4 files changed, 180 insertions, 25 deletions
diff --git a/src/audio/include/fir.h b/src/audio/include/fir.h
new file mode 100644
index 00000000..e50c3eff
--- /dev/null
+++ b/src/audio/include/fir.h
@@ -0,0 +1,131 @@
+/*
+ * FIR filter coefficients from resample-1.x smallfilter.h 
+ * see Digital Audio Resampling Home Page located at
+ * http://ccrma.stanford.edu/~jos/resample/
+ */
+32767, 32766, 32764, 32760, 32755, 32749, 32741, 32731, 32721, 32708,
+32695, 32679, 32663, 32645, 32625, 32604, 32582, 32558, 32533, 32506,
+32478, 32448, 32417, 32385, 32351, 32316, 32279, 32241, 32202, 32161,
+32119, 32075, 32030, 31984, 31936, 31887, 31836, 31784, 31731, 31676,
+31620, 31563, 31504, 31444, 31383, 31320, 31256, 31191, 31124, 31056,
+30987, 30916, 30845, 30771, 30697, 30621, 30544, 30466, 30387, 30306,
+30224, 30141, 30057, 29971, 29884, 29796, 29707, 29617, 29525, 29433,
+29339, 29244, 29148, 29050, 28952, 28852, 28752, 28650, 28547, 28443,
+28338, 28232, 28125, 28017, 27908, 27797, 27686, 27574, 27461, 27346,
+27231, 27115, 26998, 26879, 26760, 26640, 26519, 26398, 26275, 26151,
+26027, 25901, 25775, 25648, 25520, 25391, 25262, 25131, 25000, 24868,
+24735, 24602, 24467, 24332, 24197, 24060, 23923, 23785, 23647, 23507,
+23368, 23227, 23086, 22944, 22802, 22659, 22515, 22371, 22226, 22081,
+21935, 21789, 21642, 21494, 21346, 21198, 21049, 20900, 20750, 20600,
+20449, 20298, 20146, 19995, 19842, 19690, 19537, 19383, 19230, 19076,
+18922, 18767, 18612, 18457, 18302, 18146, 17990, 17834, 17678, 17521,
+17365, 17208, 17051, 16894, 16737, 16579, 16422, 16264, 16106, 15949,
+15791, 15633, 15475, 15317, 15159, 15001, 14843, 14685, 14527, 14369,
+14212, 14054, 13896, 13739, 13581, 13424, 13266, 13109, 12952, 12795,
+12639, 12482, 12326, 12170, 12014, 11858, 11703, 11548, 11393, 11238,
+11084, 10929, 10776, 10622, 10469, 10316, 10164, 10011, 9860, 9708,
+9557, 9407, 9256, 9106, 8957, 8808, 8659, 8511, 8364, 8216, 8070,
+7924, 7778, 7633, 7488, 7344, 7200, 7057, 6914, 6773, 6631, 6490,
+6350, 6210, 6071, 5933, 5795, 5658, 5521, 5385, 5250, 5115, 4981,
+4848, 4716, 4584, 4452, 4322, 4192, 4063, 3935, 3807, 3680, 3554,
+3429, 3304, 3180, 3057, 2935, 2813, 2692, 2572, 2453, 2335, 2217,
+2101, 1985, 1870, 1755, 1642, 1529, 1418, 1307, 1197, 1088, 979, 872,
+765, 660, 555, 451, 348, 246, 145, 44, -54, -153, -250, -347, -443,
+-537, -631, -724, -816, -908, -998, -1087, -1175, -1263, -1349, -1435,
+-1519, -1603, -1685, -1767, -1848, -1928, -2006, -2084, -2161, -2237,
+-2312, -2386, -2459, -2531, -2603, -2673, -2742, -2810, -2878, -2944,
+-3009, -3074, -3137, -3200, -3261, -3322, -3381, -3440, -3498, -3554,
+-3610, -3665, -3719, -3772, -3824, -3875, -3925, -3974, -4022, -4069,
+-4116, -4161, -4205, -4249, -4291, -4333, -4374, -4413, -4452, -4490,
+-4527, -4563, -4599, -4633, -4666, -4699, -4730, -4761, -4791, -4820,
+-4848, -4875, -4901, -4926, -4951, -4974, -4997, -5019, -5040, -5060,
+-5080, -5098, -5116, -5133, -5149, -5164, -5178, -5192, -5205, -5217,
+-5228, -5238, -5248, -5257, -5265, -5272, -5278, -5284, -5289, -5293,
+-5297, -5299, -5301, -5303, -5303, -5303, -5302, -5300, -5298, -5295,
+-5291, -5287, -5282, -5276, -5270, -5263, -5255, -5246, -5237, -5228,
+-5217, -5206, -5195, -5183, -5170, -5157, -5143, -5128, -5113, -5097,
+-5081, -5064, -5047, -5029, -5010, -4991, -4972, -4952, -4931, -4910,
+-4889, -4867, -4844, -4821, -4797, -4774, -4749, -4724, -4699, -4673,
+-4647, -4620, -4593, -4566, -4538, -4510, -4481, -4452, -4422, -4393,
