1/* 2 * xWMA demuxer 3 * Copyright (c) 2011 Max Horn 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#include <inttypes.h> 23#include <stdint.h> 24 25#include "avformat.h" 26#include "internal.h" 27#include "riff.h" 28 29/* 30 * Demuxer for xWMA, a Microsoft audio container used by XAudio 2. 31 */ 32 33typedef struct { 34 int64_t data_end; 35} XWMAContext; 36 37static int xwma_probe(AVProbeData *p) 38{ 39 if (!memcmp(p->buf, "RIFF", 4) && !memcmp(p->buf + 8, "XWMA", 4)) 40 return AVPROBE_SCORE_MAX; 41 return 0; 42} 43 44static int xwma_read_header(AVFormatContext *s) 45{ 46 int64_t size; 47 int ret; 48 uint32_t dpds_table_size = 0; 49 uint32_t *dpds_table = NULL; 50 unsigned int tag; 51 AVIOContext *pb = s->pb; 52 AVStream *st; 53 XWMAContext *xwma = s->priv_data; 54 int i; 55 56 /* The following code is mostly copied from wav.c, with some 57 * minor alterations. 58 */ 59 60 /* check RIFF header */ 61 tag = avio_rl32(pb); 62 if (tag != MKTAG('R', 'I', 'F', 'F')) 63 return -1; 64 avio_rl32(pb); /* file size */ 65 tag = avio_rl32(pb); 66 if (tag != MKTAG('X', 'W', 'M', 'A')) 67 return -1; 68 69 /* parse fmt header */ 70 tag = avio_rl32(pb); 71 if (tag != MKTAG('f', 'm', 't', ' ')) 72 return -1; 73 size = avio_rl32(pb); 74 st = avformat_new_stream(s, NULL); 75 if (!st) 76 return AVERROR(ENOMEM); 77 78 ret = ff_get_wav_header(pb, st->codec, size); 79 if (ret < 0) 80 return ret; 81 st->need_parsing = AVSTREAM_PARSE_NONE; 82 83 /* All xWMA files I have seen contained WMAv2 data. If there are files 84 * using WMA Pro or some other codec, then we need to figure out the right 85 * extradata for that. Thus, ask the user for feedback, but try to go on 86 * anyway. 87 */ 88 if (st->codec->codec_id != AV_CODEC_ID_WMAV2) { 89 avpriv_request_sample(s, "Unexpected codec (tag 0x04%x; id %d)", 90 st->codec->codec_tag, st->codec->codec_id); 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 avpriv_request_sample(s, "Unexpected extradata (%d bytes)", 105 st->codec->extradata_size); 106 } else { 107 st->codec->extradata_size = 6; 108 st->codec->extradata = av_mallocz(6 + FF_INPUT_BUFFER_PADDING_SIZE); 109 if (!st->codec->extradata) 110 return AVERROR(ENOMEM); 111 112 /* setup extradata with our experimentally obtained value */ 113 st->codec->extradata[4] = 31; 114 } 115 } 116 117 if (!st->codec->channels) { 118 av_log(s, AV_LOG_WARNING, "Invalid channel count: %d\n", 119 st->codec->channels); 120 return AVERROR_INVALIDDATA; 121 } 122 if (!st->codec->bits_per_coded_sample) { 123 av_log(s, AV_LOG_WARNING, "Invalid bits_per_coded_sample: %d\n", 124 st->codec->bits_per_coded_sample); 125 return AVERROR_INVALIDDATA; 126 } 127 128 /* set the sample rate */ 129 avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate); 130 131 /* parse the remaining RIFF chunks */ 132 for (;;) { 133 if (pb->eof_reached) { 134 ret = AVERROR_EOF; 135 goto end; 136 } 137 /* read next chunk tag */ 138 tag = avio_rl32(pb); 139 size = avio_rl32(pb); 140 if (tag == MKTAG('d', 'a', 't', 'a')) { 141 /* We assume that the data chunk comes last. */ 142 break; 143 } else if (tag == MKTAG('d','p','d','s')) { 144 /* Quoting the MSDN xWMA docs on the dpds chunk: "Contains the 145 * decoded packet cumulative data size array, each element is the 146 * number of bytes accumulated after the corresponding xWMA packet 147 * is decoded in order." 148 * 149 * Each packet has size equal to st->codec->block_align, which in 150 * all cases I saw so far was always 2230. Thus, we can use the 151 * dpds data to compute a seeking index. 