/// <summary>
/// Construct Mpeg file representation from stream.
/// </summary>
/// <param name="stream">The input stream which contains Mpeg data.</param>
public MpegFile(Stream stream, bool leaveOpen)
{
_stream = stream;
_leaveOpen = leaveOpen;
_reader = new Decoder.MpegStreamReader(_stream);
_decoder = new MpegFrameDecoder();
}
public int Read(MpegStreamReader reader, long offset, Span <byte> destination)
{
int count = destination.Length;
int startIdx = EnsureFilled(reader, offset, ref count);
Data.AsSpan(startIdx, count).CopyTo(destination);
return(count);
}
void Init(System.IO.Stream stream, bool closeStream)
{
_stream = stream;
_closeStream = closeStream;
_reader = new Decoder.MpegStreamReader(_stream);
_decoder = new MpegFrameDecoder();
}
void Init(System.IO.Stream stream, bool closeStream)
{
_stream = stream;
_closeStream = closeStream;
_reader = new Decoder.MpegStreamReader(_stream);
_decoder = new MpegFrameDecoder();
}
public int Read(MpegStreamReader reader, long offset, byte[] buffer, int index, int count)
{
lock (_localLock)
{
var startIdx = EnsureFilled(reader, offset, ref count);
Buffer.BlockCopy(Data, startIdx, buffer, index, count);
}
return(count);
}
public int ReadByte(MpegStreamReader reader, long offset)
{
int count = 1;
int startIdx = EnsureFilled(reader, offset, ref count);
if (count == 1)
{
return(Data[startIdx]);
}
return(-1);
}
public int ReadByte(MpegStreamReader reader, long offset)
{
lock (_localLock)
{
var count = 1;
var startIdx = EnsureFilled(reader, offset, ref count);
if (count == 1)
{
return(Data[startIdx]);
}
}
return(-1);
}
internal bool Validate(long offset, MpegStreamReader reader)
{
Offset = offset;
_reader = reader;
var len = Validate();
if (len > 0)
{
Length = len;
return(true);
}
return(false);
}
public bool ValidateFrameHeader(long offset, MpegStreamReader reader)
{
_reader = reader ?? throw new ArgumentNullException(nameof(reader));
Offset = offset;
int length = ValidateFrameHeader();
if (length > 0)
{
Length = length;
return(true);
}
return(false);
}
internal bool Validate(long offset, MpegStreamReader reader)
{
Offset = offset;
_reader = reader;
var len = Validate();
if (len > 0)
{
Length = len;
return true;
}
return false;
}
int EnsureFilled(MpegStreamReader reader, long offset, ref int count)
{
// if the offset & count are inside our buffer's range, just return the appropriate index
var startIdx = (int)(offset - BaseOffset);
int endIdx = startIdx + count;
if (startIdx < 0 || endIdx > End)
{
int readStart = 0, readCount = 0, moveCount = 0;
long readOffset = 0;
#region Decision-Making
if (startIdx < 0)
{
// if we can't seek, there's nothing we can do
if (!reader._source.CanSeek)
{
throw new InvalidOperationException("Cannot seek backwards on a forward-only stream!");
}
// if there's data in the buffer, try to keep it (up to doubling the buffer size)
if (End > 0)
{
// if doubling the buffer would push it past the max size, don't check it
if ((startIdx + Data.Length > 0) || (Data.Length * 2 <= 16384 && startIdx + Data.Length * 2 > 0))
{
endIdx = End;
}
}
// we know we'll have to start reading here
readOffset = offset;
// if the end of the request is before the start of our buffer...
if (endIdx < 0)
{
// ... just truncate and move on
Truncate();
// set up our read parameters
BaseOffset = offset;
startIdx = 0;
endIdx = count;
// how much do we need to read?
readCount = count;
}
else // i.e., endIdx >= 0
{
// we have overlap with existing data... save as much as possible
moveCount = -endIdx;
readCount = -startIdx;
}
}
else // i.e., startIdx >= 0
{
// we only get to here if at least one byte of the request is past the end of the read data
// start with the simplest scenario and work our way up
// 1) We just need to fill the buffer a bit more
if (endIdx < Data.Length)
{
readCount = endIdx - End;
readStart = End;
readOffset = BaseOffset + readStart;
}
// 2) We need to discard some bytes, then fill the buffer
else if (endIdx - DiscardCount < Data.Length)
{
moveCount = DiscardCount;
readStart = End;
readCount = endIdx - readStart;
readOffset = BaseOffset + readStart;
}
// 3) We need to expand the buffer to hold all the existing & requested data
else if (Data.Length * 2 <= 16384)
{
// by definition, we discard
moveCount = DiscardCount;
readStart = End;
readCount = endIdx - End;
readOffset = BaseOffset + readStart;
}
// 4) We have to throw away some data that hasn't been discarded
else
{
// just truncate
Truncate();
// set up our read parameters
BaseOffset = offset;
readOffset = offset;
startIdx = 0;
endIdx = count;
// how much do we have to read?