+-4363, -4332, -4301, -4270, -4238, -4206, -4174, -4142, -4109, -4076,
+-4042, -4009, -3975, -3940, -3906, -3871, -3836, -3801, -3765, -3729,
+-3693, -3657, -3620, -3584, -3547, -3510, -3472, -3435, -3397, -3360,
+-3322, -3283, -3245, -3207, -3168, -3129, -3091, -3052, -3013, -2973,
+-2934, -2895, -2855, -2816, -2776, -2736, -2697, -2657, -2617, -2577,
+-2537, -2497, -2457, -2417, -2377, -2337, -2297, -2256, -2216, -2176,
+-2136, -2096, -2056, -2016, -1976, -1936, -1896, -1856, -1817, -1777,
+-1737, -1698, -1658, -1619, -1579, -1540, -1501, -1462, -1423, -1384,
+-1345, -1306, -1268, -1230, -1191, -1153, -1115, -1077, -1040, -1002,
+-965, -927, -890, -854, -817, -780, -744, -708, -672, -636, -600,
+-565, -530, -494, -460, -425, -391, -356, -322, -289, -255, -222,
+-189, -156, -123, -91, -59, -27, 4, 35, 66, 97, 127, 158, 188, 218,
+247, 277, 306, 334, 363, 391, 419, 447, 474, 501, 528, 554, 581, 606,
+632, 657, 683, 707, 732, 756, 780, 803, 827, 850, 872, 895, 917, 939,
+960, 981, 1002, 1023, 1043, 1063, 1082, 1102, 1121, 1139, 1158, 1176,
+1194, 1211, 1228, 1245, 1262, 1278, 1294, 1309, 1325, 1340, 1354,
+1369, 1383, 1397, 1410, 1423, 1436, 1448, 1461, 1473, 1484, 1496,
+1507, 1517, 1528, 1538, 1548, 1557, 1566, 1575, 1584, 1592, 1600,
+1608, 1616, 1623, 1630, 1636, 1643, 1649, 1654, 1660, 1665, 1670,
+1675, 1679, 1683, 1687, 1690, 1694, 1697, 1700, 1702, 1704, 1706,
+1708, 1709, 1711, 1712, 1712, 1713, 1713, 1713, 1713, 1712, 1711,
+1710, 1709, 1708, 1706, 1704, 1702, 1700, 1697, 1694, 1691, 1688,
+1685, 1681, 1677, 1673, 1669, 1664, 1660, 1655, 1650, 1644, 1639,
+1633, 1627, 1621, 1615, 1609, 1602, 1596, 1589, 1582, 1575, 1567,
+1560, 1552, 1544, 1536, 1528, 1520, 1511, 1503, 1494, 1485, 1476,
+1467, 1458, 1448, 1439, 1429, 1419, 1409, 1399, 1389, 1379, 1368,
+1358, 1347, 1337, 1326, 1315, 1304, 1293, 1282, 1271, 1260, 1248,
+1237, 1225, 1213, 1202, 1190, 1178, 1166, 1154, 1142, 1130, 1118,
+1106, 1094, 1081, 1069, 1057, 1044, 1032, 1019, 1007, 994, 981, 969,
+956, 943, 931, 918, 905, 892, 879, 867, 854, 841, 828, 815, 802, 790,
+777, 764, 751, 738, 725, 713, 700, 687, 674, 662, 649, 636, 623, 611,
+598, 585, 573, 560, 548, 535, 523, 510, 498, 486, 473, 461, 449, 437,
+425, 413, 401, 389, 377, 365, 353, 341, 330, 318, 307, 295, 284, 272,
+261, 250, 239, 228, 217, 206, 195, 184, 173, 163, 152, 141, 131, 121,
+110, 100, 90, 80, 70, 60, 51, 41, 31, 22, 12, 3, -5, -14, -23, -32,
+-41, -50, -59, -67, -76, -84, -93, -101, -109, -117, -125, -133, -140,
+-148, -156, -163, -170, -178, -185, -192, -199, -206, -212, -219,
+-226, -232, -239, -245, -251, -257, -263, -269, -275, -280, -286,
+-291, -297, -302, -307, -312, -317, -322, -327, -332, -336, -341,
+-345, -349, -354, -358, -362, -366, -369, -373, -377, -380, -384,
+-387, -390, -394, -397, -400, -402, -405, -408, -411, -413, -416,
+-418, -420, -422, -424, -426, -428, -430, -432, -433, -435, -436,
+-438, -439, -440, -442, -443, -444, -445, -445, -446, -447, -447,
+-448, -448, -449, -449, -449, -449, -449, -449, -449, -449, -449,
+-449, -449, -448, -448, -447, -447, -446, -445, -444, -443, -443,
+-442, -441, -440, -438, -437, -436, -435, -433, -432, -430, -429,
+-427, -426, -424, -422, -420, -419, -417, -415, -413, -411, -409,
+-407, -405, -403, -400, -398, -396, -393, -391, -389, -386, -384,
+-381, -379, -376, -374, -371, -368, -366, -363, -360, -357, -355,
+-352, -349, -346, -343, -340, -337, -334, -331, -328, -325, -322,
+-319, -316, -313, -310, -307, -304, -301, -298, -294, -291, -288,
