
else if (firstFrame.MpegVersion == MPEGFrame.MPEG_VERSION_2 && firstFrame.ChannelMode == MPEGFrame.CHANNEL_MODE_MONO)
{
raf.Seek(9, SeekOrigin.Current);
skippedLength += 9;
}
else if (firstFrame.MpegVersion == MPEGFrame.MPEG_VERSION_2)
{
raf.Seek(17, SeekOrigin.Current);
skippedLength += 17;
}
int optionalFrameLength = 0;
byte[] xingPart1 = new byte[16];
raf.Read(xingPart1, 0, xingPart1.Length);
raf.Seek(100, SeekOrigin.Current);
byte[] xingPart2 = new byte[4];
raf.Read(xingPart2, 0, xingPart2.Length);
XingMPEGFrame currentXingFrame = new XingMPEGFrame(xingPart1, xingPart2);
//System.err.println(currentXingFrame);
if (!currentXingFrame.Valid)
{
raf.Seek(-120 - skippedLength - 4, SeekOrigin.Current); //120 Xing bytes, unused skipped bytes and 4 mpeg info bytes
}
//Skipping Xing frame reading
else
{
optionalFrameLength += 120;
byte[] lameHeader = new byte[36];
raf.Read(lameHeader, 0, lameHeader.Length);
LameMPEGFrame currentLameFrame = new LameMPEGFrame(lameHeader);
if (!currentLameFrame.Valid)
{
raf.Seek(-36, SeekOrigin.Current);
}
//Skipping Lame frame reading
else
{
optionalFrameLength += 36;
}
//Lame Frame read
}
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
//Length computation
if (currentXingFrame.Valid)
{
raf.Seek(firstFrameLength - (skippedLength + optionalFrameLength + 4), SeekOrigin.Current);
}
double timePerFrame = ((double)firstFrame.SampleNumber) / firstFrame.SamplingRate;
double lengthInSeconds;
if (currentXingFrame.Valid)
{
//Preffered Method: extracts time length with the Xing Header (vbr:Xing or cbr:Info)********************
lengthInSeconds = (timePerFrame * currentXingFrame.FrameCount);
encodingInfo.Vbr = currentXingFrame.IsVbr;
int fs = currentXingFrame.FileSize;
encodingInfo.Bitrate = (int)(((fs == 0 ? raf.Length - id3TagSize : fs) * 8) / (timePerFrame * currentXingFrame.FrameCount * 1000));
}
else
{
//Default Method: extracts time length using the file length and assuming CBR********************
int frameLength = firstFrame.FrameLength;
if (frameLength == 0)
{
throw new CannotReadException("Error while reading header(maybe file is corrupted, or missing first mpeg frame before xing header)");
}
lengthInSeconds = timePerFrame * ((raf.Length - id3TagSize) / frameLength);
encodingInfo.Vbr = false;
encodingInfo.Bitrate = firstFrame.Bitrate;
}
//Populates encodingInfo----------------------------------------------------
encodingInfo.Duration = new TimeSpan((long)lengthInSeconds * TimeSpan.TicksPerSecond);
encodingInfo.ChannelNumber = firstFrame.ChannelNumber;
encodingInfo.SamplingRate = firstFrame.SamplingRate;
encodingInfo.EncodingType = firstFrame.MpegVersionToString(firstFrame.MpegVersion) + " || " + firstFrame.LayerToString(firstFrame.LayerVersion);
encodingInfo.ExtraEncodingInfos = "";
return(encodingInfo);
}
