Feature: add pcm processor

app/CMakeLists.txt

@@ -45,6 +45,7 @@ add_library( # Sets the name of the library.
             src/main/cpp/yuv/yuv_converter.cpp
             src/main/cpp/media_transcode.cpp
             src/main/cpp/audio_resample.cpp
+            src/main/cpp/pcm/pcm_process.cpp
         )
 
 add_library( ffmpeg

app/src/main/cpp/pcm/pcm_process.cpp

@@ -0,0 +1,93 @@
+//
+// Created by xu fulong on 2022/8/5.
+//
+
+#include <cstdio>
+#include <cerrno>
+#include <cstdlib>
+#include <cstring>
+
+void pcm_raise_speed(char *input_path, char *output_path)
+{
+    FILE *input = fopen(input_path, "rb+");
+    FILE *output = fopen(output_path, "wb+");
+    if (!input && !output) {
+        printf("open file fail, msg=%s\n", strerror(errno));
+        return;
+    }
+
+    int count = 0;
+    char *buf = (char*) malloc(sizeof(char) * 4);
+    while(!feof(input)) {
+        fread(buf, sizeof(char), 4, input);
+        if (count % 2 == 0) {
+            // L
+            fwrite(buf, sizeof(char), 2, output);
+            // R
+            fwrite(buf + 2, sizeof(char), 2, output);
+        }
+        count++;
+    }
+
+    free(buf);
+    fclose(output);
+    fclose(input);
+}
+
+void pcm_change_volume(char *input_path, char *output_path)
+{
+    FILE *input = fopen(input_path, "rb+");
+    FILE *output = fopen(output_path, "wb+");
+    if (!input && !output) {
+        printf("open file fail, msg=%s\n", strerror(errno));
+        return;
+    }
+
+    int count = 0;
+    char *buf = (char*) malloc(sizeof(char) * 4);
+    while(!feof(input)) {
+        fread(buf, sizeof(char), 4, input);
+        short *left = (short*) buf;
+        *left /= 2;
+        short *right = (short*) (buf + 2);
+        *right /= 2;
+        // L
+        fwrite(left, sizeof(short), 1, output);
+        // R
+        fwrite(right, sizeof(short), 1, output);
+        count++;
+    }
+    printf("resample count=%d\n", count);
+
+    free(buf);
+    fclose(output);
+    fclose(input);
+}
+
+void pcm_split_channel(char *input_path, char *left_path, char *right_path)
+{
+    FILE *input = fopen(input_path, "rb+");
+    FILE *left = fopen(left_path, "wb+");
+    FILE *right = fopen(right_path, "wb+");
+    if (!input && !left && !right) {
+        printf("open file fail, msg=%s\n", strerror(errno));
+        return;
+    }
+
+    int count = 0;
+    char *buf = (char*) malloc(sizeof(char) * 4);
+    while(!feof(input)) {
+        fread(buf, sizeof(char), 4, input);
+        // L
+        fwrite(buf, sizeof(char), 2, left);
+        // R
+        fwrite(buf+2, sizeof(char), 2, right);
+        count++;
+    }
+    printf("resample count=%d\n", count);
+
+    free(buf);
+    fclose(left);
+    fclose(right);
+    fclose(input);
+}