blob: f7288376f62ff9a88569a78605265c7acb61a714
1 | /* |
2 | * IEC 61937 demuxer |
3 | * Copyright (c) 2010 Anssi Hannula <anssi.hannula at iki.fi> |
4 | * |
5 | * This file is part of FFmpeg. |
6 | * |
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. |
11 | * |
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. |
16 | * |
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 |
20 | */ |
21 | |
22 | /** |
23 | * @file |
24 | * IEC 61937 demuxer, used for compressed data in S/PDIF |
25 | * @author Anssi Hannula |
26 | */ |
27 | |
28 | #include "avformat.h" |
29 | #include "spdif.h" |
30 | #include "libavcodec/ac3.h" |
31 | #include "libavcodec/aacadtsdec.h" |
32 | |
33 | static int spdif_get_offset_and_codec(AVFormatContext *s, |
34 | enum IEC61937DataType data_type, |
35 | const char *buf, int *offset, |
36 | enum AVCodecID *codec) |
37 | { |
38 | AACADTSHeaderInfo aac_hdr; |
39 | GetBitContext gbc; |
40 | |
41 | switch (data_type & 0xff) { |
42 | case IEC61937_AC3: |
43 | *offset = AC3_FRAME_SIZE << 2; |
44 | *codec = AV_CODEC_ID_AC3; |
45 | break; |
46 | case IEC61937_MPEG1_LAYER1: |
47 | *offset = spdif_mpeg_pkt_offset[1][0]; |
48 | *codec = AV_CODEC_ID_MP1; |
49 | break; |
50 | case IEC61937_MPEG1_LAYER23: |
51 | *offset = spdif_mpeg_pkt_offset[1][0]; |
52 | *codec = AV_CODEC_ID_MP3; |
53 | break; |
54 | case IEC61937_MPEG2_EXT: |
55 | *offset = 4608; |
56 | *codec = AV_CODEC_ID_MP3; |
57 | break; |
58 | case IEC61937_MPEG2_AAC: |
59 | init_get_bits(&gbc, buf, AAC_ADTS_HEADER_SIZE * 8); |
60 | if (avpriv_aac_parse_header(&gbc, &aac_hdr) < 0) { |
61 | if (s) /* be silent during a probe */ |
62 | av_log(s, AV_LOG_ERROR, "Invalid AAC packet in IEC 61937\n"); |
63 | return AVERROR_INVALIDDATA; |
64 | } |
65 | *offset = aac_hdr.samples << 2; |
66 | *codec = AV_CODEC_ID_AAC; |
67 | break; |
68 | case IEC61937_MPEG2_LAYER1_LSF: |
69 | *offset = spdif_mpeg_pkt_offset[0][0]; |
70 | *codec = AV_CODEC_ID_MP1; |
71 | break; |
72 | case IEC61937_MPEG2_LAYER2_LSF: |
73 | *offset = spdif_mpeg_pkt_offset[0][1]; |
74 | *codec = AV_CODEC_ID_MP2; |
75 | break; |
76 | case IEC61937_MPEG2_LAYER3_LSF: |
77 | *offset = spdif_mpeg_pkt_offset[0][2]; |
78 | *codec = AV_CODEC_ID_MP3; |
79 | break; |
80 | case IEC61937_DTS1: |
81 | *offset = 2048; |
82 | *codec = AV_CODEC_ID_DTS; |
83 | break; |
84 | case IEC61937_DTS2: |
85 | *offset = 4096; |
86 | *codec = AV_CODEC_ID_DTS; |
87 | break; |
88 | case IEC61937_DTS3: |
89 | *offset = 8192; |
90 | *codec = AV_CODEC_ID_DTS; |
91 | break; |
92 | default: |
93 | if (s) { /* be silent during a probe */ |
94 | avpriv_request_sample(s, "Data type 0x%04x in IEC 61937", |
95 | data_type); |
96 | } |
97 | return AVERROR_PATCHWELCOME; |
98 | } |
99 | return 0; |
100 | } |
101 | |
102 | /* Largest offset between bursts we currently handle, i.e. AAC with |
103 | aac_hdr.samples = 4096 */ |
104 | #define SPDIF_MAX_OFFSET 16384 |
105 | |
106 | static int spdif_probe(AVProbeData *p) |
107 | { |
108 | enum AVCodecID codec; |
109 | return ff_spdif_probe (p->buf, p->buf_size, &codec); |
110 | } |
111 | |
112 | int ff_spdif_probe(const uint8_t *p_buf, int buf_size, enum AVCodecID *codec) |
113 | { |
114 | const uint8_t *buf = p_buf; |
115 | const uint8_t *probe_end = p_buf + FFMIN(2 * SPDIF_MAX_OFFSET, buf_size - 1); |
116 | const uint8_t *expected_code = buf + 7; |
117 | uint32_t state = 0; |
118 | int sync_codes = 0; |
119 | int consecutive_codes = 0; |
120 | int offset; |
121 | |
122 | for (; buf < probe_end; buf++) { |
123 | state = (state << 8) | *buf; |
124 | |
125 | if (state == (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2)) |
126 | && buf[1] < 0x37) { |
127 | sync_codes++; |
