3 * Copyright (c) 2011 Max Horn
5 * This file is part of FFmpeg.
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.
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.
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
30 * Demuxer for xWMA, a Microsoft audio container used by XAudio 2.
37 static int xwma_probe(AVProbeData
*p
)
39 if (!memcmp(p
->buf
, "RIFF", 4) && !memcmp(p
->buf
+ 8, "XWMA", 4))
40 return AVPROBE_SCORE_MAX
;
44 static int xwma_read_header(AVFormatContext
*s
)
48 uint32_t dpds_table_size
= 0;
49 uint32_t *dpds_table
= NULL
;
51 AVIOContext
*pb
= s
->pb
;
53 XWMAContext
*xwma
= s
->priv_data
;
56 /* The following code is mostly copied from wav.c, with some
60 /* check RIFF header */
62 if (tag
!= MKTAG('R', 'I', 'F', 'F'))
64 avio_rl32(pb
); /* file size */
66 if (tag
!= MKTAG('X', 'W', 'M', 'A'))
69 /* parse fmt header */
71 if (tag
!= MKTAG('f', 'm', 't', ' '))
74 st
= avformat_new_stream(s
, NULL
);
76 return AVERROR(ENOMEM
);
78 ret
= ff_get_wav_header(pb
, st
->codec
, size
);
81 st
->need_parsing
= AVSTREAM_PARSE_NONE
;
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
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
);
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.
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.
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.
104 avpriv_request_sample(s
, "Unexpected extradata (%d bytes)",
105 st
->codec
->extradata_size
);
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
);
112 /* setup extradata with our experimentally obtained value */
113 st
->codec
->extradata
[4] = 31;
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
;
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
;
128 /* set the sample rate */
129 avpriv_set_pts_info(st
, 64, 1, st
->codec
->sample_rate
);
131 /* parse the remaining RIFF chunks */
133 if (pb
->eof_reached
) {
137 /* read next chunk tag */
139 size
= avio_rl32(pb
);
140 if (tag
== MKTAG('d', 'a', 't', 'a')) {
141 /* We assume that the data chunk comes last. */
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."
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.
154 /* Error out if there is more than one dpds chunk. */
156 av_log(s
, AV_LOG_ERROR
, "two dpds chunks present\n");
157 ret
= AVERROR_INVALIDDATA
;
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
);
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
;
173 /* Allocate some temporary storage to keep the dpds data around.
174 * for processing later on.
176 dpds_table
= av_malloc(dpds_table_size
* sizeof(uint32_t));
178 return AVERROR(ENOMEM
);
181 for (i
= 0; i
< dpds_table_size
; ++i
) {
182 dpds_table
[i
] = avio_rl32(pb
);
189 /* Determine overall data length */
191 ret
= AVERROR_INVALIDDATA
;
195 xwma
->data_end
= INT64_MAX
;
197 xwma
->data_end
= avio_tell(pb
) + size
;
200 if (dpds_table
&& dpds_table_size
) {
202 const uint32_t bytes_per_sample
203 = (st
->codec
->channels
* st
->codec
->bits_per_coded_sample
) >> 3;
205 /* Estimate the duration from the total number of output bytes. */
206 const uint64_t total_decoded_bytes
= dpds_table
[dpds_table_size
- 1];
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
;
216 st
->duration
= total_decoded_bytes
/ bytes_per_sample
;
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
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.
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 */
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
245 st
->duration
= (size
<<3) * st
->codec
->sample_rate
/ st
->codec
->bit_rate
;
254 static int xwma_read_packet(AVFormatContext
*s
, AVPacket
*pkt
)
259 XWMAContext
*xwma
= s
->priv_data
;
263 left
= xwma
->data_end
- avio_tell(s
->pb
);
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
);
272 ret
= av_get_packet(s
->pb
, pkt
, size
);
276 pkt
->stream_index
= 0;
280 AVInputFormat ff_xwma_demuxer
= {
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
,