/// <summary>
/// Add invalid data (since we need to check garbage for a mp3 resync we may need to combine multiple invalid chunks).
/// </summary>
/// <param name="buffer">The buffer to add to invalid data frame.</param>
void InvalidData(byte[] buffer)
{
if (buffer.Length == 0)
{
return;
}
if (m_InvalidFrame == null)
{
m_InvalidFrame = new MP3InvalidFrame();
}
m_InvalidFrame.Add(buffer);
}
/// <summary>
/// Gets the next frame.
/// </summary>
/// <returns>Returns the next frame or null (at end of stream).</returns>
public AudioFrame GetNextFrame()
{
while (true)
{
#region return buffered frames first (if any)
// got a decoded frame at the cache ?
if (m_BufferedFrame != null)
{
AudioFrame result;
if (m_InvalidFrame != null)
{
result = m_InvalidFrame;
m_InvalidFrame = null;
}
else
{
result = m_BufferedFrame;
m_BufferedFrame = null;
}
return(result);
}
#endregion
#region search next frame start
// search the next interesting position
var searchResult = FindFrame();
if (searchResult == null)
{
#region end of stream cleanup
// invalid data at end of stream ?
if (m_Reader.Available > 0)
{
// yes buffer
InvalidData(m_Reader.GetBuffer());
}
// got an invalid frame ?
if (m_InvalidFrame != null)
{
// return invalid frame
AudioFrame result = m_InvalidFrame;
m_InvalidFrame = null;
return(result);
}
// got an id3v1 ?
if (m_ID3v1 != null)
{
// return id3v1
AudioFrame result = m_ID3v1;
m_ID3v1 = null;
return(result);
}
// everything done, return null
return(null);
#endregion
}
#endregion
#region check search result
// got garbage at the beginning?
if (searchResult.Index > 0)
{
// yes, invalid data
InvalidData(m_Reader.GetBuffer(searchResult.Index));
continue;
}
#endregion
#region decode frame
// try to decode frame
try
{
var valid = false;
AudioFrame frame = null;
switch (searchResult.Match)
{
#region decode mp3 frame
case MatchType.MP3Frame:
var audioFrame = new MP3AudioFrame();
valid = audioFrame.Parse(m_Reader);
frame = audioFrame;
break;
#endregion
#region decode id3 frame
case MatchType.ID3Frame:
frame = new ID3v2();
valid = frame.Parse(m_Reader);
break;
#endregion
default: throw new NotImplementedException(string.Format("Unknown frame type {0}", searchResult.Match));
}
// parsed successfully?
if (valid)
{
// yes, cache frame
m_BufferedFrame = frame;
}
else
{
// no invalidate
InvalidData(m_Reader.GetBuffer(1));
}
}
catch (Exception ex)
{
Trace.TraceError(string.Format("Error while decoding {0} in stream {1}", searchResult.Match, m_Reader));
Trace.TraceError(ex.ToString());
// invalid frame or decoder error, move ahead
var count = (searchResult.Index < 0) ? 1 : searchResult.Index + 1;
InvalidData(m_Reader.GetBuffer(count));
}
#endregion
}
}