r1

Makefile

@@ -0,0 +1,8 @@
+default: aac_split.exe
+
+aac_split.exe: aac_split.o
+	g++ -static -static-libgcc -static-libstdc++ -o $@ $<
+	strip $@
+
+aac_split.o: aac_split.cpp
+	g++ -O2 --std=c++11 -c aac_split.cpp

aac_split.cpp

@@ -0,0 +1,95 @@
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <iostream>
+#include <fstream>
+
+using namespace std;
+
+#define ADTS_channel(header) (((header[2] & 0x1) << 2) | ((header[3] & 0xC0) >> 6))
+#define ADTS_length(header) (((header[3] & 0x3) << 11) | (header[4] << 3) | ((header[5] & 0xE0) >> 5))
+
+char* name_prefix;
+char out_filename[10240] = {0};
+
+size_t total = 0;
+
+void show_progress(size_t progress) {
+    printf("%7d/%d MB %.2lf%%     \r", progress >> 20, total >> 20, progress * 100.0 / total);
+}
+
+void split_aac(const char * aac_filename) {
+    unsigned int file_index = 0;
+    unsigned int block_index = 0;
+    int last_channel = -1;
+    int len = strlen(aac_filename) - 3;
+    name_prefix = new char[len];
+    strncpy(name_prefix, aac_filename, len - 1);
+    name_prefix[len - 1] = 0;
+    printf("Opening %s\n", aac_filename);
+    ifstream input(aac_filename, ios::in | ios::binary);
+    ofstream output;
+    unsigned char header[7];
+    char buffer[1<<13];
+    int i = 0;
+    // Get total
+    auto beginning = input.tellg();
+    input.seekg(0, ios::end);
+    total = input.tellg() - beginning;
+    input.seekg(0, ios::beg);
+    while(!input.eof()) {
+        input.read((char*) header, 7);
+        if(header[0] != 0xFF || header[1] & 0xF0 != 0xF0) {
+            printf("%d %d --\n", header[0], header[1]);
+            printf("Data is corrupted at %ld\n", input.tellg() - beginning);
+            return;
+        }
+        input.read(buffer, ADTS_length(header) - 7);
+        if(ADTS_channel(header) != last_channel) {
+            // Channel configuration has changed, writing to new destination
+            if(output.is_open())
+                output.close();
+            last_channel = ADTS_channel(header);
+            sprintf(out_filename, "%s_%d_%dch.aac", name_prefix, ++file_index, ADTS_channel(header));
+            printf("Saving to %s ...                    \n", out_filename);
+            output.open(out_filename, ios::out | ios::binary | ios::trunc);
+        }
+        output.write((char*) header, 7);
+        output.write(buffer, ADTS_length(header) - 7);
+        if((block_index & 0x1FFF) == 0)
+            show_progress(input.tellg() - beginning);
+        block_index++;
+    }
+    show_progress(total);
+    if(output.is_open())
+        output.close();
+}
+
+void help(const char * argv[]) {
+    printf("%s <file.aac> ...\n", argv[0]);
+    puts("");
+    puts("Split AAC with multiple channel configurations into segments.");
+    puts("");
+    puts("CAUTION! 'file_X_Ych.aac' will be overwritten without confirmation!");
+    puts("");
+}
+
+int main(int argc, const char * argv[]) {
+    if (argc < 2) {
+        help(argv);
+        return -1;
+    }
+
+    for (int i = 1; i < argc; i++) {
+        const char* aac_filename = argv[i];
+        const char* extension = aac_filename + strlen(aac_filename) - 4;
+        if (strcmp(extension, ".aac") != 0) {
+            printf("Only .aac file is accepted, %s given.\n", aac_filename);
+            return -2;
+        }
+
+        split_aac(aac_filename);
+    }
+
+    return 0;
+}