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6148 | serge | 1 | /* |
2 | * IEC 61937 demuxer |
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3 | * Copyright (c) 2010 Anssi Hannula |
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4 | * |
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5 | * This file is part of FFmpeg. |
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6 | * |
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7 | * FFmpeg is free software; you can redistribute it and/or |
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8 | * modify it under the terms of the GNU Lesser General Public |
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9 | * License as published by the Free Software Foundation; either |
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10 | * version 2.1 of the License, or (at your option) any later version. |
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11 | * |
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12 | * FFmpeg is distributed in the hope that it will be useful, |
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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15 | * Lesser General Public License for more details. |
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16 | * |
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17 | * You should have received a copy of the GNU Lesser General Public |
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18 | * License along with FFmpeg; if not, write to the Free Software |
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19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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20 | */ |
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21 | |||
22 | /** |
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23 | * @file |
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24 | * IEC 61937 demuxer, used for compressed data in S/PDIF |
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25 | * @author Anssi Hannula |
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26 | */ |
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27 | |||
28 | #include "avformat.h" |
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29 | #include "spdif.h" |
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30 | #include "libavcodec/ac3.h" |
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31 | #include "libavcodec/aacadtsdec.h" |
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32 | |||
33 | static int spdif_get_offset_and_codec(AVFormatContext *s, |
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34 | enum IEC61937DataType data_type, |
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35 | const char *buf, int *offset, |
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36 | enum AVCodecID *codec) |
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37 | { |
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38 | AACADTSHeaderInfo aac_hdr; |
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39 | GetBitContext gbc; |
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40 | |||
41 | switch (data_type & 0xff) { |
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42 | case IEC61937_AC3: |
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43 | *offset = AC3_FRAME_SIZE << 2; |
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44 | *codec = AV_CODEC_ID_AC3; |
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45 | break; |
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46 | case IEC61937_MPEG1_LAYER1: |
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47 | *offset = spdif_mpeg_pkt_offset[1][0]; |
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48 | *codec = AV_CODEC_ID_MP1; |
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49 | break; |
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50 | case IEC61937_MPEG1_LAYER23: |
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51 | *offset = spdif_mpeg_pkt_offset[1][0]; |
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52 | *codec = AV_CODEC_ID_MP3; |
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53 | break; |
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54 | case IEC61937_MPEG2_EXT: |
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55 | *offset = 4608; |
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56 | *codec = AV_CODEC_ID_MP3; |
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57 | break; |
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58 | case IEC61937_MPEG2_AAC: |
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59 | init_get_bits(&gbc, buf, AAC_ADTS_HEADER_SIZE * 8); |
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60 | if (avpriv_aac_parse_header(&gbc, &aac_hdr) < 0) { |
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61 | if (s) /* be silent during a probe */ |
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62 | av_log(s, AV_LOG_ERROR, "Invalid AAC packet in IEC 61937\n"); |
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63 | return AVERROR_INVALIDDATA; |
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64 | } |
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65 | *offset = aac_hdr.samples << 2; |
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66 | *codec = AV_CODEC_ID_AAC; |
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67 | break; |
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68 | case IEC61937_MPEG2_LAYER1_LSF: |
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69 | *offset = spdif_mpeg_pkt_offset[0][0]; |
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70 | *codec = AV_CODEC_ID_MP1; |
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71 | break; |
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72 | case IEC61937_MPEG2_LAYER2_LSF: |
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73 | *offset = spdif_mpeg_pkt_offset[0][1]; |
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74 | *codec = AV_CODEC_ID_MP2; |
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75 | break; |
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76 | case IEC61937_MPEG2_LAYER3_LSF: |
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77 | *offset = spdif_mpeg_pkt_offset[0][2]; |
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78 | *codec = AV_CODEC_ID_MP3; |
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79 | break; |
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80 | case IEC61937_DTS1: |
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81 | *offset = 2048; |
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82 | *codec = AV_CODEC_ID_DTS; |
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83 | break; |
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84 | case IEC61937_DTS2: |
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85 | *offset = 4096; |
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86 | *codec = AV_CODEC_ID_DTS; |
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87 | break; |
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88 | case IEC61937_DTS3: |
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89 | *offset = 8192; |
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90 | *codec = AV_CODEC_ID_DTS; |
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91 | break; |
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92 | default: |
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93 | if (s) { /* be silent during a probe */ |
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94 | avpriv_request_sample(s, "Data type 0x%04x in IEC 61937", |
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95 | data_type); |
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96 | } |
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97 | return AVERROR_PATCHWELCOME; |
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98 | } |
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99 | return 0; |
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100 | } |
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101 | |||
102 | /* Largest offset between bursts we currently handle, i.e. AAC with |
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103 | aac_hdr.samples = 4096 */ |
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104 | #define SPDIF_MAX_OFFSET 16384 |
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105 | |||
106 | static int spdif_probe(AVProbeData *p) |
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107 | { |
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108 | enum AVCodecID codec; |
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109 | return ff_spdif_probe (p->buf, p->buf_size, &codec); |
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110 | } |
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111 | |||
112 | int ff_spdif_probe(const uint8_t *p_buf, int buf_size, enum AVCodecID *codec) |
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113 | { |
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114 | const uint8_t *buf = p_buf; |
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115 | const uint8_t *probe_end = p_buf + FFMIN(2 * SPDIF_MAX_OFFSET, buf_size - 1); |
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116 | const uint8_t *expected_code = buf + 7; |
