private void ParseForMp3Frames(Stream stream, bool enableSeeking)
{
Mp3Frame frame = null;
long offsetOfFirstFrame = 0;
stream = new BufferedStream(stream);
if (enableSeeking)
{
while (ID3v2.SkipTag(stream))
{
/* skip all id3 tags (see https://github.com/filoe/cscore/issues/63)
* there are some files with multiple id3v2 tags
* not sure whether this is according to the id3 specification but we have to handle it anyway
* as long as the SkipTag method returns true, another id3 tag has been found
*/
}
}
while (frame == null)
{
if (enableSeeking && stream.IsEndOfStream())
{
break;
}
if (enableSeeking)
{
offsetOfFirstFrame = stream.Position;
}
frame = Mp3Frame.FromStream(stream);
}
if (frame == null)
{
throw new Exception("Could not find any MP3-Frames in the stream.");
}
if (enableSeeking)
{
XingHeader xingHeader = XingHeader.FromFrame(frame);
if (xingHeader != null)
{
offsetOfFirstFrame = stream.Position;
}
}
_inputFormat = new Mp3Format(frame.SampleRate, frame.ChannelCount, frame.FrameLength, frame.BitRate);
//Prescan stream
if (enableSeeking)
{
_frameInfoCollection = new FrameInfoCollection();
while (_frameInfoCollection.AddFromMp3Stream(stream))
{
}
stream.Position = offsetOfFirstFrame;
}
}
/// <summary>
/// Gets the <see cref="XingHeader"/> of a <see cref="Mp3Frame"/>. If the <paramref name="frame"/> does not has an <see cref="XingHeader"/> the return value will be null.
/// </summary>
/// <param name="frame"><see cref="Mp3Frame"/> which should get checked whether it contains a <see cref="XingHeader"/>.</param>
/// <returns><see cref="XingHeader"/> of the specified <paramref name="frame"/> or null.</returns>
public static XingHeader FromFrame(Mp3Frame frame)
{
XingHeader header = new XingHeader();
int offset = CalcOffset(frame);
if (offset == -1)
{
return(null);
}
if (CheckForValidXingHeader(frame, offset))
{
header._startIndex = offset;
offset = offset + 4;
}
else
{
return(null);
}
header.HeaderFlags = (XingHeaderFlags)ReadHeaderFlags(frame, offset);
offset = offset + 4;
if ((header.HeaderFlags & XingHeaderFlags.Frames) != 0)
{
header._framesOffset = offset;
offset += 4;
}
if ((header.HeaderFlags & XingHeaderFlags.Bytes) != 0)
{
header._bytesOffset = offset;
offset += 4;
}
if ((header.HeaderFlags & XingHeaderFlags.Toc) != 0)
{
header._tocOffset = offset;
offset += 100;
}
if ((header.HeaderFlags & XingHeaderFlags.QualityIndicator) != 0)
{
header._qualityIndicator = ReadHeaderFlags(frame, offset);
offset += 4;
}
header._endIndex = offset;
return(header);
}
