public AudioEngine(string audioDevice = null, AudioDriver driver = AudioDriver.Default, int sampleRate = 44100, int bufferLength = 1024, ResampleQuality resampleQuality = ResampleQuality.High)
{
this.resampleQuality = resampleQuality;
SDL.SDL_InitSubSystem(SDL.SDL_INIT_AUDIO);
audioCallback = AudioCallback;
SDL.SDL_AudioSpec desired = new SDL.SDL_AudioSpec()
{
freq = sampleRate,
format = SDL.AUDIO_S16,
channels = 2,
samples = (ushort)bufferLength,
callback = audioCallback,
};
if (driver == AudioDriver.File)
{
audioSpec = desired;
audioDriver = driver;
}
else
{
string[] audioDrivers = new string[SDL.SDL_GetNumAudioDrivers()];
for (int i = 0; i < audioDrivers.Length; i++)
{
audioDrivers[i] = SDL.SDL_GetAudioDriver(i);
}
string driverName = audioDrivers[0];
string driverFallbackName = audioDrivers.Length > 1 ? audioDrivers[1] : null;
if (driver != AudioDriver.Default)
{
driverName = driver.ToString();
}
int init = SDL.SDL_AudioInit(driverName.ToLower());
if (init != 0 && driverName == AudioDriver.XAudio2.ToString().ToLower() && driverFallbackName != null)
{
// supplied SDL.dll does not support XAudio2, fallback to next driver
driverName = driverFallbackName;
init = SDL.SDL_AudioInit(driverName.ToLower());
}
if (init != 0)
{
throw new ApplicationException("Failed to initialize audio driver " + driverName + ": " + SDL.SDL_GetError());
}
Enum.TryParse(driverName, true, out audioDriver);
if (audioDevice == null)
{
string[] audioDevices = new string[SDL.SDL_GetNumAudioDevices(0)];
for (int i = 0; i < audioDevices.Length; i++)
{
audioDevices[i] = SDL.SDL_GetAudioDeviceName(i, 0);
}
audioDevice = audioDevices.Length > 0 ? audioDevices[0] : null;
}
outputDevice = SDL.SDL_OpenAudioDevice(audioDevice, 0, ref desired, out audioSpec, 0);
if (outputDevice == 0)
{
throw new ApplicationException("Failed to open audio device " + audioDevice + ": " + SDL.SDL_GetError());
}
}
if (audioSpec.format == SDL.AUDIO_S32)
{
bytesPerSample = (uint)audioSpec.channels * 4;
}
else if (audioSpec.format == SDL.AUDIO_S16 || audioSpec.format == SDL.AUDIO_F32)
{
bytesPerSample = (uint)audioSpec.channels * 2;
}
else if (audioSpec.format == SDL.AUDIO_S8 || audioSpec.format == SDL.AUDIO_U8)
{
bytesPerSample = (uint)audioSpec.channels * 1;
}
if (audioSpec.size == 0)
{
audioSpec.size = audioSpec.samples * bytesPerSample;
}
emptyBuffer = new byte[audioSpec.size];
audioBuffer = new byte[audioSpec.size];
lastCallback = 0.0;
bufferTimer = Stopwatch.StartNew();
if (outputDevice != 0)
{
SDL.SDL_PauseAudioDevice(outputDevice, 0);
}
}
public static byte[] SoundFromFileResample(string path, int sampleRate, int channels, ushort sampleFormatSDL, ResampleQuality resampleQuality = ResampleQuality.High)
{
AVSampleFormat targetFormat2;
switch (sampleFormatSDL)
{
case SDL.AUDIO_S16:
targetFormat2 = AVSampleFormat.AV_SAMPLE_FMT_S16;
break;
case SDL.AUDIO_F32:
targetFormat2 = AVSampleFormat.AV_SAMPLE_FMT_FLT;
break;
case SDL.AUDIO_S32:
targetFormat2 = AVSampleFormat.AV_SAMPLE_FMT_S32;
break;
default:
throw new ApplicationException("Could not map SDL audio format to AVSampleFormat: " + sampleFormatSDL.ToString());
}
using (FFmpegContext ffContext = FFmpegContext.Read(path))
{
ffContext.SelectStream(AVMediaType.AVMEDIA_TYPE_AUDIO);
// setup resamplers and other format converters if needed
ffContext.ConvertToFormat(targetFormat2, sampleRate, channels, resampleQuality);
// FFmpeg only approximates stream durations but is
// usually not far from the real duration.
byte[] bytes = new byte[ffContext.audioBytesTotal];
// read all data from frames
long offset = 0;
while (ffContext.ReadFrame())
{
long frameSize = ffContext.GetFrameBufferSize();
if (offset + frameSize > bytes.Length)
{
Array.Resize(ref bytes, (int)(offset + frameSize));
}
offset += ffContext.GetFrameData(ref bytes, (int)offset);
}
return(bytes);
}
}
public void ConvertToFormat(AVSampleFormat sampleFormat, int sampleRate, int channels, ResampleQuality resampleQuality = ResampleQuality.High)
{
if (format == (int)sampleFormat &&
this.sampleRate == sampleRate &&
this.channels == channels)
{
return;
}
format = (int)sampleFormat;
this.sampleRate = sampleRate;
this.channels = channels;
int channelLayout = (int)ffmpeg.av_get_default_channel_layout(channels);
swrContext = ffmpeg.swr_alloc();
ffmpeg.av_opt_set_int(swrContext, "in_channel_layout", (int)codecContext->channel_layout, 0);
ffmpeg.av_opt_set_int(swrContext, "out_channel_layout", channelLayout, 0);
ffmpeg.av_opt_set_int(swrContext, "in_channel_count", codecContext->channels, 0);
ffmpeg.av_opt_set_int(swrContext, "out_channel_count", channels, 0);
ffmpeg.av_opt_set_int(swrContext, "in_sample_rate", codecContext->sample_rate, 0);
ffmpeg.av_opt_set_int(swrContext, "out_sample_rate", sampleRate, 0);
ffmpeg.av_opt_set_sample_fmt(swrContext, "in_sample_fmt", codecContext->sample_fmt, 0);
ffmpeg.av_opt_set_sample_fmt(swrContext, "out_sample_fmt", sampleFormat, 0);
switch (resampleQuality)
{
case ResampleQuality.Low:
ffmpeg.av_opt_set_int(swrContext, "filter_size", 0, 0);
ffmpeg.av_opt_set_int(swrContext, "phase_shift", 0, 0);
break;
case ResampleQuality.Medium:
// default ffmpeg settings
break;
case ResampleQuality.High:
ffmpeg.av_opt_set_int(swrContext, "filter_size", 128, 0);
ffmpeg.av_opt_set_double(swrContext, "cutoff", 1.0, 0);
break;
case ResampleQuality.Highest:
ffmpeg.av_opt_set_int(swrContext, "filter_size", 256, 0);
ffmpeg.av_opt_set_double(swrContext, "cutoff", 1.0, 0);
break;
}
if (ffmpeg.swr_init(swrContext) != 0)
{
throw new ApplicationException("Failed init SwrContext: " + FFmpegHelper.logLastLine);
}
}
