Add support for floating-point audio. Closes #1490.

Originally committed to SVN as r6904.

aegisub/src/audio_provider_avs.cpp

@@ -146,6 +146,7 @@ void AvisynthAudioProvider::LoadFromClip(AVSValue _clip) {
 	num_samples = vi.num_audio_samples;
 	sample_rate = vi.SamplesPerSecond();
 	bytes_per_sample = vi.BytesPerAudioSample();
+	float_samples = false;
 
 	clip = tempclip;
 }

aegisub/src/audio_provider_convert.cpp

@@ -31,6 +31,10 @@
 
 #include <libaegisub/scoped_ptr.h>
 
+#ifndef AGI_PRE
+#include <limits>
+#endif
+
 /// Base class for all wrapping converters
 class AudioProviderConverter : public AudioProvider {
 protected:
@@ -41,13 +45,14 @@ public:
 		num_samples = source->GetNumSamples();
 		sample_rate = source->GetSampleRate();
 		bytes_per_sample = source->GetBytesPerSample();
+		float_samples = source->AreSamplesFloat();
 	}
 
 	bool AreSamplesNativeEndian() const { return true; }
 	wxString GetFilename() const { return source->GetFilename(); }
 };
 
-/// Anything -> 16 bit signed machine-endian audio converter
+/// Anything integral -> 16 bit signed machine-endian audio converter
 template<class Target>
 class BitdepthConvertAudioProvider : public AudioProviderConverter {
 	int src_bytes_per_sample;
@@ -104,6 +109,40 @@ public:
 	}
 };
 
+/// Floating point -> 16 bit signed machine-endian audio converter
+template<class Source, class Target>
+class FloatConvertAudioProvider : public AudioProviderConverter {
+public:
+	FloatConvertAudioProvider(AudioProvider *src) : AudioProviderConverter(src) {
+		if (!src->AreSamplesNativeEndian())
+			throw agi::AudioProviderOpenError("Audio format converter: Float audio with non-native endianness is currently unsupported.", 0);
+		bytes_per_sample = sizeof(Target);
+		float_samples = false;
+	}
+
+	void GetAudio(void *buf, int64_t start, int64_t count) const {
+		std::vector<Source> src_buf(count * channels);
+		source->GetAudio(&src_buf[0], start, count);
+
+		Target *dest = reinterpret_cast<Target*>(buf);
+
+		for (size_t i = 0; i < static_cast<size_t>(count * channels); ++i) {
+			Source expanded;
+			if (src_buf[i] < 0)
+				expanded = static_cast<Target>(-src_buf[i] * std::numeric_limits<Target>::min());
+			else
+				expanded = static_cast<Target>(src_buf[i] * std::numeric_limits<Target>::max());
+
+			if (expanded < std::numeric_limits<Target>::min())
+				dest[i] = std::numeric_limits<Target>::min();
+			else if (expanded > std::numeric_limits<Target>::max())
+				dest[i] = std::numeric_limits<Target>::max();
+			else
+				dest[i] = static_cast<Target>(expanded);
+		}
+	}
+};
+
 /// Non-mono 16-bit signed machine-endian -> mono 16-bit signed machine endian converter
 class DownmixAudioProvider : public AudioProviderConverter {
 	int src_channels;
@@ -178,6 +217,12 @@ AudioProvider *CreateConvertAudioProvider(AudioProvider *source_provider) {
 	AudioProvider *provider = source_provider;
 
 	// Ensure 16-bit audio with proper endianness
+	if (provider->AreSamplesFloat()) {
+		if (provider->GetBytesPerSample() == sizeof(float))
+			provider = new FloatConvertAudioProvider<float, int16_t>(provider);
+		else
+			provider = new FloatConvertAudioProvider<double, int16_t>(provider);
+	}
 	if (provider->GetBytesPerSample() != 2 || !provider->AreSamplesNativeEndian())
 		provider = new BitdepthConvertAudioProvider<int16_t>(provider);
 

aegisub/src/audio_provider_dummy.cpp

@@ -44,6 +44,7 @@ DummyAudioProvider::DummyAudioProvider(unsigned long dur_ms, bool _noise) {
 	channels = 1;
 	sample_rate = 44100;
 	bytes_per_sample = 2;
+	float_samples = false;
 	num_samples = (int64_t)dur_ms * sample_rate / 1000;
 }
 

aegisub/src/audio_provider_ffmpegsource.cpp

@@ -161,13 +161,12 @@ void FFmpegSourceAudioProvider::LoadAudio(wxString filename) {
 	if (channels <= 0 || sample_rate <= 0 || num_samples <= 0)
 		throw agi::AudioProviderOpenError("sanity check failed, consult your local psychiatrist", 0);
 
