1/* 2 * xWMA demuxer 3 * Copyright (c) 2011 Max Horn 4 * 5 * This file is part of Libav. 6 * 7 * Libav 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 * Libav 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 Libav; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22#include <inttypes.h> 23 24#include "avformat.h" 25#include "internal.h" 26#include "riff.h" 27 28/* 29 * Demuxer for xWMA, a Microsoft audio container used by XAudio 2. 30 */ 31 32typedef struct { 33 int64_t data_end; 34} XWMAContext; 35 36static int xwma_probe(AVProbeData *p) 37{ 38 if (!memcmp(p->buf, "RIFF", 4) && !memcmp(p->buf + 8, "XWMA", 4)) 39 return AVPROBE_SCORE_MAX; 40 return 0; 41} 42 43static int xwma_read_header(AVFormatContext *s, AVFormatParameters *ap) 44{ 45 int64_t size, av_uninit(data_size); 46 int ret; 47 uint32_t dpds_table_size = 0; 48 uint32_t *dpds_table = 0; 49 unsigned int tag; 50 AVIOContext *pb = s->pb; 51 AVStream *st; 52 XWMAContext *xwma = s->priv_data; 53 int i; 54 55 /* The following code is mostly copied from wav.c, with some 56 * minor alterations. 57 */ 58 59 /* check RIFF header */ 60 tag = avio_rl32(pb); 61 if (tag != MKTAG('R', 'I', 'F', 'F')) 62 return -1; 63 avio_rl32(pb); /* file size */ 64 tag = avio_rl32(pb); 65 if (tag != MKTAG('X', 'W', 'M', 'A')) 66 return -1; 67 68 /* parse fmt header */ 69 tag = avio_rl32(pb); 70 if (tag != MKTAG('f', 'm', 't', ' ')) 71 return -1; 72 size = avio_rl32(pb); 73 st = avformat_new_stream(s, NULL); 74 if (!st) 75 return AVERROR(ENOMEM); 76 77 ret = ff_get_wav_header(pb, st->codec, size); 78 if (ret < 0) 79 return ret; 80 st->need_parsing = AVSTREAM_PARSE_NONE; 81 82 /* All xWMA files I have seen contained WMAv2 data. If there are files 83 * using WMA Pro or some other codec, then we need to figure out the right 84 * extradata for that. Thus, ask the user for feedback, but try to go on 85 * anyway. 86 */ 87 if (st->codec->codec_id != CODEC_ID_WMAV2) { 88 av_log(s, AV_LOG_WARNING, "unexpected codec (tag 0x04%x; id %d)\n", 89 st->codec->codec_tag, st->codec->codec_id); 90 av_log_ask_for_sample(s, NULL); 91 } else { 92 /* In all xWMA files I have seen, there is no extradata. But the WMA 93 * codecs require extradata, so we provide our own fake extradata. 94 * 95 * First, check that there really was no extradata in the header. If 96 * there was, then try to use it, after asking the user to provide a 97 * sample of this unusual file. 98 */ 99 if (st->codec->extradata_size != 0) { 100 /* Surprise, surprise: We *did* get some extradata. No idea 101 * if it will work, but just go on and try it, after asking 102 * the user for a sample. 103 */ 104 av_log(s, AV_LOG_WARNING, "unexpected extradata (%d bytes)\n", 105 st->codec->extradata_size); 106 av_log_ask_for_sample(s, NULL); 107 } else { 108 st->codec->extradata_size = 6; 109 st->codec->extradata = av_mallocz(6 + FF_INPUT_BUFFER_PADDING_SIZE); 110 if (!st->codec->extradata) 111 return AVERROR(ENOMEM); 112 113 /* setup extradata with our experimentally obtained value */ 114 st->codec->extradata[4] = 31; 115 } 116 } 117 118 if (!st->codec->channels) { 119 av_log(s, AV_LOG_WARNING, "Invalid channel count: %d\n", 120 st->codec->channels); 121 return AVERROR_INVALIDDATA; 122 } 123 if (!st->codec->bits_per_coded_sample) { 124 av_log(s, AV_LOG_WARNING, "Invalid bits_per_coded_sample: %d\n", 125 st->codec->bits_per_coded_sample); 126 return AVERROR_INVALIDDATA; 127 } 128 129 /* set the sample rate */ 130 avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate); 131 132 /* parse the remaining RIFF chunks */ 133 for (;;) { 134 if (pb->eof_reached) 135 return -1; 136 /* read next chunk tag */ 137 tag = avio_rl32(pb); 138 size = avio_rl32(pb); 139 if (tag == MKTAG('d', 'a', 't', 'a')) { 140 /* We assume that the data chunk comes last. */ 141 break; 142 } else if (tag == MKTAG('d','p','d','s')) { 143 /* Quoting the MSDN xWMA docs on the dpds chunk: "Contains the 144 * decoded packet cumulative data size array, each element is the 145 * number of bytes accumulated after the corresponding xWMA packet 146 * is decoded in order." 