3 * Copyright (c) 2008 Benjamin Larsson
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 #include "libavutil/crc.h"
24 #include "libavcodec/bytestream.h"
25 #include "libavcodec/dca.h"
26 #include "libavcodec/dca_syncwords.h"
27 #include "libavcodec/get_bits.h"
32 static int dts_probe(AVProbeData *p)
34 const uint8_t *buf, *bufp;
36 int markers[4*16] = {0};
37 int exss_markers = 0, exss_nextpos = 0;
40 uint8_t hdr[12 + AV_INPUT_BUFFER_PADDING_SIZE] = { 0 };
42 for (pos = FFMIN(4096, p->buf_size); pos < p->buf_size - 2; pos += 2) {
43 int marker, sample_blocks, sample_rate, sr_code, framesize;
44 int lfe, wide_hdr, hdr_size;
47 bufp = buf = p->buf + pos;
48 state = (state << 16) | bytestream_get_be16(&bufp);
51 diff += FFABS(((int16_t)AV_RL16(buf)) - (int16_t)AV_RL16(buf-4));
53 /* extension substream (EXSS) */
54 if (state == DCA_SYNCWORD_SUBSTREAM) {
55 if (pos < exss_nextpos)
58 init_get_bits(&gb, buf - 2, 96);
59 skip_bits_long(&gb, 42);
61 wide_hdr = get_bits1(&gb);
62 hdr_size = get_bits(&gb, 8 + 4 * wide_hdr) + 1;
63 framesize = get_bits(&gb, 16 + 4 * wide_hdr) + 1;
64 if (hdr_size & 3 || framesize & 3)
66 if (hdr_size < 16 || framesize < hdr_size)
68 if (pos - 2 + hdr_size > p->buf_size)
70 if (av_crc(av_crc_get_table(AV_CRC_16_CCITT), 0xffff, buf + 3, hdr_size - 5))
73 if (pos == exss_nextpos)
76 exss_markers = FFMAX(1, exss_markers - 1);
77 exss_nextpos = pos + framesize;
81 /* regular bitstream */
82 if (state == DCA_SYNCWORD_CORE_BE &&
83 (bytestream_get_be16(&bufp) & 0xFC00) == 0xFC00)
85 else if (state == DCA_SYNCWORD_CORE_LE &&
86 (bytestream_get_be16(&bufp) & 0x00FC) == 0x00FC)
89 /* 14 bits big-endian bitstream */
90 else if (state == DCA_SYNCWORD_CORE_14B_BE &&
91 (bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
94 /* 14 bits little-endian bitstream */
95 else if (state == DCA_SYNCWORD_CORE_14B_LE &&
96 (bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
101 if (avpriv_dca_convert_bitstream(buf-2, 12, hdr, 12) < 0)
104 init_get_bits(&gb, hdr, 96);
105 skip_bits_long(&gb, 39);
107 sample_blocks = get_bits(&gb, 7) + 1;
108 if (sample_blocks < 8)
111 framesize = get_bits(&gb, 14) + 1;
116 sr_code = get_bits(&gb, 4);
117 sample_rate = avpriv_dca_sample_rates[sr_code];
118 if (sample_rate == 0)
122 if (get_bits(&gb, 1))
125 skip_bits_long(&gb, 9);
126 lfe = get_bits(&gb, 2);
130 marker += 4* sr_code;
135 if (exss_markers > 3)
136 return AVPROBE_SCORE_EXTENSION + 1;
139 for (i=0; i<FF_ARRAY_ELEMS(markers); i++) {
141 if (markers[max] < markers[i])
145 if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
146 markers[max] * 4 > sum * 3 &&
147 diff / p->buf_size > 200)
148 return AVPROBE_SCORE_EXTENSION + 1;
153 AVInputFormat ff_dts_demuxer = {
155 .long_name = NULL_IF_CONFIG_SMALL("raw DTS"),
156 .read_probe = dts_probe,
157 .read_header = ff_raw_audio_read_header,
158 .read_packet = ff_raw_read_partial_packet,
159 .flags = AVFMT_GENERIC_INDEX,
161 .raw_codec_id = AV_CODEC_ID_DTS,