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