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4349 | Serge | 1 | /* |
2 | * xWMA demuxer |
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3 | * Copyright (c) 2011 Max Horn |
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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 | #include |
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23 | |||
24 | #include "avformat.h" |
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25 | #include "internal.h" |
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26 | #include "riff.h" |
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27 | |||
28 | /* |
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29 | * Demuxer for xWMA, a Microsoft audio container used by XAudio 2. |
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30 | */ |
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31 | |||
32 | typedef struct { |
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33 | int64_t data_end; |
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34 | } XWMAContext; |
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35 | |||
36 | static int xwma_probe(AVProbeData *p) |
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37 | { |
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38 | if (!memcmp(p->buf, "RIFF", 4) && !memcmp(p->buf + 8, "XWMA", 4)) |
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39 | return AVPROBE_SCORE_MAX; |
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40 | return 0; |
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41 | } |
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42 | |||
43 | static int xwma_read_header(AVFormatContext *s) |
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44 | { |
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45 | int64_t size; |
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46 | int ret; |
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47 | uint32_t dpds_table_size = 0; |
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48 | uint32_t *dpds_table = 0; |
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49 | unsigned int tag; |
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50 | AVIOContext *pb = s->pb; |
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51 | AVStream *st; |
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52 | XWMAContext *xwma = s->priv_data; |
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53 | int i; |
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54 | |||
55 | /* The following code is mostly copied from wav.c, with some |
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56 | * minor alterations. |
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57 | */ |
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58 | |||
59 | /* check RIFF header */ |
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60 | tag = avio_rl32(pb); |
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61 | if (tag != MKTAG('R', 'I', 'F', 'F')) |
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62 | return -1; |
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63 | avio_rl32(pb); /* file size */ |
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64 | tag = avio_rl32(pb); |
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65 | if (tag != MKTAG('X', 'W', 'M', 'A')) |
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66 | return -1; |
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67 | |||
68 | /* parse fmt header */ |
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69 | tag = avio_rl32(pb); |
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70 | if (tag != MKTAG('f', 'm', 't', ' ')) |
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71 | return -1; |
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72 | size = avio_rl32(pb); |
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73 | st = avformat_new_stream(s, NULL); |
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74 | if (!st) |
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75 | return AVERROR(ENOMEM); |
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76 | |||
77 | ret = ff_get_wav_header(pb, st->codec, size); |
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78 | if (ret < 0) |
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79 | return ret; |
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80 | st->need_parsing = AVSTREAM_PARSE_NONE; |
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81 | |||
82 | /* All xWMA files I have seen contained WMAv2 data. If there are files |
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83 | * using WMA Pro or some other codec, then we need to figure out the right |
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84 | * extradata for that. Thus, ask the user for feedback, but try to go on |
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85 | * anyway. |
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86 | */ |
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87 | if (st->codec->codec_id != AV_CODEC_ID_WMAV2) { |
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88 | avpriv_request_sample(s, "Unexpected codec (tag 0x04%x; id %d)", |
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89 | st->codec->codec_tag, st->codec->codec_id); |
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90 | } else { |
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91 | /* In all xWMA files I have seen, there is no extradata. But the WMA |
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92 | * codecs require extradata, so we provide our own fake extradata. |
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93 | * |
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94 | * First, check that there really was no extradata in the header. If |
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95 | * there was, then try to use it, after asking the user to provide a |
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96 | * sample of this unusual file. |
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97 | */ |
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98 | if (st->codec->extradata_size != 0) { |
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99 | /* Surprise, surprise: We *did* get some extradata. No idea |
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100 | * if it will work, but just go on and try it, after asking |
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101 | * the user for a sample. |
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102 | */ |
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103 | avpriv_request_sample(s, "Unexpected extradata (%d bytes)", |
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104 | st->codec->extradata_size); |
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105 | } else { |
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106 | st->codec->extradata_size = 6; |
