int ff_h264_decode_extradata(H264Context *h, const uint8_t *buf, int size) { AVCodecContext *avctx = h->s.avctx; if (!buf || size <= 0) return -1; if (buf[0] == 1) { int i, cnt, nalsize; const unsigned char *p = buf; h->is_avc = 1; if (size < 7) { av_log(avctx, AV_LOG_ERROR, "avcC too short\n"); return -1; } /* sps and pps in the avcC always have length coded with 2 bytes, * so put a fake nal_length_size = 2 while parsing them */ h->nal_length_size = 2; // Decode sps from avcC cnt = *(p + 5) & 0x1f; // Number of sps p += 6; for (i = 0; i < cnt; i++) { nalsize = AV_RB16(p) + 2; if(nalsize > size - (p-buf)) return -1; if (decode_nal_units(h, p, nalsize) < 0) { av_log(avctx, AV_LOG_ERROR, "Decoding sps %d from avcC failed\n", i); return -1; } p += nalsize; } // Decode pps from avcC cnt = *(p++); // Number of pps for (i = 0; i < cnt; i++) { nalsize = AV_RB16(p) + 2; if(nalsize > size - (p-buf)) return -1; if (decode_nal_units(h, p, nalsize) < 0) { av_log(avctx, AV_LOG_ERROR, "Decoding pps %d from avcC failed\n", i); return -1; } p += nalsize; } // Now store right nal length size, that will be used to parse all other nals h->nal_length_size = (buf[4] & 0x03) + 1; } else { h->is_avc = 0; if (decode_nal_units(h, buf, size) < 0) return -1; } return size; }