| 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_free_packet(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_free_packet(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_free_packet(pkt); |
| 216 | return AVERROR(ENOMEM); |
| 217 | } |
| 218 | st->codec->codec_type = AVMEDIA_TYPE_AUDIO; |
| 219 | st->codec->codec_id = codec_id; |
| 220 | } else if (codec_id != s->streams[0]->codec->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]->codec->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]->codec->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 | }; |