static void writeParameters(this EncodedBuffer buffer, byte[] source, string what)
{
var span = buffer.span;
int pos = EmulationPrevention.writeStartCode4(span, 0);
// pos = EmulationPrevention.writeBytes( span, source.AsSpan(), pos );
source.AsSpan().CopyTo(span.Slice(pos));
pos += source.Length;
buffer.setLength(pos);
Logger.logVerbose("Wrote {0} into buffer #{1}; took {2} bytes including start code", what, buffer.index, pos);
}
/* protected override int writeFrame( EncodedBuffer destBuffer, int cb )
* {
* // Read the complete sample
* Span<byte> dest = destBuffer.span;
* stream.Read( dest.Slice( 0, cb ) );
*
* // Produce NALU start codes.
* for( int offset = 0; offset < cb; )
* {
* int naluLength = ( dest[ offset ] << 16 ) | ( dest[ offset + 1 ] << 8 ) | dest[ offset + 2 ];
*
* dest[ offset ] = 0;
* dest[ offset + 1 ] = 0;
* dest[ offset + 2 ] = 1;
*
* offset += ( naluLength + 3 );
* }
* return cb;
* } */
protected override int writeNalu(EncodedBuffer destBuffer, out eNaluAction result, out eNaluType type)
{
Span <byte> naluLength = stackalloc byte[4];
naluLength[0] = 0;
stream.read(naluLength.Slice(1));
int cbNalu = BitConverter.ToInt32(naluLength).endian();
Span <byte> dest = destBuffer.span;
// Write NALU start code to mapped memory
EmulationPrevention.writeStartCode4(dest, 0);
// Read NALU payload from file into mapped memory
Span <byte> naluPayload = dest.Slice(4, cbNalu);
stream.read(naluPayload);
destBuffer.setLength(cbNalu + 4);
type = setBufferMetadata(destBuffer, naluPayload, out result);
return(cbNalu + 3);
}
eNaluAction iVideoTrackReader.writeNextNalu(EncodedBuffer dest)
{
if (EOF)
{
return(eNaluAction.EOF);
}
int naluLength;
Span <byte> naluPayload;
lock (clusters.syncRoot)
{
// Seek to the blob
seek(ref readerState);
// Read 4-bytes NALU length. Unlike mpeg4, MKV header never says it's 4 bytes, i.e. just guessing here.
Span <byte> naluLengthSpan = stackalloc byte[4];
read(ref readerState, naluLengthSpan);
naluLength = BinaryPrimitives.ReadInt32BigEndian(naluLengthSpan);
Debug.Assert(readerState.bytesLeft >= naluLength);
// Write NALU start code to mapped memory
EmulationPrevention.writeStartCode4(dest.span, 0);
// Write the payload
naluPayload = dest.span.Slice(4, naluLength);
read(ref readerState, naluPayload);
}
dest.setLength(naluLength + 4);
// Parse the payload. The shared memory mapped by the driver is both readable and writeable.
eNaluAction act = setBufferMetadata(dest, naluPayload);
if (readerState.bytesLeft <= 0)
{
advance();
}
return(act);
}
