Allow reading and writting 24bits files

audionamix · Oct 31, 2017 · 321595a · 321595a
1 parent 1603954
commit 321595a
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Showing 2 changed files with 58 additions and 0 deletions.
diff --git a/src/wave/file.cc b/src/wave/file.cc
@@ -7,6 +7,8 @@
 
 #include "wave/headers.h"
 
+#define INT24_MAX 8388607
+
 namespace wave {
 
 namespace internal {
@@ -216,6 +218,19 @@ Error File::Read(uint64_t frame_number, void (*decrypt)(char*, size_t),
       decrypt(reinterpret_cast<char*>(&value), sizeof(value) / sizeof(char));
       (*output)[sample_idx] =
           static_cast<float>(value) / std::numeric_limits<int16_t>::max();
+    } else if (impl_->header.fmt.bits_per_sample == 24) {
+      // 24bits int doesn't exist in c++. We create a 3 * 8bits struct to simulate
+      unsigned char value[3];
+      impl_->istream.read(reinterpret_cast<char*>(&value), sizeof(value));
+      decrypt(reinterpret_cast<char*>(&value), sizeof(value) / sizeof(char));
+      int integer_value;
+      // check if value is negative
+      if ( value[2] & 0x80 ) {
+        integer_value = (0xff << 24) | (value[2] << 16) | (value[1] << 8) | (value[0] << 0);
+      } else {
+        integer_value = (value[2] << 16) | (value[1] << 8) | (value[0] << 0);
+      }
+      (*output)[sample_idx] = static_cast<float>(integer_value) / INT24_MAX;
     } else if (impl_->header.fmt.bits_per_sample == 32) {
       // 32bits
       int32_t value;
@@ -257,6 +272,16 @@ Error File::Write(const std::vector<float>& data,
           static_cast<int16_t>(sample * std::numeric_limits<int16_t>::max());
       encrypt(reinterpret_cast<char*>(&value), sizeof(value) / sizeof(char));
       impl_->ostream.write(reinterpret_cast<char*>(&value), sizeof(value));
+    } else if (bits_per_sample == 24) {
+      // 24bits int doesn't exist in c++. We create a 3 * 8bits struct to simulate
+      int v = sample * INT24_MAX;
+      int8_t value[3];
+      value[0] = reinterpret_cast<char*>(&v)[0];
+      value[1] = reinterpret_cast<char*>(&v)[1];
+      value[2] = reinterpret_cast<char*>(&v)[2];
+
+      encrypt(reinterpret_cast<char*>(&value), sizeof(value) / sizeof(char));
+      impl_->ostream.write(reinterpret_cast<char*>(&value), sizeof(value));
     } else if (bits_per_sample == 32) {
       // 32bits
       int32_t value =

diff --git a/src/wave/file_test.cc b/src/wave/file_test.cc
@@ -135,6 +135,39 @@ TEST(Wave, ChunkWrite) {
   ASSERT_EQ(content, re_read_content);
 }
 
+TEST(Wave, Write24bits) {
+  using namespace wave;
+
+  // tested above
+  File read_file;
+  read_file.Open(gResourcePath + "/Untitled3.wav", OpenMode::kIn);
+  std::vector<float> content;
+  read_file.Read(&content);
+
+  {
+    File write_file;
+    write_file.Open(gResourcePath + "/output.wav", OpenMode::kOut);
+    write_file.set_sample_rate(read_file.sample_rate());
+    write_file.set_bits_per_sample(24);
+    write_file.set_channel_number(read_file.channel_number());
+    write_file.Write(content);
+  }
+
+  // re read
+  File re_read_file;
+  re_read_file.Open(gResourcePath + "/output.wav", OpenMode::kIn);
+  std::vector<float> re_read_content;
+  re_read_file.Read(&re_read_content);
+
+  ASSERT_EQ(read_file.channel_number(), re_read_file.channel_number());
+  ASSERT_EQ(read_file.sample_rate(), re_read_file.sample_rate());
+  ASSERT_EQ(read_file.channel_number(), re_read_file.channel_number());
+  ASSERT_EQ(re_read_file.bits_per_sample(), 24);
+  for (int i = 0; i < read_file.frame_number(); i++) {
+    ASSERT_LT(fabs(content[i] - re_read_content[i]), pow(10, -6));
+  }
+}
+
 #if __cplusplus > 199711L
 TEST(Wave, ReadModern) {
   using namespace wave;