public unsafe AudioMetadata ReadMetadata(Stream stream)
{
OggStream?oggStream = null;
#if NETSTANDARD2_0
var buffer = ArrayPool <byte> .Shared.Rent(4096);
#else
Span <byte> buffer = stackalloc byte[4096];
#endif
try
{
using (var sync = new OggSync())
{
OggPage page;
do
{
// Read from the buffer into a page
while (!sync.PageOut(out page))
{
#if NETSTANDARD2_0
var bytesRead = stream.Read(buffer, 0, buffer.Length);
#else
var bytesRead = stream.Read(buffer);
#endif
if (bytesRead == 0)
{
throw new AudioInvalidException("No Ogg stream was found.");
}
var nativeBuffer = new Span <byte>(sync.Buffer(bytesRead).ToPointer(), bytesRead);
#if NETSTANDARD2_0
buffer.AsSpan().Slice(0, bytesRead).CopyTo(nativeBuffer);
#else
buffer.Slice(0, bytesRead).CopyTo(nativeBuffer);
#endif
sync.Wrote(bytesRead);
}
oggStream ??= new(SafeNativeMethods.OggPageSerialNo(page));
oggStream.PageIn(page);
while (oggStream.PacketOut(out var packet))
{
if (packet.PacketNumber == 1)
{
return(new CommentHeaderToMetadataAdapter(packet));
}
}
} while (!SafeNativeMethods.OggPageEos(page));
throw new AudioInvalidException("The end of the Ogg stream was reached without finding a header.");
}
}
finally
{
#if NETSTANDARD2_0
ArrayPool <byte> .Shared.Return(buffer);
#endif
oggStream?.Dispose();
}
}
public unsafe void WriteMetadata(Stream stream, AudioMetadata metadata, SettingDictionary settings)
{
using (var tempStream = new TempFileStream())
{
OggStream inputOggStream = null;
OggStream outputOggStream = null;
#if NETSTANDARD2_0
var buffer = ArrayPool <byte> .Shared.Rent(4096);
#else
Span <byte> buffer = stackalloc byte[4096];
#endif
try
{
using (var sync = new OggSync())
{
var headerWritten = false;
OggPage page;
var pagesWritten = 0u;
do
{
// Read from the buffer into a page
while (!sync.PageOut(out page))
{
#if NETSTANDARD2_0
var bytesRead = stream.Read(buffer, 0, buffer.Length);
#else
var bytesRead = stream.Read(buffer);
#endif
if (bytesRead == 0)
{
throw new AudioInvalidException("No Ogg stream was found.");
}
var nativeBuffer = new Span <byte>(sync.Buffer(bytesRead).ToPointer(), bytesRead);
#if NETSTANDARD2_0
buffer.AsSpan().Slice(0, bytesRead).CopyTo(nativeBuffer);
#else
buffer.Slice(0, bytesRead).CopyTo(nativeBuffer);
#endif
sync.Wrote(bytesRead);
}
if (inputOggStream == null)
{
inputOggStream = new OggStream(SafeNativeMethods.OggPageSerialNo(page));
}
if (outputOggStream == null)
{
outputOggStream = new OggStream(inputOggStream.SerialNumber);
}
// Write new header page(s) using a modified comment packet
if (!headerWritten)
{
inputOggStream.PageIn(page);
while (inputOggStream.PacketOut(out var packet))
{
switch (packet.PacketNumber)
{
case 0:
outputOggStream.PacketIn(packet);
break;
// Substitute the new comment packet
case 1:
using (var adapter = new MetadataToOpusCommentAdapter(metadata))
{
adapter.HeaderOut(out var commentPacket);
outputOggStream.PacketIn(commentPacket);
}
headerWritten = true;
break;
default:
throw new AudioInvalidException("Missing header packet.");
}
}
// Flush at the end of each header
while (outputOggStream.Flush(out var outPage))
{
WritePage(outPage, tempStream);
pagesWritten++;
}
}
else
{
// Copy the existing data pages verbatim, with updated sequence numbers
UpdateSequenceNumber(ref page, pagesWritten);
WritePage(page, tempStream);
pagesWritten++;
}
} while (!SafeNativeMethods.OggPageEos(page));
// Once the end of the input is reached, overwrite the original file and return
stream.Position = 0;
stream.SetLength(tempStream.Length);
tempStream.Position = 0;
tempStream.CopyTo(stream);
}
}
finally
{
#if NETSTANDARD2_0
ArrayPool <byte> .Shared.Return(buffer);
#endif
inputOggStream?.Dispose();
outputOggStream?.Dispose();
}
}
}