public ReplayGainAdaptiveAudioStream(AudioStream baseAudioStream, Decibel target) : base(baseAudioStream.ParentData)
{
_currentGain = new Decibel(0);
_baseAudioStream = baseAudioStream;
_target = target;
_ebuR128State = new EbuR128State(baseAudioStream.Format, EbuR128Modes.ShortTerm);
switch (baseAudioStream.Format.DataFormat.BytesPerSample)
{
case 2:
_transformFunc = TransformShort;
break;
case 4 when baseAudioStream.Format.DataFormat.NumberFormat == NumberFormat.Signed:
_transformFunc = TransformInt;
break;
case 4 when baseAudioStream.Format.DataFormat.NumberFormat == NumberFormat.FloatingPoint:
_transformFunc = TransformFloat;
break;
case 8:
_transformFunc = TransformDouble;
break;
}
}
public AudioStream TransformAudioStream(AudioStream stream)
{
var db = new Decibel(0);
var albumGainString = stream.ParentData.Metadata.FirstOrDefault(x =>
x.Key.Equals("REPLAYGAIN_ALBUM_GAIN", StringComparison.InvariantCultureIgnoreCase)).Value;
var trackGainString = stream.ParentData.Metadata.FirstOrDefault(x =>
x.Key.Equals("REPLAYGAIN_TRACK_GAIN", StringComparison.InvariantCultureIgnoreCase)).Value;
if (albumGainString != null)
{
db = new Decibel(double.Parse(Regex.Match(albumGainString, DB_REGEX).Groups["value"].Value));
}
if (trackGainString != null)
{
db = new Decibel(double.Parse(Regex.Match(trackGainString, DB_REGEX).Groups["value"].Value));
}
var ratio = db.GetAmplitudeRatio();
return(new FFmpegFilterAudioStream(stream,
new AudioFormat(stream.Format.SampleRate, stream.Format.Channels,
new AudioDataFormat(NumberFormat.FloatingPoint, !BitConverter.IsLittleEndian, 4)),
new FilterConfiguration("volume", new Dictionary <string, string>
{
["volume"] = ratio.ToString(CultureInfo.InvariantCulture)
})));
}
public override int Read(byte[] buffer, int offset, int count)
{
var len = _baseAudioStream.Read(buffer, offset, count);
_ebuR128State.AddFrames(buffer, offset, len);
_currentGain = new Decibel(Math.Min(MAX_DB, _currentGain.Value * ALPHA + (1 - ALPHA) * (_target.Value - _ebuR128State.GetLoudness())));
// Console.WriteLine("Current Gain: {0} dB", _currentGain.Value);
_transformFunc(buffer, offset, len, _currentGain.GetAmplitudeRatio());
return(len);
}
