Implement skip() function for Limiter.

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

src/limiter.cc

@@ -66,6 +66,28 @@ Limiter::process (const vector<float>& samples)
   return out;
 }
 
+size_t
+Limiter::skip (size_t zeros)
+{
+  vector<float> samples (zeros * n_channels);
+
+  assert (block_size >= 1);
+  assert (samples.size() % n_channels == 0);    // process should be called with whole frames
+
+  buffer.insert (buffer.end(), samples.begin(), samples.end());
+
+  /* need at least two complete blocks in buffer to produce output */
+  const uint buffered_blocks = buffer.size() / n_channels / block_size;
+  if (buffered_blocks < 2)
+    return 0;
+
+  const uint blocks_todo = buffered_blocks - 1;
+
+  buffer.erase (buffer.begin(), buffer.begin() + blocks_todo * block_size * n_channels);
+
+  return blocks_todo * block_size;
+}
+
 float
 Limiter::block_max (const float *in)
 {

src/limiter.hh

@@ -42,6 +42,7 @@ public:
   void set_ceiling (float ceiling);
 
   std::vector<float> process (const std::vector<float>& samples);
+  size_t             skip (size_t zeros);
   std::vector<float> flush();
 };
 

src/wmadd.cc

@@ -670,13 +670,12 @@ add_stream_watermark (AudioInputStream *in_stream, AudioOutputStream *out_stream
     {
       total_input_frames += Params::frame_size;
       audio_buffer_frames += Params::frame_size;
-      samples.assign (wm_resampler.skip (Params::frame_size) * n_channels, 0);
-      size_t to_read = samples.size() / n_channels;
-      audio_buffer_frames -= to_read;
+      size_t frames = wm_resampler.skip (Params::frame_size);
+      audio_buffer_frames -= frames;
 
-      samples = limiter.process (samples);
+      frames = limiter.skip (frames);
 
-      err = out_stream->write_frames (samples);
+      err = out_stream->write_frames (vector<float> (frames * n_channels));
       total_output_frames += samples.size() / n_channels;
 
       zero_frames -= Params::frame_size;