public Mp3Reader(FileInfo file)
{
_file = file;
_fileStream = new FileStream(file.FullName, FileMode.Open, FileAccess.Read, FileShare.Read, 65536);
// Analyze keyframes data
AnalyzeKeyFrames();
_firstFrame = true;
// Process ID3v2 header if present
ProcessID3v2Header();
// Create file metadata object
_fileMeta = CreateFileMeta();
// MP3 header is length of 32 bits, that is, 4 bytes
// Read further if there's still data
if (_fileStream.Length - _fileStream.Position > 4)
{
// Look to next frame
SearchNextFrame();
// Save position
long pos = _fileStream.Position;
// Read header...
// Data in MP3 file goes header-data-header-data...header-data
Mp3Header header = ReadHeader();
// Set position
_fileStream.Position = pos;
// Check header
if (header != null)
{
CheckValidHeader(header);
}
else
{
throw new NotSupportedException("No initial header found.");
}
}
}
/// <summary>
/// Check if the file can be played back with Flash. Supported sample rates are 44KHz, 22KHz, 11KHz and 5.5KHz
/// </summary>
/// <param name="header"></param>
private void CheckValidHeader(Mp3Header header)
{
switch (header.SampleRate)
{
case 44100:
case 22050:
case 11025:
case 5513:
// Supported sample rate
break;
default:
throw new NotSupportedException("Unsupported sample rate: " + header.SampleRate);
}
}
private Mp3Header ReadHeader()
{
Mp3Header header = null;
while (header == null && (_fileStream.Length - _fileStream.Position) > 4)
{
try {
byte[] buffer = new byte[4];
_fileStream.Read(buffer, 0, 4);
header = new Mp3Header(buffer);
} catch (IOException ex) {
log.Error("MP3Reader ReadTag", ex);
break;
} catch (Exception) {
SearchNextFrame();
}
}
return(header);
}
public bool HasMoreTags()
{
Mp3Header header = null;
while (header == null && (_fileStream.Length - _fileStream.Position) > 4)
{
try {
byte[] buffer = new byte[4];
_fileStream.Read(buffer, 0, 4);
header = new Mp3Header(buffer);
} catch (IOException ex) {
log.Error("MP3Reader HasMoreTags", ex);
break;
} catch (Exception) {
SearchNextFrame();
}
}
if (header == null)
{
return(false);
}
if (header.FrameSize == 0)
{
// TODO find better solution how to deal with broken files...
// See APPSERVER-62 for details
return(false);
}
if (_fileStream.Position + header.FrameSize - 4 > _fileStream.Length)
{
// Last frame is incomplete
_fileStream.Position = _fileStream.Length;
return(false);
}
_fileStream.Position = _fileStream.Position - 4;
return(true);
}
public KeyFrameMeta AnalyzeKeyFrames()
{
lock (_syncLock) {
if (_frameMeta != null)
{
return(_frameMeta);
}
#if !NET_1_1
List <long> positionList = new List <long>();
List <double> timestampList = new List <double>();
#else
ArrayList positionList = new ArrayList();
ArrayList timestampList = new ArrayList();
#endif
_dataRate = 0;
long rate = 0;
int count = 0;
long origPos = _fileStream.Position;
double time = 0;
_fileStream.Position = 0;
ProcessID3v2Header();
SearchNextFrame();
while (this.HasMoreTags())
{
Mp3Header header = ReadHeader();
if (header == null)
{
// No more tags
break;
}
if (header.FrameSize == 0)
{
// TODO find better solution how to deal with broken files...
// See APPSERVER-62 for details
break;
}
long pos = _fileStream.Position - 4;
if (pos + header.FrameSize > _fileStream.Length)
{
// Last frame is incomplete
break;
}
positionList.Add(pos);
timestampList.Add(time);
rate += header.BitRate / 1000;
time += header.FrameDuration;
_fileStream.Position = pos + header.FrameSize;
count++;
}
// restore the pos
_fileStream.Position = origPos;
_duration = (long)time;
_dataRate = (int)(rate / count);
#if !NET_1_1
_posTimeMap = new Dictionary <long, double>();
#else
_posTimeMap = new Hashtable();
#endif
_frameMeta = new KeyFrameMeta();
_frameMeta.Duration = _duration;
_frameMeta.Positions = new long[positionList.Count];
_frameMeta.Timestamps = new int[timestampList.Count];
_frameMeta.AudioOnly = true;
for (int i = 0; i < _frameMeta.Positions.Length; i++)
{
_frameMeta.Positions[i] = (int)positionList[i];
_frameMeta.Timestamps[i] = (int)timestampList[i];
_posTimeMap.Add(positionList[i], timestampList[i]);
}
return(_frameMeta);
}
}
public ITag ReadTag()
{
lock (_syncLock) {
if (_firstFrame)
{
// Return file metadata as first tag.
_firstFrame = false;
return(_fileMeta);
}
Mp3Header header = ReadHeader();
if (header == null)
{
return(null);
}
int frameSize = header.FrameSize;
if (frameSize == 0)
{
// TODO find better solution how to deal with broken files...
// See APPSERVER-62 for details
return(null);
}
if (_fileStream.Position + frameSize - 4 > _fileStream.Length)
{
// Last frame is incomplete
_fileStream.Position = _fileStream.Length;
return(null);
}
_tag = new Tag(IOConstants.TYPE_AUDIO, (int)_currentTime, frameSize + 1, null, _prevSize);
_prevSize = frameSize + 1;
_currentTime += header.FrameDuration;
byte[] buffer = new byte[_tag.BodySize];
//ByteBuffer body = ByteBuffer.Allocate(_tag.BodySize);
byte tagType = (byte)((IOConstants.FLAG_FORMAT_MP3 << 4) | (IOConstants.FLAG_SIZE_16_BIT << 1));
switch (header.SampleRate)
{
case 44100:
tagType |= (byte)(IOConstants.FLAG_RATE_44_KHZ << 2);
break;
case 22050:
tagType |= (byte)(IOConstants.FLAG_RATE_22_KHZ << 2);
break;
case 11025:
tagType |= (byte)(IOConstants.FLAG_RATE_11_KHZ << 2);
break;
default:
tagType |= (byte)(IOConstants.FLAG_RATE_5_5_KHZ << 2);
break;
}
tagType |= (header.IsStereo ? IOConstants.FLAG_TYPE_STEREO : IOConstants.FLAG_TYPE_MONO);
/*
* body.Put(tagType);
* body.PutInt(header.Data);
* byte[] buffer = new byte[frameSize - 4];
* _fileStream.Read(buffer, 0, buffer.Length);
* body.Put(buffer);
* body.Flip();
* _tag.Body = body.ToArray();
*/
buffer[0] = tagType;
Array.Copy(header.Data, 0, buffer, 1, 4);
_fileStream.Read(buffer, 5, frameSize - 4);
_tag.Body = buffer;
return(_tag);
}
}
