public void Initialize(Stream stream, AudioInfo info, AudioMetadata metadata, SettingDictionary settings)
{
var gain = 0;
if (settings.TryGetValue("ApplyGain", out string applyGain))
{
var scale = applyGain.Equals("Track", StringComparison.OrdinalIgnoreCase)
? CalculateScale(metadata.TrackGain, metadata.TrackPeak)
: CalculateScale(metadata.AlbumGain, metadata.AlbumPeak);
// Adjust the metadata so that it remains valid
metadata.TrackGain = CalculateGain(metadata.TrackGain, scale);
metadata.AlbumGain = CalculateGain(metadata.AlbumGain, scale);
gain = (int)Math.Round(Math.Log10(scale) * 5120);
}
_comments = new MetadataToOpusCommentAdapter(metadata);
_encoder = new Encoder(stream, info.SampleRate, info.Channels, (int)info.PlayLength.TotalSeconds,
_comments.Handle);
if (info.BitsPerSample > 0)
{
_encoder.SetLsbDepth(Math.Min(Math.Max(info.BitsPerSample, 8), 24));
}
_encoder.SetHeaderGain(gain);
if (!settings.TryGetValue("SerialNumber", out int serialNumber))
{
serialNumber = new Random().Next();
}
_encoder.SetSerialNumber(serialNumber);
// Default to full VBR
if (settings.TryGetValue("ControlMode", out string vbrMode))
{
switch (vbrMode)
{
case "Variable":
_encoder.SetVbrConstraint(false);
break;
// 'Constrained' is the libopusenc default
case "Constant":
_encoder.SetVbr(false);
break;
}
}
else
{
_encoder.SetVbrConstraint(false);
}
if (settings.TryGetValue("BitRate", out int bitRate))
{
_encoder.SetBitRate(bitRate);
}
if (settings.TryGetValue("SignalType", out string signalType))
{
_encoder.SetSignal(signalType.Equals("Speech", StringComparison.OrdinalIgnoreCase)
? SignalType.Speech
: SignalType.Music);
}
else
{
_encoder.SetSignal(SignalType.Music);
}
}
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();
}
}
}