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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 XWMAContext {
34     int64_t data_end;
35 } XWMAContext;
36 
xwma_probe(const AVProbeData * p)37 static int xwma_probe(const 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 
xwma_read_header(AVFormatContext * s)44 static int xwma_read_header(AVFormatContext *s)
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 AVERROR_INVALIDDATA;
64     avio_rl32(pb); /* file size */
65     tag = avio_rl32(pb);
66     if (tag != MKTAG('X', 'W', 'M', 'A'))
67         return AVERROR_INVALIDDATA;
68 
69     /* parse fmt header */
70     tag = avio_rl32(pb);
71     if (tag != MKTAG('f', 'm', 't', ' '))
72         return AVERROR_INVALIDDATA;
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(s, pb, st->codecpar, size, 0);
79     if (ret < 0)
80         return ret;
81     st->need_parsing = AVSTREAM_PARSE_NONE;
82 
83     /* XWMA encoder only allows a few channel/sample rate/bitrate combinations,
84      * but some create identical files with fake bitrate (1ch 22050hz at
85      * 20/48/192kbps are all 20kbps, with the exact same codec data).
86      * Decoder needs correct bitrate to work, so it's normalized here. */
87     if (st->codecpar->codec_id == AV_CODEC_ID_WMAV2) {
88         int ch = st->codecpar->channels;
89         int sr = st->codecpar->sample_rate;
90         int br = st->codecpar->bit_rate;
91 
92         if (ch == 1) {
93             if (sr == 22050 && (br==48000 || br==192000))
94                 br = 20000;
95             else if (sr == 32000 && (br==48000 || br==192000))
96                 br = 20000;
97             else if (sr == 44100 && (br==96000 || br==192000))
98                 br = 48000;
99         }
100         else if (ch == 2) {
101             if (sr == 22050 && (br==48000 || br==192000))
102                 br = 32000;
103             else if (sr == 32000 && (br==192000))
104                 br = 48000;
105         }
106 
107         st->codecpar->bit_rate = br;
108     }
109 
110     /* Normally xWMA can only contain WMAv2 with 1/2 channels,
111      * and WMAPRO with 6 channels. */
112     if (st->codecpar->codec_id != AV_CODEC_ID_WMAV2 &&
113         st->codecpar->codec_id != AV_CODEC_ID_WMAPRO) {
114         avpriv_request_sample(s, "Unexpected codec (tag %s; id %d)",
115                               av_fourcc2str(st->codecpar->codec_tag),
116                               st->codecpar->codec_id);
117     } else {
118         /* xWMA shouldn't have extradata. But the WMA codecs require it,
119          * so we provide our own fake extradata.
120          *
121          * First, check that there really was no extradata in the header. If
122          * there was, then try to use it, after asking the user to provide a
123          * sample of this unusual file.
124          */
125         if (st->codecpar->extradata_size != 0) {
126             /* Surprise, surprise: We *did* get some extradata. No idea
127              * if it will work, but just go on and try it, after asking
128              * the user for a sample.
129              */
130             avpriv_request_sample(s, "Unexpected extradata (%d bytes)",
131                                   st->codecpar->extradata_size);
132         } else if (st->codecpar->codec_id == AV_CODEC_ID_WMAPRO) {
133             if ((ret = ff_alloc_extradata(st->codecpar, 18)) < 0)
134                 return ret;
135 
136             memset(st->codecpar->extradata, 0, st->codecpar->extradata_size);
137             st->codecpar->extradata[ 0] = st->codecpar->bits_per_coded_sample;
138             st->codecpar->extradata[14] = 224;
139         } else {
140             if ((ret = ff_alloc_extradata(st->codecpar, 6)) < 0)
141                 return ret;
142 
143             memset(st->codecpar->extradata, 0, st->codecpar->extradata_size);
144             /* setup extradata with our experimentally obtained value */
145             st->codecpar->extradata[4] = 31;
146         }
147     }
148 
149     if (!st->codecpar->channels) {
150         av_log(s, AV_LOG_WARNING, "Invalid channel count: %d\n",
151                st->codecpar->channels);
152         return AVERROR_INVALIDDATA;
153     }
154     if (!st->codecpar->bits_per_coded_sample) {
155         av_log(s, AV_LOG_WARNING, "Invalid bits_per_coded_sample: %d\n",
156                st->codecpar->bits_per_coded_sample);
157         return AVERROR_INVALIDDATA;
158     }
159 
160     /* set the sample rate */
161     avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
162 
163     /* parse the remaining RIFF chunks */
164     for (;;) {
165         if (pb->eof_reached) {
166             ret = AVERROR_EOF;
167             goto fail;
168         }
169         /* read next chunk tag */
170         tag = avio_rl32(pb);
171         size = avio_rl32(pb);
172         if (tag == MKTAG('d', 'a', 't', 'a')) {
173             /* We assume that the data chunk comes last. */
174             break;
175         } else if (tag == MKTAG('d','p','d','s')) {
176             /* Quoting the MSDN xWMA docs on the dpds chunk: "Contains the
177              * decoded packet cumulative data size array, each element is the
178              * number of bytes accumulated after the corresponding xWMA packet
179              * is decoded in order."
180              *
181              * Each packet has size equal to st->codecpar->block_align, which in
182              * all cases I saw so far was always 2230. Thus, we can use the
183              * dpds data to compute a seeking index.