+-285, -282, -278, -275, -272, -269, -265, -262, -259, -256, -252,
+-249, -246, -243, -239, -236, -233, -230, -226, -223, -220, -217,
+-213, -210, -207, -204, -200, -197, -194, -191, -187, -184, -181,
+-178, -175, -172, -168, -165, -162, -159, -156, -153, -150, -147,
+-143, -140, -137, -134, -131, -128, -125, -122, -120, -117, -114,
+-111, -108, -105, -102, -99, -97, -94, -91, -88, -86, -83, -80, -78,
+-75, -72, -70, -67, -65, -62, -59, -57, -55, -52, -50, -47, -45, -43,
+-40, -38, -36, -33, -31, -29, -27, -25, -22, -20, -18, -16, -14, -12,
+-10, -8, -6, -4, -2, 0, 0, 2, 4, 6, 8, 9, 11, 13, 14, 16, 17, 19, 21,
+22, 24, 25, 27, 28, 29, 31, 32, 33, 35, 36, 37, 38, 40, 41, 42, 43,
+44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59,
+59, 60, 61, 62, 62, 63, 63, 64, 64, 65, 66, 66, 66, 67, 67, 68, 68,
+69, 69, 69, 70, 70, 70, 70, 71, 71, 71, 71, 71, 72, 72, 72, 72, 72,
+72, 72, 72, 72, 72, 72, 72, 72, 72, 72, 72, 72, 72, 72, 72, 72, 72,
+72, 71, 71, 71, 71, 71, 70, 70, 70, 70, 69, 69, 69, 69, 68, 68, 68,
+67, 67, 67, 66, 66, 66, 65, 65, 64, 64, 64, 63, 63, 62, 62, 62, 61,
+61, 60, 60, 59, 59, 58, 58, 58, 57, 57, 56, 56, 55, 55, 54, 54, 53,
+53, 52, 52, 51, 51, 50, 50, 49, 48, 48, 47, 47, 46, 46, 45, 45, 44,
+44, 43, 43, 42, 42, 41, 41, 40, 39, 39, 38, 38, 37, 37, 36, 36, 35,
+35, 34, 34, 33, 33, 32, 32, 31, 31, 30, 30, 29, 29, 28, 28, 27, 27,
+26, 26, 25, 25, 24, 24, 23, 23, 23, 22, 22, 21, 21, 20, 20, 20, 19,
+19, 18, 18, 17, 17, 17, 16, 16, 15, 15, 15, 14, 14, 14, 13, 13, 12,
+12, 12, 11, 11, 11, 10, 10, 10, 9, 9, 9, 9, 8, 8, 8, 7, 7, 7, 7, 6, 6,
+6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 1, 1, 1,
+1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1,
+-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -2, -2, -2, -2, -2,
+-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
+-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
+-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
+-2, -2, -2, -2, -2, -2, -2, -2, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
diff --git a/src/audio/include/resample.hpp b/src/audio/include/resample.hpp
new file mode 100644
index 00000000..d7933470
--- /dev/null
+++ b/src/audio/include/resample.hpp
@@ -0,0 +1,41 @@
+#pragma once
+
+#include <sys/_stdint.h>
+#include <vector>
+
+#include "span.hpp"
+
+#include "sample.hpp"
+
+namespace audio {
+
+class Channel;
+
+class Resampler {
+ public:
+  Resampler(uint32_t source_sample_rate,
+            uint32_t target_sample_rate,
+            uint8_t num_channels);
+
+  ~Resampler();
+
+  auto source_sample_rate() -> uint32_t { return source_sample_rate_; }
+  auto target_sample_rate() -> uint32_t { return target_sample_rate_; }
+  auto channels() -> uint_fast8_t { return num_channels_; }
+
+  auto Process(cpp::span<const sample::Sample> input,
+               cpp::span<sample::Sample> output,
+               bool end_of_data) -> std::pair<size_t,size_t>;
+
+ private:
+  auto ApplyDither(cpp::span<sample::Sample>) -> void;
+
+  uint32_t source_sample_rate_;
+  uint32_t target_sample_rate_;
+  uint32_t factor_;
+
+  uint8_t num_channels_;
+  std::vector<Channel> channels_;
+};
+
+}  // namespace audio
+\ No newline at end of file
diff --git a/src/audio/include/sink_mixer.hpp b/src/audio/include/sink_mixer.hpp
index 632ffa2e..1bf12016 100644
--- a/src/audio/include/sink_mixer.hpp
+++ b/src/audio/include/sink_mixer.hpp
@@ -10,6 +10,8 @@
 #include <cstdint>
 #include <memory>
 