147 * 148 * Each packet has size equal to st->codec->block_align, which in 149 * all cases I saw so far was always 2230. Thus, we can use the 150 * dpds data to compute a seeking index. 151 */ 152 153 /* Error out if there is more than one dpds chunk. */ 154 if (dpds_table) { 155 av_log(s, AV_LOG_ERROR, "two dpds chunks present\n"); 156 return -1; 157 } 158 159 /* Compute the number of entries in the dpds chunk. */ 160 if (size & 3) { /* Size should be divisible by four */ 161 av_log(s, AV_LOG_WARNING, 162 "dpds chunk size %"PRId64" not divisible by 4\n", size); 163 } 164 dpds_table_size = size / 4; 165 if (dpds_table_size == 0 || dpds_table_size >= INT_MAX / 4) { 166 av_log(s, AV_LOG_ERROR, 167 "dpds chunk size %"PRId64" invalid\n", size); 168 return -1; 169 } 170 171 /* Allocate some temporary storage to keep the dpds data around. 172 * for processing later on. 173 */ 174 dpds_table = av_malloc(dpds_table_size * sizeof(uint32_t)); 175 if (!dpds_table) { 176 return AVERROR(ENOMEM); 177 } 178 179 for (i = 0; i < dpds_table_size; ++i) { 180 dpds_table[i] = avio_rl32(pb); 181 size -= 4; 182 } 183 } 184 avio_skip(pb, size); 185 } 186 187 /* Determine overall data length */ 188 if (size < 0) 189 return -1; 190 if (!size) { 191 xwma->data_end = INT64_MAX; 192 } else 193 xwma->data_end = avio_tell(pb) + size; 194 195 196 if (dpds_table && dpds_table_size) { 197 int64_t cur_pos; 198 const uint32_t bytes_per_sample 199 = (st->codec->channels * st->codec->bits_per_coded_sample) >> 3; 200 201 /* Estimate the duration from the total number of output bytes. */ 202 const uint64_t total_decoded_bytes = dpds_table[dpds_table_size - 1]; 203 st->duration = total_decoded_bytes / bytes_per_sample; 204 205 /* Use the dpds data to build a seek table. We can only do this after 206 * we know the offset to the data chunk, as we need that to determine 207 * the actual offset to each input block. 208 * Note: If we allowed ourselves to assume that the data chunk always 209 * follows immediately after the dpds block, we could of course guess 210 * the data block's start offset already while reading the dpds chunk. 211 * I decided against that, just in case other chunks ever are 212 * discovered. 213 */ 214 cur_pos = avio_tell(pb); 215 for (i = 0; i < dpds_table_size; ++i) { 216 /* From the number of output bytes that would accumulate in the 217 * output buffer after decoding the first (i+1) packets, we compute 218 * an offset / timestamp pair. 219 */ 220 av_add_index_entry(st, 221 cur_pos + (i+1) * st->codec->block_align, /* pos */ 222 dpds_table[i] / bytes_per_sample, /* timestamp */ 223 st->codec->block_align, /* size */ 224 0, /* duration */ 225 AVINDEX_KEYFRAME); 226 } 227 } else if (st->codec->bit_rate) { 228 /* No dpds chunk was present (or only an empty one), so estimate 229 * the total duration using the average bits per sample and the 230 * total data length. 231 */ 232 st->duration = (size<<3) * st->codec->sample_rate / st->codec->bit_rate; 233 } 234 235 av_free(dpds_table); 236 237 return 0; 238} 239 240static int xwma_read_packet(AVFormatContext *s, AVPacket *pkt) 241{ 242 int ret, size; 243 int64_t left; 244 AVStream *st; 245 XWMAContext *xwma = s->priv_data; 246 247 st = s->streams[0]; 248 249 left = xwma->data_end - avio_tell(s->pb); 250 if (left <= 0) { 251 return AVERROR_EOF; 252 } 253 254 /* read a single block; the default block size is 2230. */ 255 size = (st->codec->block_align > 1) ? st->codec->block_align : 2230; 256 size = FFMIN(size, left); 257 258 ret = av_get_packet(s->pb, pkt, size); 259 if (ret < 0) 260 return ret; 261 262 pkt->stream_index = 0; 263 return ret; 264} 265 266AVInputFormat ff_xwma_demuxer = { 267 .name = "xwma", 268 .long_name = NULL_IF_CONFIG_SMALL("Microsoft xWMA"), 269 .priv_data_size = sizeof(XWMAContext), 270 .read_probe = xwma_probe, 271 .read_header = xwma_read_header, 272 .read_packet = xwma_read_packet, 273}; 274