decoder/flac: refactor flac_convert() to class FlacPcmImport

src/decoder/plugins/FlacCommon.cxx

@@ -24,33 +24,10 @@
 #include "config.h"
 #include "FlacCommon.hxx"
 #include "FlacMetadata.hxx"
-#include "FlacPcm.hxx"
-#include "FlacDomain.hxx"
-#include "CheckAudioFormat.hxx"
 #include "util/Error.hxx"
+#include "util/ConstBuffer.hxx"
 #include "Log.hxx"
 
-static SampleFormat
-flac_sample_format(unsigned bits_per_sample)
-{
-	switch (bits_per_sample) {
-	case 8:
-		return SampleFormat::S8;
-
-	case 16:
-		return SampleFormat::S16;
-
-	case 24:
-		return SampleFormat::S24_P32;
-
-	case 32:
-		return SampleFormat::S32;
-
-	default:
-		return SampleFormat::UNDEFINED;
-	}
-}
-
 bool
 FlacDecoder::Initialize(unsigned sample_rate, unsigned bits_per_sample,
 			unsigned channels, FLAC__uint64 total_frames)
@@ -58,25 +35,15 @@ FlacDecoder::Initialize(unsigned sample_rate, unsigned bits_per_sample,
 	assert(!initialized);
 	assert(!unsupported);
 
-	auto sample_format = flac_sample_format(bits_per_sample);
-	if (sample_format == SampleFormat::UNDEFINED) {
-		FormatWarning(flac_domain, "Unsupported FLAC bit depth: %u",
-			      bits_per_sample);
-		unsupported = true;
-		return false;
-	}
-
 	::Error error;
-	if (!audio_format_init_checked(audio_format,
-				       sample_rate,
-				       sample_format,
-				       channels, error)) {
+	if (!pcm_import.Open(sample_rate, bits_per_sample,
+			     channels, error)) {
 		LogError(error);
 		unsupported = true;
 		return false;
 	}
 
-	frame_size = audio_format.GetFrameSize();
+	const auto audio_format = pcm_import.GetAudioFormat();
 
 	const auto duration = total_frames > 0
 		? SignedSongTime::FromScale<uint64_t>(total_frames,
@@ -174,18 +141,13 @@ FlacDecoder::OnWrite(const FLAC__Frame &frame,
 	if (!initialized && !OnFirstFrame(frame.header))
 		return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
 
-	size_t buffer_size = frame.header.blocksize * frame_size;
-	void *data = buffer.Get(buffer_size);
-
-	flac_convert(data, frame.header.channels,
-		     audio_format.format, buf,
-		     frame.header.blocksize);
+	const auto data = pcm_import.Import(buf, frame.header.blocksize);
 
 	unsigned bit_rate = nbytes * 8 * frame.header.sample_rate /
 		(1000 * frame.header.blocksize);
 
 	auto cmd = decoder_data(*GetDecoder(), GetInputStream(),
-				data, buffer_size,
+				data.data, data.size,
 				bit_rate);
 	switch (cmd) {
 	case DecoderCommand::NONE:

src/decoder/plugins/FlacCommon.hxx

@@ -25,19 +25,12 @@
 #define MPD_FLAC_COMMON_HXX
 
 #include "FlacInput.hxx"
+#include "FlacPcm.hxx"
 #include "../DecoderAPI.hxx"
-#include "pcm/PcmBuffer.hxx"
 
 #include <FLAC/stream_decoder.h>
 
 struct FlacDecoder : public FlacInput {
-	PcmBuffer buffer;
-
-	/**
-	 * The size of one frame in the output buffer.
-	 */
-	unsigned frame_size;
-
 	/**
 	 * Has decoder_initialized() been called yet?
 	 */
@@ -48,11 +41,7 @@ struct FlacDecoder : public FlacInput {
 	 */
 	bool unsupported = false;
 
-	/**
-	 * The validated audio format of the FLAC file.  This
-	 * attribute is defined if "initialized" is true.
-	 */
-	AudioFormat audio_format;
+	FlacPcmImport pcm_import;
 
 	/**
 	 * End of last frame's position within the stream.  This is
@@ -62,7 +51,6 @@ struct FlacDecoder : public FlacInput {
 
 	Tag tag;
 
-
 	FlacDecoder(Decoder &_decoder, InputStream &_input_stream)
 		:FlacInput(_input_stream, &_decoder) {}
 

src/decoder/plugins/FlacPcm.cxx

@@ -19,9 +19,54 @@
 
 #include "config.h"
 #include "FlacPcm.hxx"
+#include "FlacDomain.hxx"
+#include "CheckAudioFormat.hxx"
+#include "util/Error.hxx"
+#include "util/ConstBuffer.hxx"
 
