/// <summary>
/// Search audio stream using passed MpegStreamManager
/// </summary>
public bool Parse(ref MpegStreamManager msManager)
{
audioStream = new MpegAudioStream();
long offset = 0;
// Search 0x00 0x00 0x01 0xC0 marker [Audio Stream]
bool isAudioContains =
msManager.SearchMarker(ref offset, new byte[4]{0x00, 0x00, 0x01, 0xC0});
if (!isAudioContains)
{
// there isn't audio
return false;
}
offset += 13;
bool isAudio = false;
while (!isAudio && offset < (msManager.StreamSize - 10))
{
if ((msManager.GetByte(offset) == 0xFF) &&
(msManager.GetByte(offset + 1) & 0xF0) == 0xF0)
{
isAudio = ParseAudioStream(ref msManager, offset);
}
offset ++;
}
if (isAudio)
{
// Audio information added
return true;
}
return false;
}
/// <summary>
/// Search video stream using passed MpegStreamManager
/// </summary>
public bool Parse(ref MpegStreamManager msManager)
{
videoStream = new MpegVideoStream();
long offset = 0;
// Search 0x00 0x00 0x01 0xB3 marker [Sequence header]
bool isSeqHeader = msManager.SearchMarker(ref offset,
new byte[4]{0x00, 0x00, 0x01, 0xB3});
if (!isSeqHeader)
{
// Sequence header not founded
return false;
}
// skip marker bytes
offset += 4;
// read height and width
videoStream.Width = msManager.GetSize(offset) >> 4;
videoStream.Height = msManager.GetSize(offset + 1) & 0x0FFF;
offset += 3;
// read framerate
int frameRateIndex = msManager.GetByte(offset) & 0x0F;
if (frameRateIndex > 8)
{
// Reserved
videoStream.FrameRate = 0.0d;
}
else
{
// Retrieve value from table
videoStream.FrameRate = MpegConstants.FrameRateTable[frameRateIndex];
}
// read aspectratio
int aspectRatioIndex = (msManager.GetByte(offset) & 0xF0) >> 4;
if (aspectRatioIndex <=4)
{
videoStream.AspectRatio = MpegConstants.AspectRatio[aspectRatioIndex];
}
else
{
videoStream.AspectRatio = "Unknow";
}
offset += 1;
// read BitRate
int bitRate = ((msManager.GetByte(offset) * 0x10000) +
(msManager.GetByte(offset + 1) * 0x100) +
msManager.GetByte(offset + 2) ) >> 6;
videoStream.BitRate = bitRate;
// calculate Duration
videoStream.Duration = msManager.StreamSize / ((bitRate * 400) / 8.0);
// Extract video format and chroma format
GetVideoFormat(ref msManager, offset);
return true;
}
private void ParseExtension(long offset, ref MpegStreamManager msManager)
{
offset += 4;
int ext = msManager.GetByte(offset) >> 4;
if (ext == 1)
{
videoStream.Version = 2;
videoStream.VideoFormat = (msManager.GetByte(offset + 1) & 0x06) >> 1;
}
else if (ext == 2)
{
videoStream.VideoFormat = (msManager.GetByte(offset) & 0x0E) >> 1;
}
}
private bool ParseAudioStream(ref MpegStreamManager msManager, long offset)
{
if (Convert.ToBoolean((msManager.GetByte(offset + 1) & 0x08)))
{
audioStream.Version = 1.0d;
}
else
{
audioStream.Version = 2.0d;
}
audioStream.Layer = (msManager.GetByte(offset + 1) & 0x06) >> 1;
if (audioStream.Layer < 1 || audioStream.Layer > 3)
{
return false;
}
audioStream.Protected = Convert.ToBoolean(msManager.GetByte(offset + 1) & 0x01);
int bitrateIndex = msManager.GetByte(offset + 2) >> 4;
int samplingIndex = (msManager.GetByte(offset + 2) & 0x0F) >> 2;
if (samplingIndex >= 3 || bitrateIndex == 15)
{
return false;
}
audioStream.BitRate = MpegConstants.BitRateIndex[(int)audioStream.Version -1,
audioStream.Layer -1,
bitrateIndex];
audioStream.ByteRate = (float)((audioStream.BitRate * 1000) / 8.0d);
audioStream.SamplingRate =
MpegConstants.SamplingIndex[(int)audioStream.Version - 1, samplingIndex];
if (audioStream.BitRate <= 0 ||
audioStream.ByteRate <= 0 ||
audioStream.SamplingRate <= 0)
{
return false;
}
if (Convert.ToBoolean(msManager.GetByte(offset + 2) & 0x02))
{
audioStream.Padding = true;
}
else
{
audioStream.Padding = false;
}
audioStream.ModeCode = msManager.GetByte(offset + 3) >> 6;
// int modeExt = (msManager.GetByte(offset + 3) >> 4) & 0x03;
if (Convert.ToBoolean(msManager.GetByte(offset + 3) & 0x08))
{
audioStream.Copyright = true;
}
else
{
audioStream.Copyright = false;
}
if (Convert.ToBoolean(msManager.GetByte(offset + 3) & 0x04))
{
audioStream.Original = true;
}
else
{
audioStream.Original = false;
}
audioStream.EmphasisIndex = msManager.GetByte(offset + 3) & 0x03;
if (audioStream.Version == 1)
{
if (audioStream.Layer == 1)
{
audioStream.FrameLength =
((48000 * audioStream.BitRate) / audioStream.SamplingRate)
+ 4 * Convert.ToInt32(audioStream.Padding);
}
else
{
audioStream.FrameLength =
((144000 * audioStream.BitRate) / audioStream.SamplingRate)
+ Convert.ToInt32(audioStream.Padding);
}
}
else if (audioStream.Version == 2)
{
if (audioStream.Layer == 1)
{
audioStream.FrameLength =
((24000 * audioStream.BitRate) / audioStream.SamplingRate)
+ 4 * Convert.ToInt32(audioStream.Padding);
}
else
{
audioStream.FrameLength =
((72000 * audioStream.BitRate) / audioStream.SamplingRate)
+ Convert.ToInt32(audioStream.Padding);
}
}
else
{
return false;
}
if (audioStream.Protected)
{
// frame length sometimes gets offset by +- 2,
// got to find out why its happening,
// most likely its the protection switch (see above)
audioStream.FrameLength += 2;
}
audioStream.Duration = ((msManager.StreamSize * 1.0d) / audioStream.BitRate) * 0.008d;
return true;
}