-	// FIXME: use the actual sample format too?
-	// why not just bits_per_sample/8? maybe there's some oddball format with half bytes out there somewhere...
-	switch (AudioInfo.BitsPerSample) {
-		case 8:		bytes_per_sample = 1; break;
-		case 16:	bytes_per_sample = 2; break;
-		case 24:	bytes_per_sample = 3; break;
-		case 32:	bytes_per_sample = 4; break;
+	switch (AudioInfo.SampleFormat) {
+		case FFMS_FMT_U8:  bytes_per_sample = 1; float_samples = false; break;
+		case FFMS_FMT_S16: bytes_per_sample = 2; float_samples = false; break;
+		case FFMS_FMT_S32: bytes_per_sample = 4; float_samples = false; break;
+		case FFMS_FMT_FLT: bytes_per_sample = 4; float_samples = true; break;
+		case FFMS_FMT_DBL: bytes_per_sample = 8; float_samples = true; break;
 		default:
 			throw agi::AudioProviderOpenError("unknown or unsupported sample format", 0);
 	}

aegisub/src/audio_provider_hd.cpp

@@ -86,6 +86,7 @@ public:
 		channels         = src->GetChannels();
 		sample_rate      = src->GetSampleRate();
 		filename         = src->GetFilename();
+		float_samples    = src->AreSamplesFloat();
 
 		IndexPoint p = { 0, 0, num_samples };
 		index_points.push_back(p);
@@ -112,6 +113,7 @@ HDAudioProvider::HDAudioProvider(AudioProvider *src, agi::BackgroundRunner *br)
 	channels         = source->GetChannels();
 	sample_rate      = source->GetSampleRate();
 	filename         = source->GetFilename();
+	float_samples    = source->AreSamplesFloat();
 
 	diskCacheFilename = cache_path();
 

aegisub/src/audio_provider_pcm.cpp

@@ -114,6 +114,7 @@ PCMAudioProvider::PCMAudioProvider(const wxString &filename)
 
 	current_mapping = 0;
 #endif
+	float_samples = false;
 }
 
 /// @brief DOCME

aegisub/src/audio_provider_ram.cpp

@@ -78,6 +78,7 @@ RAMAudioProvider::RAMAudioProvider(AudioProvider *src, agi::BackgroundRunner *br
 	channels = source->GetChannels();
 	sample_rate = source->GetSampleRate();
 	filename = source->GetFilename();
+	float_samples = source->AreSamplesFloat();
 
 	br->Run(std::tr1::bind(&RAMAudioProvider::FillCache, this, src, std::tr1::placeholders::_1));
 }

aegisub/src/include/aegisub/audio_provider.h

@@ -52,8 +52,8 @@ protected:
 	/// DOCME
 	int channels;
 
-	/// DOCME
-	int64_t num_samples; // for one channel, ie. number of PCM frames
+	/// for one channel, ie. number of PCM frames
+	int64_t num_samples;
 
 	/// DOCME
 	int sample_rate;
@@ -61,6 +61,8 @@ protected:
 	/// DOCME
 	int bytes_per_sample;
 
+	bool float_samples;
+
 
 	/// DOCME
 	wxString filename;
@@ -76,6 +78,7 @@ public:
 	int GetSampleRate() const     { return sample_rate; }
 	int GetBytesPerSample() const { return bytes_per_sample; }
 	int GetChannels() const       { return channels; }
+	bool AreSamplesFloat() const  { return float_samples; }
 	virtual bool AreSamplesNativeEndian() const = 0;
 
 	/// @brief Does this provider benefit from external caching?