 #include <assert.h>
 
+static SampleFormat
+flac_sample_format(unsigned bits_per_sample)
+{
+	switch (bits_per_sample) {
+	case 8:
+		return SampleFormat::S8;
+
+	case 16:
+		return SampleFormat::S16;
+
+	case 24:
+		return SampleFormat::S24_P32;
+
+	case 32:
+		return SampleFormat::S32;
+
+	default:
+		return SampleFormat::UNDEFINED;
+	}
+}
+
+bool
+FlacPcmImport::Open(unsigned sample_rate, unsigned bits_per_sample,
+		    unsigned channels, Error &error)
+{
+	auto sample_format = flac_sample_format(bits_per_sample);
+	if (sample_format == SampleFormat::UNDEFINED) {
+		error.Format(flac_domain, "Unsupported FLAC bit depth: %u",
+			     bits_per_sample);
+		return false;
+	}
+
+	if (!audio_format_init_checked(audio_format,
+				       sample_rate,
+				       sample_format,
+				       channels, error))
+		return false;
+
+	return true;
+}
+
 template<typename T>
 static void
 FlacImportStereo(T *dest, const FLAC__int32 *const src[], size_t n_frames)
@@ -53,30 +98,41 @@ FlacImport(T *dest, const FLAC__int32 *const src[], size_t n_frames,
 		FlacImportAny(dest, src, n_frames, n_channels);
 }
 
-void
-flac_convert(void *dest,
-	     unsigned int num_channels, SampleFormat sample_format,
-	     const FLAC__int32 *const buf[],
-	     size_t n_frames)
+template<typename T>
+static ConstBuffer<void>
+FlacImport(PcmBuffer &buffer, const FLAC__int32 *const src[], size_t n_frames,
+	   unsigned n_channels)
+{
+	size_t n_samples = n_frames * n_channels;
+	size_t dest_size = n_samples * sizeof(T);
+	T *dest = (T *)buffer.Get(dest_size);
+	FlacImport(dest, src, n_frames, n_channels);
+	return {dest, dest_size};
+}
+
+ConstBuffer<void>
+FlacPcmImport::Import(const FLAC__int32 *const src[], size_t n_frames)
 {
-	switch (sample_format) {
+	switch (audio_format.format) {
 	case SampleFormat::S16:
-		FlacImport((int16_t *)dest, buf, n_frames, num_channels);
-		break;
+		return FlacImport<int16_t>(buffer, src, n_frames,
+					   audio_format.channels);
 
 	case SampleFormat::S24_P32:
 	case SampleFormat::S32:
-		FlacImport((int32_t *)dest, buf, n_frames, num_channels);
-		break;
+		return FlacImport<int32_t>(buffer, src, n_frames,
+					   audio_format.channels);
 
 	case SampleFormat::S8:
-		FlacImport((int8_t *)dest, buf, n_frames, num_channels);
-		break;
+		return FlacImport<int8_t>(buffer, src, n_frames,
+					  audio_format.channels);
 
 	case SampleFormat::FLOAT:
 	case SampleFormat::DSD:
 	case SampleFormat::UNDEFINED:
-		assert(false);
-		gcc_unreachable();
+		break;
 	}
+
+	assert(false);
+	gcc_unreachable();
 }

src/decoder/plugins/FlacPcm.hxx

@@ -20,16 +20,37 @@
 #ifndef MPD_FLAC_PCM_HXX
 #define MPD_FLAC_PCM_HXX
 
+#include "check.h"
+#include "pcm/PcmBuffer.hxx"
 #include "AudioFormat.hxx"
 
 #include <FLAC/ordinals.h>
 
-#include <stddef.h>
+class Error;
+template<typename T> struct ConstBuffer;
 
-void
-flac_convert(void *dest,
-	     unsigned int num_channels, SampleFormat sample_format,
-	     const FLAC__int32 *const buf[],
-	     size_t n_frames);
+/**
+ * This class imports libFLAC PCM data into a PCM format supported by
+ * MPD.
+ */
+class FlacPcmImport {
+	PcmBuffer buffer;
+
+	AudioFormat audio_format;
+
+public:
+	/**
+	 * @return false on error
+	 */
+	bool Open(unsigned sample_rate, unsigned bits_per_sample,
+		  unsigned channels, Error &error);
+
+	const AudioFormat &GetAudioFormat() const {
+		return audio_format;
+	}
+
+	ConstBuffer<void> Import(const FLAC__int32 *const src[],
+				 size_t n_frames);
+};
 
 #endif