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117 | uint32_t state = 0; |
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118 | int sync_codes = 0; |
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119 | int consecutive_codes = 0; |
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120 | int offset; |
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121 | |||
122 | for (; buf < probe_end; buf++) { |
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123 | state = (state << 8) | *buf; |
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124 | |||
125 | if (state == (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2)) |
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126 | && buf[1] < 0x37) { |
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127 | sync_codes++; |
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128 | |||
129 | if (buf == expected_code) { |
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130 | if (++consecutive_codes >= 2) |
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131 | return AVPROBE_SCORE_MAX; |
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132 | } else |
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133 | consecutive_codes = 0; |
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134 | |||
135 | if (buf + 4 + AAC_ADTS_HEADER_SIZE > p_buf + buf_size) |
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136 | break; |
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137 | |||
138 | /* continue probing to find more sync codes */ |
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139 | probe_end = FFMIN(buf + SPDIF_MAX_OFFSET, p_buf + buf_size - 1); |
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140 | |||
141 | /* skip directly to the next sync code */ |
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142 | if (!spdif_get_offset_and_codec(NULL, (buf[2] << 8) | buf[1], |
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143 | &buf[5], &offset, codec)) { |
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144 | if (buf + offset >= p_buf + buf_size) |
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145 | break; |
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146 | expected_code = buf + offset; |
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147 | buf = expected_code - 7; |
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148 | } |
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149 | } |
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150 | } |
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151 | |||
152 | if (!sync_codes) |
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153 | return 0; |
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154 | |||
155 | if (sync_codes >= 6) |
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156 | /* good amount of sync codes but with unexpected offsets */ |
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157 | return AVPROBE_SCORE_EXTENSION; |
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158 | |||
159 | /* some sync codes were found */ |
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160 | return AVPROBE_SCORE_EXTENSION / 4; |
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161 | } |
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162 | |||
163 | static int spdif_read_header(AVFormatContext *s) |
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164 | { |
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165 | s->ctx_flags |= AVFMTCTX_NOHEADER; |
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166 | return 0; |
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167 | } |
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168 | |||
169 | int ff_spdif_read_packet(AVFormatContext *s, AVPacket *pkt) |
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170 | { |
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171 | AVIOContext *pb = s->pb; |
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172 | enum IEC61937DataType data_type; |
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173 | enum AVCodecID codec_id; |
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174 | uint32_t state = 0; |
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175 | int pkt_size_bits, offset, ret; |
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176 | |||
177 | while (state != (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))) { |
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178 | state = (state << 8) | avio_r8(pb); |
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179 | if (url_feof(pb)) |
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180 | return AVERROR_EOF; |
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181 | } |
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182 | |||
183 | data_type = avio_rl16(pb); |
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184 | pkt_size_bits = avio_rl16(pb); |
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185 | |||
186 | if (pkt_size_bits % 16) |
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187 | avpriv_request_sample(s, "Packet not ending at a 16-bit boundary"); |
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188 | |||
189 | ret = av_new_packet(pkt, FFALIGN(pkt_size_bits, 16) >> 3); |
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190 | if (ret) |
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191 | return ret; |
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192 | |||
193 | pkt->pos = avio_tell(pb) - BURST_HEADER_SIZE; |
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194 | |||
195 | if (avio_read(pb, pkt->data, pkt->size) < pkt->size) { |
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196 | av_free_packet(pkt); |
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197 | return AVERROR_EOF; |
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198 | } |
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199 | ff_spdif_bswap_buf16((uint16_t *)pkt->data, (uint16_t *)pkt->data, pkt->size >> 1); |
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200 | |||
201 | ret = spdif_get_offset_and_codec(s, data_type, pkt->data, |
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202 | &offset, &codec_id); |
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203 | if (ret) { |
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204 | av_free_packet(pkt); |
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205 | return ret; |
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206 | } |
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207 | |||
208 | /* skip over the padding to the beginning of the next frame */ |
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209 | avio_skip(pb, offset - pkt->size - BURST_HEADER_SIZE); |
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210 | |||
211 | if (!s->nb_streams) { |
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212 | /* first packet, create a stream */ |
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213 | AVStream *st = avformat_new_stream(s, NULL); |
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214 | if (!st) { |
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215 | av_free_packet(pkt); |
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216 | return AVERROR(ENOMEM); |
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217 | } |
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218 | st->codec->codec_type = AVMEDIA_TYPE_AUDIO; |
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219 | st->codec->codec_id = codec_id; |
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220 | } else if (codec_id != s->streams[0]->codec->codec_id) { |
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221 | avpriv_report_missing_feature(s, "Codec change in IEC 61937"); |
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222 | return AVERROR_PATCHWELCOME; |
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223 | } |
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224 | |||
225 | if (!s->bit_rate && s->streams[0]->codec->sample_rate) |
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226 | /* stream bitrate matches 16-bit stereo PCM bitrate for currently |
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227 | supported codecs */ |
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228 | s->bit_rate = 2 * 16 * s->streams[0]->codec->sample_rate; |
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229 | |||
230 | return 0; |
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231 | } |
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232 | |||
233 | AVInputFormat ff_spdif_demuxer = { |
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234 | .name = "spdif", |
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235 | .long_name = NULL_IF_CONFIG_SMALL("IEC 61937 (compressed data in S/PDIF)"), |
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236 | .read_probe = spdif_probe, |
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237 | .read_header = spdif_read_header, |
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238 | .read_packet = ff_spdif_read_packet, |
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239 | .flags = AVFMT_GENERIC_INDEX, |
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240 | };>><>><>><>>><>><>>><>>><> |