WavPipeInputStream: avoid filling sample array with zeros before read.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/rawconverter.cc

@@ -34,7 +34,7 @@ class RawConverterImpl : public RawConverter
 {
 public:
   void to_raw (const std::vector<float>& samples, std::vector<unsigned char>& bytes) AUDIOWMARK_EXTRA_OPT;
-  void from_raw (const std::vector<unsigned char>& bytes, std::vector<float>& samples) AUDIOWMARK_EXTRA_OPT;
+  void from_raw (const unsigned char *bytes, float *samples, size_t n_samples) AUDIOWMARK_EXTRA_OPT;
 };
 
 template<int BIT_DEPTH, RawFormat::Endian ENDIAN>
@@ -166,9 +166,9 @@ RawConverterImpl<BIT_DEPTH, ENDIAN, ENCODING>::to_raw (const vector<float>& samp
 
 template<int BIT_DEPTH, RawFormat::Endian ENDIAN, RawFormat::Encoding ENCODING>
 void
-RawConverterImpl<BIT_DEPTH, ENDIAN, ENCODING>::from_raw (const vector<unsigned char>& input_bytes, vector<float>& samples)
+RawConverterImpl<BIT_DEPTH, ENDIAN, ENCODING>::from_raw (const unsigned char *input_bytes, float *samples, size_t n_samples)
 {
-  const unsigned char *ptr = input_bytes.data();
+  const unsigned char *ptr = input_bytes;
   constexpr int sample_width = BIT_DEPTH / 8;
   constexpr auto eshift = make_endian_shift<BIT_DEPTH, ENDIAN>();
   constexpr unsigned char sign_flip = ENCODING == RawFormat::SIGNED ? 0x00 : 0x80;
@@ -177,11 +177,10 @@ RawConverterImpl<BIT_DEPTH, ENDIAN, ENCODING>::from_raw (const vector<unsigned c
 #else
   constexpr bool native_endian = ENDIAN == RawFormat::LITTLE;
 #endif
-  assert ((uintptr_t (input_bytes.data()) & 3) == 0); // ensure alignment for optimized 32 bit native endian version
+  assert ((uintptr_t (input_bytes) & 3) == 0); // ensure alignment for optimized 32 bit native endian version
 
-  samples.resize (input_bytes.size() / sample_width);
   const float norm = 1.0 / 0x80000000LL;
-  for (size_t i = 0; i < samples.size(); i++)
+  for (size_t i = 0; i < n_samples; i++)
     {
       if (native_endian && ENCODING == RawFormat::SIGNED && BIT_DEPTH == 32)
         samples[i] = ((int32_t *)ptr)[i] * norm;

src/rawconverter.hh

@@ -28,7 +28,7 @@ public:
   virtual ~RawConverter() = 0;
 
   virtual void to_raw   (const std::vector<float>& samples, std::vector<unsigned char>& bytes) = 0;
-  virtual void from_raw (const std::vector<unsigned char>& bytes, std::vector<float>& samples) = 0;
+  virtual void from_raw (const unsigned char *bytes, float *samples, size_t n_samples) = 0;
 };
 
 #endif /* AUDIOWMARK_RAW_CONVERTER_HH */

src/rawinputstream.cc

@@ -146,7 +146,7 @@ RawInputStream::read_frames (vector<float>& samples, size_t count)
 
   input_bytes.resize (r_count * n_channels * sample_width);
 
-  m_raw_converter->from_raw (input_bytes, samples);
+  m_raw_converter->from_raw (input_bytes.data(), samples.data(), r_count * n_channels);
 
   return Error::Code::NONE;
 }

src/wavpipeinputstream.cc

@@ -25,6 +25,7 @@
 using std::string;
 using std::vector;
 using std::min;
+using std::max;
 
 WavPipeInputStream::~WavPipeInputStream()
 {
@@ -153,18 +154,34 @@ WavPipeInputStream::read_frames (vector<float>& samples, size_t count)
 {
   assert (m_state == State::OPEN);
 
+  const size_t block_size = 1024;
   const int n_channels   = m_format.n_channels();
   const int sample_width = m_format.bit_depth() / 8;
 
-  vector<unsigned char> input_bytes (count * n_channels * sample_width);
-  size_t r_count = fread (input_bytes.data(), n_channels * sample_width, count, m_input_file);
-  if (ferror (m_input_file))
-    return Error ("error reading sample data");
+  m_input_bytes.resize (block_size * n_channels * sample_width);
+  size_t pos = 0;
 
-  input_bytes.resize (r_count * n_channels * sample_width);
+  for (;;)
+    {
+      size_t todo = min (count, block_size);
+      if (!todo)
+        break;
+
+      size_t r_count = fread (m_input_bytes.data(), n_channels * sample_width, todo, m_input_file);
+      if (ferror (m_input_file))
+        return Error ("error reading sample data");
+
+      if (!r_count)
+        break;
 
-  m_raw_converter->from_raw (input_bytes, samples);
+      samples.resize (max (samples.size(), (pos + r_count) * n_channels));
 
+      m_raw_converter->from_raw (m_input_bytes.data(), samples.data() + pos * n_channels, r_count * n_channels);
+
+      pos += r_count;
+      count -= r_count;
+    }
+  samples.resize (pos * n_channels);
   return Error::Code::NONE;
 }
 

src/wavpipeinputstream.hh

@@ -38,6 +38,7 @@ class WavPipeInputStream : public AudioInputStream
   FILE       *m_input_file = nullptr;
   bool        m_close_file = false;
 
+  std::vector<unsigned char>    m_input_bytes;
   std::unique_ptr<RawConverter> m_raw_converter;
 
 public: