Created
September 4, 2023 06:46
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Convert H.264 bistream from AVCC to ANNEXB format
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| #include <stdio.h> | |
| #include <string.h> | |
| #include <stdlib.h> | |
| #include <stdint.h> | |
| #define AVCC_HEADER_OFFSET 4 | |
| #define AVCC_NALU_LEN_UINT_SIZE_MINUS_1_MASK 0x3 | |
| #define AVCC_HEADER_SPS_CNT_OFFSET 5 | |
| #define SPS_CNT_MASK 0x1f | |
| #define START_CODE_SIZE 4 | |
| int main(int argc, char *argv[]) { | |
| int i = 0; | |
| const uint8_t start_code[] = {0, 0, 0, 1}; | |
| if (argc < 3) { | |
| printf("Invalid args\n"); | |
| return -1; | |
| } | |
| FILE *in_file = fopen(argv[1], "r"); | |
| if (!in_file) { | |
| printf("Failed to open %s\n", argv[1]); | |
| return -1; | |
| } | |
| fseek(in_file, 0, SEEK_END); | |
| int in_size = ftell(in_file); | |
| uint8_t *in_data = (uint8_t *) malloc(in_size + 1); | |
| uint8_t *pos = in_data + AVCC_HEADER_OFFSET; | |
| fseek(in_file, 0, SEEK_SET); | |
| fread(in_data, 1, in_size, in_file); | |
| fclose(in_file); | |
| FILE *out_file = fopen(argv[2], "wb"); | |
| int nalu_len_unit_size = (*pos) & AVCC_NALU_LEN_UINT_SIZE_MINUS_1_MASK + 1; | |
| pos++; | |
| int sps_cnt = (*pos) & SPS_CNT_MASK; | |
| pos++; | |
| printf("NALU len using %d bytes\n", nalu_len_unit_size); | |
| printf("SPS cnt %d\n", sps_cnt); | |
| for(i = 0; i < sps_cnt; i++) { | |
| int sps_len = (pos[0] << 8) + pos[1]; | |
| pos += 2; | |
| printf("SPS[%d], length %d\n", i, sps_len); | |
| fwrite(start_code, 1, START_CODE_SIZE, out_file); | |
| fwrite(pos, 1, sps_len, out_file); | |
| pos += sps_len; | |
| } | |
| int pps_cnt = *pos; | |
| pos++; | |
| printf("PPS cnt %d\n", pps_cnt); | |
| for (i = 0; i < pps_cnt; i++) { | |
| int pps_len = (pos[0] << 8) + pos[1]; | |
| pos += 2; | |
| printf("PPS[%d], length %d\n", i, pps_len); | |
| fwrite(start_code, 1, START_CODE_SIZE, out_file); | |
| fwrite(pos, 1, pps_len, out_file); | |
| pos += pps_len; | |
| } | |
| int read_len = pos - in_data + 1; | |
| uint32_t nalu_len = 0; | |
| while (read_len <= in_size) { | |
| for (i = 0; i < nalu_len_unit_size; i++) { | |
| nalu_len = nalu_len + (pos[i] << (8 * (nalu_len_unit_size - 1 - i))); | |
| } | |
| printf("nalu length 0x%x\n", nalu_len); | |
| pos += nalu_len_unit_size; | |
| fwrite(start_code, 1, START_CODE_SIZE, out_file); | |
| fwrite(pos, 1, nalu_len, out_file); | |
| pos += nalu_len; | |
| read_len = read_len + nalu_len_unit_size + nalu_len; | |
| nalu_len = 0; | |
| } | |
| fclose(out_file); | |
| free(in_data); | |
| } |
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