+#include "resample.hpp"
+#include "sample.hpp"
 #include "samplerate.h"
 
 #include "audio_decoder.hpp"
@@ -38,12 +40,10 @@ class SinkMixer {
   auto SetTargetFormat(const StreamInfo::Pcm& format) -> void;
   auto HandleBytes() -> void;
 
-  template <typename T>
-  auto ConvertFixedToFloating(InputStream&, OutputStream&) -> void;
-  auto Resample(float, int, InputStream&, OutputStream&) -> void;
-  template <typename T>
-  auto Quantise(InputStream&) -> std::size_t;
-
+  auto Resample(InputStream&, OutputStream&) -> bool;
+  auto ApplyDither(cpp::span<sample::Sample> samples, uint_fast8_t bits) -> void;
+  auto Downscale(cpp::span<sample::Sample>, cpp::span<int16_t>) -> void;
+ 
   enum class Command {
     kReadBytes,
     kSetSourceFormat,
@@ -58,31 +58,14 @@ class SinkMixer {
   QueueHandle_t commands_;
   SemaphoreHandle_t is_idle_;
 
-  SRC_STATE* resampler_;
+  std::unique_ptr<Resampler> resampler_;
 
   std::unique_ptr<RawStream> input_stream_;
-  std::unique_ptr<RawStream> floating_point_stream_;
   std::unique_ptr<RawStream> resampled_stream_;
 
-  cpp::span<std::byte> quantisation_buffer_;
-  cpp::span<short> quantisation_buffer_as_shorts_;
-  cpp::span<int> quantisation_buffer_as_ints_;
-
   StreamInfo::Pcm target_format_;
   StreamBufferHandle_t source_;
   StreamBufferHandle_t sink_;
 };
 
-template <>
-auto SinkMixer::ConvertFixedToFloating<short>(InputStream&, OutputStream&)
-    -> void;
-template <>
-auto SinkMixer::ConvertFixedToFloating<int>(InputStream&, OutputStream&)
-    -> void;
-
-template <>
-auto SinkMixer::Quantise<short>(InputStream&) -> std::size_t;
-template <>
-auto SinkMixer::Quantise<int>(InputStream&) -> std::size_t;
-
 }  // namespace audio
diff --git a/src/audio/include/stream_info.hpp b/src/audio/include/stream_info.hpp
index 7cf9e847..01dd282a 100644
--- a/src/audio/include/stream_info.hpp
+++ b/src/audio/include/stream_info.hpp
@@ -77,7 +77,7 @@ class StreamInfo {
     // The sample rate.
     uint32_t sample_rate;
 
-    auto real_bytes_per_sample() const -> uint8_t {
+    auto bytes_per_sample() const -> uint8_t {
       return bits_per_sample == 16 ? 2 : 4;
     }