static int dts_probe(AVProbeData *p) { const uint8_t *buf, *bufp; uint32_t state = -1; int markers[4*16] = {0}; int exss_markers = 0, exss_nextpos = 0; int sum, max, pos, i; int64_t diff = 0; uint8_t hdr[12 + AV_INPUT_BUFFER_PADDING_SIZE] = { 0 }; for (pos = FFMIN(4096, p->buf_size); pos < p->buf_size - 2; pos += 2) { int marker, sample_blocks, sample_rate, sr_code, framesize; int lfe, wide_hdr, hdr_size; GetBitContext gb; bufp = buf = p->buf + pos; state = (state << 16) | bytestream_get_be16(&bufp); if (pos >= 4) diff += FFABS(((int16_t)AV_RL16(buf)) - (int16_t)AV_RL16(buf-4)); /* extension substream (EXSS) */ if (state == DCA_SYNCWORD_SUBSTREAM) { if (pos < exss_nextpos) continue; init_get_bits(&gb, buf - 2, 96); skip_bits_long(&gb, 42); wide_hdr = get_bits1(&gb); hdr_size = get_bits(&gb, 8 + 4 * wide_hdr) + 1; framesize = get_bits(&gb, 16 + 4 * wide_hdr) + 1; if (hdr_size & 3 || framesize & 3) continue; if (hdr_size < 16 || framesize < hdr_size) continue; if (pos - 2 + hdr_size > p->buf_size) continue; if (av_crc(av_crc_get_table(AV_CRC_16_CCITT), 0xffff, buf + 3, hdr_size - 5)) continue; if (pos == exss_nextpos) exss_markers++; else exss_markers = FFMAX(1, exss_markers - 1); exss_nextpos = pos + framesize; continue; } /* regular bitstream */ if (state == DCA_SYNCWORD_CORE_BE && (bytestream_get_be16(&bufp) & 0xFC00) == 0xFC00) marker = 0; else if (state == DCA_SYNCWORD_CORE_LE && (bytestream_get_be16(&bufp) & 0x00FC) == 0x00FC) marker = 1; /* 14 bits big-endian bitstream */ else if (state == DCA_SYNCWORD_CORE_14B_BE && (bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0) marker = 2; /* 14 bits little-endian bitstream */ else if (state == DCA_SYNCWORD_CORE_14B_LE && (bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007) marker = 3; else continue; if (avpriv_dca_convert_bitstream(buf-2, 12, hdr, 12) < 0) continue; init_get_bits(&gb, hdr, 96); skip_bits_long(&gb, 39); sample_blocks = get_bits(&gb, 7) + 1; if (sample_blocks < 8) continue; framesize = get_bits(&gb, 14) + 1; if (framesize < 95) continue; skip_bits(&gb, 6); sr_code = get_bits(&gb, 4); sample_rate = avpriv_dca_sample_rates[sr_code]; if (sample_rate == 0) continue; get_bits(&gb, 5); if (get_bits(&gb, 1)) continue; skip_bits_long(&gb, 9); lfe = get_bits(&gb, 2); if (lfe > 2) continue; marker += 4* sr_code; markers[marker] ++; } if (exss_markers > 3) return AVPROBE_SCORE_EXTENSION + 1; sum = max = 0; for (i=0; i<FF_ARRAY_ELEMS(markers); i++) { sum += markers[i]; if (markers[max] < markers[i]) max = i; } if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 && markers[max] * 4 > sum * 3 && diff / p->buf_size > 200) return AVPROBE_SCORE_EXTENSION + 1; return 0; }