h264起始碼
h264文件的NALU的起始碼可以是0x00 0x00 0x01或者0x00 0x00 0x00 0x01
代碼實現
以下通過代碼功能可以格式化h264文件爲任意一種起始碼類型。
int h264_format_start_code(const char *dst, const char *src, int type /* 0 for 001, 1 for 0001 */)
dst：輸出格式化後的h264文件
src：輸入原始的h264文件
type：0 格式化爲0x00 0x00 0x01，1 格式化爲0x00 0x00 0x00 0x01
return：0 成功，1 失敗
int h264_format_start_code(const char *dst, const char *src, int type /* 0 for 001, 1 for 0001 */) {
FILE *ifile = fopen(src, "rb");
FILE *ofile = fopen(dst, "wb");
if (ifile && ofile) {
fseek(ifile, 0L, SEEK_END);
int size = ftell(ifile);
rewind(ifile);
unsigned char *ibuf = (unsigned char *)malloc(size * sizeof(unsigned char));
unsigned char *obuf = (unsigned char *)malloc(size * sizeof(unsigned char) * 2);
if (!ibuf || !obuf) return -1;
int r = fread(ibuf, 1, size, ifile);
if (r != size) return -1;
int x = 0;
int t = -1;
while (x < size - 4) {
if (ibuf[x + 0] == 0x00 && ibuf[x + 1] == 0x00) {
if (ibuf[x + 2] == 0x01) {
t = 0;
break;
}
else if (ibuf[x + 2] == 0x00 && ibuf[x + 3] == 0x01) {
t = 1;
break;
}
}
++x;
}
x = 0;
int y = 0;
if (t == -1 || type < 0 || type > 1) return -1;
if (t == type) {
while (x < size) {
obuf[x] = ibuf[x];
++x;
}
}
else {
if (type == 0) { // format 001
while (x < size - 4) {
if (ibuf[x + 0] == 0x00 && ibuf[x + 1] == 0x00 &&
ibuf[x + 2] == 0x00 && ibuf[x + 3] == 0x01) {
obuf[y++] = 0x00;
obuf[y++] = 0x00;
obuf[y++] = 0x01;
x += 4;
}
else {
obuf[y++] = ibuf[x++];
}
}
for (int i = 0; i < 4; i++)
obuf[y++] = ibuf[x++];
}
else { // format 0001
while (x < size - 3) {
if (ibuf[x + 0] == 0x00 && ibuf[x + 1] == 0x00 && ibuf[x + 2] == 0x01) {
obuf[y++] = 0x00;
obuf[y++] = 0x00;
obuf[y++] = 0x00;
obuf[y++] = 0x01;
x += 3;
}
else {
obuf[y++] = ibuf[x++];
}
}
for (int i = 0; i < 3; i++)
obuf[y++] = ibuf[x++];
}
}
fwrite(obuf, 1, y - 1, ofile);
free(ibuf);
free(obuf);
fclose(ifile);
fclose(ofile);
return 0;
}
return -1;
}