readCount = count;
}
}
#endregion
#region Buffer Resizing & Data Moving
if (endIdx - moveCount > Data.Length || readStart + readCount - moveCount > Data.Length)
{
var newSize = Data.Length * 2;
while (newSize < endIdx - moveCount)
{
newSize *= 2;
}
var newBuf = new byte[newSize];
if (moveCount < 0)
{
// reverse copy
Buffer.BlockCopy(Data, 0, newBuf, -moveCount, End + moveCount);
DiscardCount = 0;
}
else
{
// forward or neutral copy
Buffer.BlockCopy(Data, moveCount, newBuf, 0, End - moveCount);
DiscardCount -= moveCount;
}
Data = newBuf;
}
else if (moveCount != 0)
{
if (moveCount > 0)
{
// forward move
Buffer.BlockCopy(Data, moveCount, Data, 0, End - moveCount);
DiscardCount -= moveCount;
}
else
{
// backward move
for (int i = 0, srcIdx = Data.Length - 1, destIdx = Data.Length - 1 - moveCount; i < moveCount; i++, srcIdx--, destIdx--)
{
Data[destIdx] = Data[srcIdx];
}
DiscardCount = 0;
}
}
BaseOffset += moveCount;
readStart -= moveCount;
startIdx -= moveCount;
endIdx -= moveCount;
End -= moveCount;
#endregion
#region Buffer Filling
lock (reader._readLock)
{
if (readCount > 0 && reader._source.Position != readOffset && readOffset < reader._eofOffset)
{
if (reader._canSeek)
{
try
{
reader._source.Position = readOffset;
}
catch (EndOfStreamException)
{
reader._eofOffset = reader._source.Length;
readCount = 0;
}
}
else
{
// ugh, gotta read bytes until we've reached the desired offset
var seekCount = readOffset - reader._source.Position;
while (--seekCount >= 0)
{
if (reader._source.ReadByte() == -1)
{
reader._eofOffset = reader._source.Position;
readCount = 0;
break;
}
}
}
}
while (readCount > 0 && readOffset < reader._eofOffset)
{
var temp = reader._source.Read(Data, readStart, readCount);
if (temp == 0)
{
break;
}
readStart += temp;
readOffset += temp;
readCount -= temp;
}
if (readStart > End)
{
End = readStart;
}
if (End < endIdx)
{
// we didn't get a full read...
count = Math.Max(0, End - startIdx);
}
// NB: if desired, switch to "minimal reads" by commenting-out this clause
else if (End < Data.Length)
{
// try to finish filling the buffer
var temp = reader._source.Read(Data, End, Data.Length - End);
End += temp;
}
}
#endregion
}
return(startIdx);
}
int EnsureFilled(MpegStreamReader reader, long offset, ref int count)
{
// if the offset & count are inside our buffer's range, just return the appropriate index
var startIdx = (int)(offset - BaseOffset);
int endIdx = startIdx + count;
if (startIdx < 0 || endIdx > End)
{
int readStart = 0, readCount = 0, moveCount = 0;
long readOffset = 0;
#region Decision-Making
if (startIdx < 0)
{
// if we can't seek, there's nothing we can do
if (!reader._source.CanSeek) throw new InvalidOperationException("Cannot seek backwards on a forward-only stream!");
// if there's data in the buffer, try to keep it (up to doubling the buffer size)
if (End > 0)
{
// if doubling the buffer would push it past the max size, don't check it
if ((startIdx + Data.Length > 0) || (Data.Length * 2 <= 16384 && startIdx + Data.Length * 2 > 0))
{
endIdx = End;
}
}
// we know we'll have to start reading here
readOffset = offset;
// if the end of the request is before the start of our buffer...
if (endIdx < 0)
{
// ... just truncate and move on
Truncate();
// set up our read parameters
BaseOffset = offset;
startIdx = 0;
endIdx = count;
// how much do we need to read?