128 | |
129 | if (buf == expected_code) { |
130 | if (++consecutive_codes >= 2) |
131 | return AVPROBE_SCORE_MAX; |
132 | } else |
133 | consecutive_codes = 0; |
134 | |
135 | if (buf + 4 + AAC_ADTS_HEADER_SIZE > p_buf + buf_size) |
136 | break; |
137 | |
138 | /* continue probing to find more sync codes */ |
139 | probe_end = FFMIN(buf + SPDIF_MAX_OFFSET, p_buf + buf_size - 1); |
140 | |
141 | /* skip directly to the next sync code */ |
142 | if (!spdif_get_offset_and_codec(NULL, (buf[2] << 8) | buf[1], |
143 | &buf[5], &offset, codec)) { |
144 | if (buf + offset >= p_buf + buf_size) |
145 | break; |
146 | expected_code = buf + offset; |
147 | buf = expected_code - 7; |
148 | } |
149 | } |
150 | } |
151 | |
152 | if (!sync_codes) |
153 | return 0; |
154 | |
155 | if (sync_codes >= 6) |
156 | /* good amount of sync codes but with unexpected offsets */ |
157 | return AVPROBE_SCORE_EXTENSION; |
158 | |
159 | /* some sync codes were found */ |
160 | return AVPROBE_SCORE_EXTENSION / 4; |
161 | } |
162 | |
163 | static int spdif_read_header(AVFormatContext *s) |
164 | { |
165 | s->ctx_flags |= AVFMTCTX_NOHEADER; |
166 | return 0; |
167 | } |
168 | |
169 | int ff_spdif_read_packet(AVFormatContext *s, AVPacket *pkt) |
170 | { |
171 | AVIOContext *pb = s->pb; |
172 | enum IEC61937DataType data_type; |
173 | enum AVCodecID codec_id; |
174 | uint32_t state = 0; |
175 | int pkt_size_bits, offset, ret; |
176 | |
177 | while (state != (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))) { |
178 | state = (state << 8) | avio_r8(pb); |
179 | if (avio_feof(pb)) |
180 | return AVERROR_EOF; |
181 | } |
182 | |
183 | data_type = avio_rl16(pb); |
184 | pkt_size_bits = avio_rl16(pb); |
185 | |
186 | if (pkt_size_bits % 16) |
187 | avpriv_request_sample(s, "Packet not ending at a 16-bit boundary"); |
188 | |
189 | ret = av_new_packet(pkt, FFALIGN(pkt_size_bits, 16) >> 3); |
190 | if (ret) |
191 | return ret; |
192 | |
193 | pkt->pos = avio_tell(pb) - BURST_HEADER_SIZE; |
194 | |
195 | if (avio_read(pb, pkt->data, pkt->size) < pkt->size) { |
196 | av_packet_unref(pkt); |
197 | return AVERROR_EOF; |
198 | } |
199 | ff_spdif_bswap_buf16((uint16_t *)pkt->data, (uint16_t *)pkt->data, pkt->size >> 1); |
200 | |
201 | ret = spdif_get_offset_and_codec(s, data_type, pkt->data, |
202 | &offset, &codec_id); |
203 | if (ret) { |
204 | av_packet_unref(pkt); |
205 | return ret; |
206 | } |
207 | |
208 | /* skip over the padding to the beginning of the next frame */ |
209 | avio_skip(pb, offset - pkt->size - BURST_HEADER_SIZE); |
210 | |
211 | if (!s->nb_streams) { |
212 | /* first packet, create a stream */ |
213 | AVStream *st = avformat_new_stream(s, NULL); |
214 | if (!st) { |
215 | av_packet_unref(pkt); |
216 | return AVERROR(ENOMEM); |
217 | } |
218 | st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO; |
219 | st->codecpar->codec_id = codec_id; |
220 | } else if (codec_id != s->streams[0]->codecpar->codec_id) { |
221 | avpriv_report_missing_feature(s, "Codec change in IEC 61937"); |
222 | return AVERROR_PATCHWELCOME; |
223 | } |
224 | |
225 | if (!s->bit_rate && s->streams[0]->codecpar->sample_rate) |
226 | /* stream bitrate matches 16-bit stereo PCM bitrate for currently |
227 | supported codecs */ |
228 | s->bit_rate = 2 * 16 * s->streams[0]->codecpar->sample_rate; |
229 | |
230 | return 0; |
231 | } |
232 | |
233 | AVInputFormat ff_spdif_demuxer = { |
234 | .name = "spdif", |
235 | .long_name = NULL_IF_CONFIG_SMALL("IEC 61937 (compressed data in S/PDIF)"), |
236 | .read_probe = spdif_probe, |
237 | .read_header = spdif_read_header, |
238 | .read_packet = ff_spdif_read_packet, |
239 | .flags = AVFMT_GENERIC_INDEX, |
240 | }; |
241 |