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107 | st->codec->extradata = av_mallocz(6 + FF_INPUT_BUFFER_PADDING_SIZE); |
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108 | if (!st->codec->extradata) |
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109 | return AVERROR(ENOMEM); |
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110 | |||
111 | /* setup extradata with our experimentally obtained value */ |
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112 | st->codec->extradata[4] = 31; |
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113 | } |
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114 | } |
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115 | |||
116 | if (!st->codec->channels) { |
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117 | av_log(s, AV_LOG_WARNING, "Invalid channel count: %d\n", |
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118 | st->codec->channels); |
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119 | return AVERROR_INVALIDDATA; |
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120 | } |
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121 | if (!st->codec->bits_per_coded_sample) { |
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122 | av_log(s, AV_LOG_WARNING, "Invalid bits_per_coded_sample: %d\n", |
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123 | st->codec->bits_per_coded_sample); |
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124 | return AVERROR_INVALIDDATA; |
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125 | } |
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126 | |||
127 | /* set the sample rate */ |
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128 | avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate); |
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129 | |||
130 | /* parse the remaining RIFF chunks */ |
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131 | for (;;) { |
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132 | if (pb->eof_reached) |
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133 | return -1; |
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134 | /* read next chunk tag */ |
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135 | tag = avio_rl32(pb); |
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136 | size = avio_rl32(pb); |
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137 | if (tag == MKTAG('d', 'a', 't', 'a')) { |
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138 | /* We assume that the data chunk comes last. */ |
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139 | break; |
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140 | } else if (tag == MKTAG('d','p','d','s')) { |
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141 | /* Quoting the MSDN xWMA docs on the dpds chunk: "Contains the |
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142 | * decoded packet cumulative data size array, each element is the |
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143 | * number of bytes accumulated after the corresponding xWMA packet |
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144 | * is decoded in order." |
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145 | * |
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146 | * Each packet has size equal to st->codec->block_align, which in |
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147 | * all cases I saw so far was always 2230. Thus, we can use the |
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148 | * dpds data to compute a seeking index. |
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149 | */ |
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150 | |||
151 | /* Error out if there is more than one dpds chunk. */ |
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152 | if (dpds_table) { |
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153 | av_log(s, AV_LOG_ERROR, "two dpds chunks present\n"); |
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154 | return -1; |
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155 | } |
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156 | |||
157 | /* Compute the number of entries in the dpds chunk. */ |
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158 | if (size & 3) { /* Size should be divisible by four */ |
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159 | av_log(s, AV_LOG_WARNING, |
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160 | "dpds chunk size %"PRId64" not divisible by 4\n", size); |
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161 | } |
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162 | dpds_table_size = size / 4; |
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163 | if (dpds_table_size == 0 || dpds_table_size >= INT_MAX / 4) { |
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164 | av_log(s, AV_LOG_ERROR, |
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165 | "dpds chunk size %"PRId64" invalid\n", size); |
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166 | return -1; |
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167 | } |
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168 | |||
169 | /* Allocate some temporary storage to keep the dpds data around. |
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170 | * for processing later on. |
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171 | */ |
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172 | dpds_table = av_malloc(dpds_table_size * sizeof(uint32_t)); |
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173 | if (!dpds_table) { |
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174 | return AVERROR(ENOMEM); |
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175 | } |
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176 | |||
177 | for (i = 0; i < dpds_table_size; ++i) { |
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178 | dpds_table[i] = avio_rl32(pb); |
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179 | size -= 4; |
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180 | } |
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181 | } |
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182 | avio_skip(pb, size); |
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183 | } |
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184 | |||
185 | /* Determine overall data length */ |
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186 | if (size < 0) |
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187 | return -1; |
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188 | if (!size) { |
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189 | xwma->data_end = INT64_MAX; |
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190 | } else |
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191 | xwma->data_end = avio_tell(pb) + size; |
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192 | |||