152 */ 153 154 /* Error out if there is more than one dpds chunk. */ 155 if (dpds_table) { 156 av_log(s, AV_LOG_ERROR, "two dpds chunks present\n"); 157 ret = AVERROR_INVALIDDATA; 158 goto end; 159 } 160 161 /* Compute the number of entries in the dpds chunk. */ 162 if (size & 3) { /* Size should be divisible by four */ 163 av_log(s, AV_LOG_WARNING, 164 "dpds chunk size %"PRId64" not divisible by 4\n", size); 165 } 166 dpds_table_size = size / 4; 167 if (dpds_table_size == 0 || dpds_table_size >= INT_MAX / 4) { 168 av_log(s, AV_LOG_ERROR, 169 "dpds chunk size %"PRId64" invalid\n", size); 170 return AVERROR_INVALIDDATA; 171 } 172 173 /* Allocate some temporary storage to keep the dpds data around. 174 * for processing later on. 175 */ 176 dpds_table = av_malloc(dpds_table_size * sizeof(uint32_t)); 177 if (!dpds_table) { 178 return AVERROR(ENOMEM); 179 } 180 181 for (i = 0; i < dpds_table_size; ++i) { 182 dpds_table[i] = avio_rl32(pb); 183 size -= 4; 184 } 185 } 186 avio_skip(pb, size); 187 } 188 189 /* Determine overall data length */ 190 if (size < 0) { 191 ret = AVERROR_INVALIDDATA; 192 goto end; 193 } 194 if (!size) { 195 xwma->data_end = INT64_MAX; 196 } else 197 xwma->data_end = avio_tell(pb) + size; 198 199 200 if (dpds_table && dpds_table_size) { 201 int64_t cur_pos; 202 const uint32_t bytes_per_sample 203 = (st->codec->channels * st->codec->bits_per_coded_sample) >> 3; 204 205 /* Estimate the duration from the total number of output bytes. */ 206 const uint64_t total_decoded_bytes = dpds_table[dpds_table_size - 1]; 207 208 if (!bytes_per_sample) { 209 av_log(s, AV_LOG_ERROR, 210 "Invalid bits_per_coded_sample %d for %d channels\n", 211 st->codec->bits_per_coded_sample, st->codec->channels); 212 ret = AVERROR_INVALIDDATA; 213 goto end; 214 } 215 216 st->duration = total_decoded_bytes / bytes_per_sample; 217 218 /* Use the dpds data to build a seek table. We can only do this after 219 * we know the offset to the data chunk, as we need that to determine 220 * the actual offset to each input block. 221 * Note: If we allowed ourselves to assume that the data chunk always 222 * follows immediately after the dpds block, we could of course guess 223 * the data block's start offset already while reading the dpds chunk. 224 * I decided against that, just in case other chunks ever are 225 * discovered. 226 */ 227 cur_pos = avio_tell(pb); 228 for (i = 0; i < dpds_table_size; ++i) { 229 /* From the number of output bytes that would accumulate in the 230 * output buffer after decoding the first (i+1) packets, we compute 231 * an offset / timestamp pair. 232 */ 233 av_add_index_entry(st, 234 cur_pos + (i+1) * st->codec->block_align, /* pos */ 235 dpds_table[i] / bytes_per_sample, /* timestamp */ 236 st->codec->block_align, /* size */ 237 0, /* duration */ 238 AVINDEX_KEYFRAME); 239 } 240 } else if (st->codec->bit_rate) { 241 /* No dpds chunk was present (or only an empty one), so estimate 242 * the total duration using the average bits per sample and the 243 * total data length. 244 */ 245 st->duration = (size<<3) * st->codec->sample_rate / st->codec->bit_rate; 246 } 247 248end: 249 av_free(dpds_table); 250 251 return ret; 252} 253 254static int xwma_read_packet(AVFormatContext *s, AVPacket *pkt) 255{ 256 int ret, size; 257 int64_t left; 258 AVStream *st; 259 XWMAContext *xwma = s->priv_data; 260 261 st = s->streams[0]; 262 263 left = xwma->data_end - avio_tell(s->pb); 264 if (left <= 0) { 265 return AVERROR_EOF; 266 } 267 268 /* read a single block; the default block size is 2230. */ 269 size = (st->codec->block_align > 1) ? st->codec->block_align : 2230; 270 size = FFMIN(size, left); 271 272 ret = av_get_packet(s->pb, pkt, size); 273 if (ret < 0) 274 return ret; 275 276 pkt->stream_index = 0; 277 return ret; 278} 279 280AVInputFormat ff_xwma_demuxer = { 281 .name = "xwma", 282 .long_name = NULL_IF_CONFIG_SMALL("Microsoft xWMA"), 283 .priv_data_size = sizeof(XWMAContext), 284 .read_probe = xwma_probe, 285 .read_header = xwma_read_header, 286 .read_packet = xwma_read_packet, 287}; 288