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xwma.c
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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 
33 typedef struct {
34  int64_t data_end;
35 } XWMAContext;
36 
37 static 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 
45 {
46  int64_t size;
47  int ret = 0;
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, 0);
79  if (ret < 0)
80  return ret;
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;
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",
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 fail;
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 fail;
159  }
160 
161  /* Compute the number of entries in the dpds chunk. */
162  if (size & 3) { /* Size should be divisible by four */
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 fail;
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",
212  ret = AVERROR_INVALIDDATA;
213  goto fail;
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  */
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 */
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 
248 fail:
249  av_free(dpds_table);
250 
251  return ret;
252 }
253 
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 
281  .name = "xwma",
282  .long_name = NULL_IF_CONFIG_SMALL("Microsoft xWMA"),
283  .priv_data_size = sizeof(XWMAContext),
287 };