193 | |||
194 | if (dpds_table && dpds_table_size) { |
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195 | int64_t cur_pos; |
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196 | const uint32_t bytes_per_sample |
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197 | = (st->codec->channels * st->codec->bits_per_coded_sample) >> 3; |
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198 | |||
199 | /* Estimate the duration from the total number of output bytes. */ |
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200 | const uint64_t total_decoded_bytes = dpds_table[dpds_table_size - 1]; |
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201 | |||
202 | if (!bytes_per_sample) { |
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203 | av_log(s, AV_LOG_ERROR, |
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204 | "Invalid bits_per_coded_sample %d for %d channels\n", |
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205 | st->codec->bits_per_coded_sample, st->codec->channels); |
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206 | return AVERROR_INVALIDDATA; |
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207 | } |
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208 | |||
209 | st->duration = total_decoded_bytes / bytes_per_sample; |
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210 | |||
211 | /* Use the dpds data to build a seek table. We can only do this after |
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212 | * we know the offset to the data chunk, as we need that to determine |
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213 | * the actual offset to each input block. |
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214 | * Note: If we allowed ourselves to assume that the data chunk always |
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215 | * follows immediately after the dpds block, we could of course guess |
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216 | * the data block's start offset already while reading the dpds chunk. |
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217 | * I decided against that, just in case other chunks ever are |
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218 | * discovered. |
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219 | */ |
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220 | cur_pos = avio_tell(pb); |
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221 | for (i = 0; i < dpds_table_size; ++i) { |
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222 | /* From the number of output bytes that would accumulate in the |
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223 | * output buffer after decoding the first (i+1) packets, we compute |
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224 | * an offset / timestamp pair. |
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225 | */ |
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226 | av_add_index_entry(st, |
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227 | cur_pos + (i+1) * st->codec->block_align, /* pos */ |
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228 | dpds_table[i] / bytes_per_sample, /* timestamp */ |
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229 | st->codec->block_align, /* size */ |
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230 | 0, /* duration */ |
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231 | AVINDEX_KEYFRAME); |
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232 | } |
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233 | } else if (st->codec->bit_rate) { |
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234 | /* No dpds chunk was present (or only an empty one), so estimate |
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235 | * the total duration using the average bits per sample and the |
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236 | * total data length. |
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237 | */ |
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238 | st->duration = (size<<3) * st->codec->sample_rate / st->codec->bit_rate; |
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239 | } |
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240 | |||
241 | av_free(dpds_table); |
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242 | |||
243 | return 0; |
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244 | } |
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245 | |||
246 | static int xwma_read_packet(AVFormatContext *s, AVPacket *pkt) |
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247 | { |
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248 | int ret, size; |
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249 | int64_t left; |
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250 | AVStream *st; |
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251 | XWMAContext *xwma = s->priv_data; |
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252 | |||
253 | st = s->streams[0]; |
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254 | |||
255 | left = xwma->data_end - avio_tell(s->pb); |
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256 | if (left <= 0) { |
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257 | return AVERROR_EOF; |
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258 | } |
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259 | |||
260 | /* read a single block; the default block size is 2230. */ |
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261 | size = (st->codec->block_align > 1) ? st->codec->block_align : 2230; |
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262 | size = FFMIN(size, left); |
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263 | |||
264 | ret = av_get_packet(s->pb, pkt, size); |
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265 | if (ret < 0) |
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266 | return ret; |
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267 | |||
268 | pkt->stream_index = 0; |
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269 | return ret; |
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270 | } |
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271 | |||
272 | AVInputFormat ff_xwma_demuxer = { |
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273 | .name = "xwma", |
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274 | .long_name = NULL_IF_CONFIG_SMALL("Microsoft xWMA"), |
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275 | .priv_data_size = sizeof(XWMAContext), |
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276 | .read_probe = xwma_probe, |
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277 | .read_header = xwma_read_header, |
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278 | .read_packet = xwma_read_packet, |
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279 | };>=>3)><3)>>>>> |