c-api add wave write to buffer. (#1962)

Co-authored-by: jian.chen03 <jian.chen03@transwarp.io>

@@ -136,3 +136,6 @@ kokoro-multi-lang-v1_0
 sherpa-onnx-fire-red-asr-large-zh_en-2025-02-16
 cmake-build-debug
 README-DEV.txt
+
+##clion
+.idea
\ No newline at end of file

@@ -1337,6 +1337,16 @@ int32_t SherpaOnnxWriteWave(const float *samples, int32_t n,
   return sherpa_onnx::WriteWave(filename, sample_rate, samples, n);
 }
 
+int64_t SherpaOnnxWaveFileSize(int32_t n_samples) {
+  return sherpa_onnx::WaveFileSize(n_samples);
+}
+
+SHERPA_ONNX_API void SherpaOnnxWriteWaveToBuffer(const float *samples,
+                                                 int32_t n, int32_t sample_rate,
+                                                 char *buffer) {
+  sherpa_onnx::WriteWave(buffer, sample_rate, samples, n);
+}
+
 const SherpaOnnxWave *SherpaOnnxReadWave(const char *filename) {
   int32_t sample_rate = -1;
   bool is_ok = false;

@@ -1049,6 +1049,18 @@ SHERPA_ONNX_API int32_t SherpaOnnxWriteWave(const float *samples, int32_t n,
                                             int32_t sample_rate,
                                             const char *filename);
 
+// the amount of bytes needed to store a wave file which contains a
+// single channel and has 16-bit samples.
+SHERPA_ONNX_API int64_t SherpaOnnxWaveFileSize(int32_t n_samples);
+
+// Similar to SherpaOnnxWriteWave , it writes wave to allocated  buffer;
+//
+// in some case (http tts api return wave binary file, server do not need to
+// write wave to fs)
+SHERPA_ONNX_API void SherpaOnnxWriteWaveToBuffer(const float *samples,
+                                                 int32_t n, int32_t sample_rate,
+                                                 char *buffer);
+
 SHERPA_ONNX_API typedef struct SherpaOnnxWave {
   // samples normalized to the range [-1, 1]
   const float *samples;

@@ -4,6 +4,7 @@
 
 #include "sherpa-onnx/csrc/wave-writer.h"
 
+#include <cstring>
 #include <fstream>
 #include <string>
 #include <vector>
@@ -35,8 +36,12 @@ struct WaveHeader {
 
 }  // namespace
 
-bool WriteWave(const std::string &filename, int32_t sampling_rate,
-               const float *samples, int32_t n) {
+int64_t WaveFileSize(int32_t n_samples) {
+  return sizeof(WaveHeader) + n_samples * sizeof(int16_t);
+}
+
+void WriteWave(char *buffer, int32_t sampling_rate, const float *samples,
+               int32_t n) {
   WaveHeader header{};
   header.chunk_id = 0x46464952;      // FFIR
   header.format = 0x45564157;        // EVAW
@@ -61,21 +66,26 @@ bool WriteWave(const std::string &filename, int32_t sampling_rate,
     samples_int16[i] = samples[i] * 32676;
   }
 
+  memcpy(buffer, &header, sizeof(WaveHeader));
+  memcpy(buffer + sizeof(WaveHeader), samples_int16.data(),
+         n * sizeof(int16_t));
+}
+
+bool WriteWave(const std::string &filename, int32_t sampling_rate,
+               const float *samples, int32_t n) {
+  std::string buffer;
+  buffer.resize(WaveFileSize(n));
+  WriteWave(buffer.data(), sampling_rate, samples, n);
   std::ofstream os(filename, std::ios::binary);
   if (!os) {
     SHERPA_ONNX_LOGE("Failed to create %s", filename.c_str());
     return false;
   }
-
-  os.write(reinterpret_cast<const char *>(&header), sizeof(header));
-  os.write(reinterpret_cast<const char *>(samples_int16.data()),
-           samples_int16.size() * sizeof(int16_t));
-
+  os << buffer;
   if (!os) {
     SHERPA_ONNX_LOGE("Write %s failed", filename.c_str());
     return false;
   }
-
   return true;
 }
 

@@ -22,6 +22,11 @@ namespace sherpa_onnx {
 bool WriteWave(const std::string &filename, int32_t sampling_rate,
                const float *samples, int32_t n);
 
+void WriteWave(char *buffer, int32_t sampling_rate, const float *samples,
+               int32_t n);
+
+int64_t WaveFileSize(int32_t n_samples);
+
 }  // namespace sherpa_onnx
 
 #endif  // SHERPA_ONNX_CSRC_WAVE_WRITER_H_