readCount = count;
}
else // i.e., endIdx >= 0
{
// we have overlap with existing data... save as much as possible
moveCount = -endIdx;
readCount = -startIdx;
}
}
else // i.e., startIdx >= 0
{
// we only get to here if at least one byte of the request is past the end of the read data
// start with the simplest scenario and work our way up
// 1) We just need to fill the buffer a bit more
if (endIdx < Data.Length)
{
readCount = endIdx - End;
readStart = End;
readOffset = BaseOffset + readStart;
}
// 2) We need to discard some bytes, then fill the buffer
else if (endIdx - DiscardCount < Data.Length)
{
moveCount = DiscardCount;
readStart = End;
readCount = endIdx - readStart;
readOffset = BaseOffset + readStart;
}
// 3) We need to expand the buffer to hold all the existing & requested data
else if (Data.Length * 2 <= 16384)
{
// by definition, we discard
moveCount = DiscardCount;
readStart = End;
readCount = endIdx - End;
readOffset = BaseOffset + readStart;
}
// 4) We have to throw away some data that hasn't been discarded
else
{
// just truncate
Truncate();
// set up our read parameters
BaseOffset = offset;
readOffset = offset;
startIdx = 0;
endIdx = count;
// how much do we have to read?
readCount = count;
}
}
#endregion
#region Buffer Resizing & Data Moving
if (endIdx - moveCount > Data.Length || readStart + readCount - moveCount > Data.Length)
{
var newSize = Data.Length * 2;
while (newSize < endIdx - moveCount)
{
newSize *= 2;
}
var newBuf = new byte[newSize];
if (moveCount < 0)
{
// reverse copy
Buffer.BlockCopy(Data, 0, newBuf, -moveCount, End + moveCount);
DiscardCount = 0;
}
else
{
// forward or neutral copy
Buffer.BlockCopy(Data, moveCount, newBuf, 0, End - moveCount);
DiscardCount -= moveCount;
}
Data = newBuf;
}
else if (moveCount != 0)
{
if (moveCount > 0)
{
// forward move
Buffer.BlockCopy(Data, moveCount, Data, 0, End - moveCount);
DiscardCount -= moveCount;
}
else
{
// backward move
for (int i = 0, srcIdx = Data.Length - 1, destIdx = Data.Length - 1 - moveCount; i < moveCount; i++, srcIdx--, destIdx--)
{
Data[destIdx] = Data[srcIdx];
}
DiscardCount = 0;
}
}
BaseOffset += moveCount;
readStart -= moveCount;
startIdx -= moveCount;
endIdx -= moveCount;
End -= moveCount;
#endregion
#region Buffer Filling
lock (reader._readLock)
{
if (readCount > 0 && reader._source.Position != readOffset && readOffset < reader._eofOffset)
{
if (reader._canSeek)
{
try
{
reader._source.Position = readOffset;
}
catch (EndOfStreamException)
{
reader._eofOffset = reader._source.Length;
readCount = 0;
}
}
else
{
// ugh, gotta read bytes until we've reached the desired offset
var seekCount = readOffset - reader._source.Position;
while (--seekCount >= 0)
{
if (reader._source.ReadByte() == -1)
{
reader._eofOffset = reader._source.Position;
readCount = 0;
break;
}
}
}
}
while (readCount > 0 && readOffset < reader._eofOffset)
{
var temp = reader._source.Read(Data, readStart, readCount);
if (temp == 0)
{
break;
}
readStart += temp;
readOffset += temp;
readCount -= temp;
}
if (readStart > End)
{
End = readStart;
}
if (End < endIdx)
{
// we didn't get a full read...
count = Math.Max(0, End - startIdx);
}
// NB: if desired, switch to "minimal reads" by commenting-out this clause
else if (End < Data.Length)
{
// try to finish filling the buffer
var temp = reader._source.Read(Data, End, Data.Length - End);
End += temp;
}
}
#endregion
}
return startIdx;
}
public int ReadByte(MpegStreamReader reader, long offset)
{
lock (_localLock)
{
var count = 1;
var startIdx = EnsureFilled(reader, offset, ref count);
if (count == 1)
{
return Data[startIdx];
}
}
return -1;
}
public int Read(MpegStreamReader reader, long offset, byte[] buffer, int index, int count)
{
lock (_localLock)
{
var startIdx = EnsureFilled(reader, offset, ref count);
Buffer.BlockCopy(Data, startIdx, buffer, index, count);
}
return count;
}