184              */
185 
186             /* Error out if there is more than one dpds chunk. */
187             if (dpds_table) {
188                 av_log(s, AV_LOG_ERROR, "two dpds chunks present\n");
189                 ret = AVERROR_INVALIDDATA;
190                 goto fail;
191             }
192 
193             /* Compute the number of entries in the dpds chunk. */
194             if (size & 3) {  /* Size should be divisible by four */
195                 av_log(s, AV_LOG_WARNING,
196                        "dpds chunk size %"PRId64" not divisible by 4\n", size);
197             }
198             dpds_table_size = size / 4;
199             if (dpds_table_size == 0 || dpds_table_size >= INT_MAX / 4) {
200                 av_log(s, AV_LOG_ERROR,
201                        "dpds chunk size %"PRId64" invalid\n", size);
202                 return AVERROR_INVALIDDATA;
203             }
204 
205             /* Allocate some temporary storage to keep the dpds data around.
206              * for processing later on.
207              */
208             dpds_table = av_malloc_array(dpds_table_size, sizeof(uint32_t));
209             if (!dpds_table) {
210                 return AVERROR(ENOMEM);
211             }
212 
213             for (i = 0; i < dpds_table_size; ++i) {
214                 if (avio_feof(pb)) {
215                     ret = AVERROR_INVALIDDATA;
216                     goto fail;
217                 }
218                 dpds_table[i] = avio_rl32(pb);
219                 size -= 4;
220             }
221         }
222         avio_skip(pb, size);
223     }
224 
225     /* Determine overall data length */
226     if (size < 0) {
227         ret = AVERROR_INVALIDDATA;
228         goto fail;
229     }
230     if (!size) {
231         xwma->data_end = INT64_MAX;
232     } else
233         xwma->data_end = avio_tell(pb) + size;
234 
235 
236     if (dpds_table && dpds_table_size) {
237         int64_t cur_pos;
238         const uint32_t bytes_per_sample
239                 = (st->codecpar->channels * st->codecpar->bits_per_coded_sample) >> 3;
240 
241         /* Estimate the duration from the total number of output bytes. */
242         const uint64_t total_decoded_bytes = dpds_table[dpds_table_size - 1];
243 
244         if (!bytes_per_sample) {
245             av_log(s, AV_LOG_ERROR,
246                    "Invalid bits_per_coded_sample %d for %d channels\n",
247                    st->codecpar->bits_per_coded_sample, st->codecpar->channels);
248             ret = AVERROR_INVALIDDATA;
249             goto fail;
250         }
251 
252         st->duration = total_decoded_bytes / bytes_per_sample;
253 
254         /* Use the dpds data to build a seek table.  We can only do this after
255          * we know the offset to the data chunk, as we need that to determine
256          * the actual offset to each input block.
257          * Note: If we allowed ourselves to assume that the data chunk always
258          * follows immediately after the dpds block, we could of course guess
259          * the data block's start offset already while reading the dpds chunk.
260          * I decided against that, just in case other chunks ever are
261          * discovered.
262          */
263         cur_pos = avio_tell(pb);
264         for (i = 0; i < dpds_table_size; ++i) {
265             /* From the number of output bytes that would accumulate in the
266              * output buffer after decoding the first (i+1) packets, we compute
267              * an offset / timestamp pair.
268              */
269             av_add_index_entry(st,
270                                cur_pos + (i+1) * st->codecpar->block_align, /* pos */
271                                dpds_table[i] / bytes_per_sample,            /* timestamp */
272                                st->codecpar->block_align,                   /* size */
273                                0,                                           /* duration */
274                                AVINDEX_KEYFRAME);
275         }
276     } else if (st->codecpar->bit_rate) {
277         /* No dpds chunk was present (or only an empty one), so estimate
278          * the total duration using the average bits per sample and the
279          * total data length.
280          */
281         st->duration = (size<<3) * st->codecpar->sample_rate / st->codecpar->bit_rate;
282     }
283 
284 fail:
285     av_free(dpds_table);
286 
287     return ret;
288 }
289 
xwma_read_packet(AVFormatContext * s,AVPacket * pkt)290 static int xwma_read_packet(AVFormatContext *s, AVPacket *pkt)
291 {
292     int ret, size;
293     int64_t left;
294     AVStream *st;
295     XWMAContext *xwma = s->priv_data;
296 
297     st = s->streams[0];
298 
299     left = xwma->data_end - avio_tell(s->pb);
300     if (left <= 0) {
301         return AVERROR_EOF;
302     }
303 
304     /* read a single block; the default block size is 2230. */
305     size = (st->codecpar->block_align > 1) ? st->codecpar->block_align : 2230;
306     size = FFMIN(size, left);
307 
308     ret  = av_get_packet(s->pb, pkt, size);
309     if (ret < 0)
310         return ret;
311 
312     pkt->stream_index = 0;
313     return ret;
314 }
315 
316 AVInputFormat ff_xwma_demuxer = {
317     .name           = "xwma",
318     .long_name      = NULL_IF_CONFIG_SMALL("Microsoft xWMA"),
319     .priv_data_size = sizeof(XWMAContext),
320     .read_probe     = xwma_probe,
321     .read_header    = xwma_read_header,
322     .read_packet    = xwma_read_packet,
323 };
324