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
28 * Demuxer for xWMA, a Microsoft audio container used by XAudio 2.
35 static int xwma_probe(AVProbeData *p)
37 if (!memcmp(p->buf, "RIFF", 4) && !memcmp(p->buf + 8, "XWMA", 4))
38 return AVPROBE_SCORE_MAX;
42 static int xwma_read_header(AVFormatContext *s, AVFormatParameters *ap)
44 int64_t size, av_uninit(data_size);
46 uint32_t dpds_table_size = 0;
47 uint32_t *dpds_table = 0;
49 AVIOContext *pb = s->pb;
51 XWMAContext *xwma = s->priv_data;
54 /* The following code is mostly copied from wav.c, with some
58 /* check RIFF header */
60 if (tag != MKTAG('R', 'I', 'F', 'F'))
62 avio_rl32(pb); /* file size */
64 if (tag != MKTAG('X', 'W', 'M', 'A'))
67 /* parse fmt header */
69 if (tag != MKTAG('f', 'm', 't', ' '))
72 st = av_new_stream(s, 0);
74 return AVERROR(ENOMEM);
76 ret = ff_get_wav_header(pb, st->codec, size);
79 st->need_parsing = AVSTREAM_PARSE_NONE;
81 /* All xWMA files I have seen contained WMAv2 data. If there are files
82 * using WMA Pro or some other codec, then we need to figure out the right
83 * extradata for that. Thus, ask the user for feedback, but try to go on
86 if (st->codec->codec_id != CODEC_ID_WMAV2) {
87 av_log(s, AV_LOG_WARNING, "unexpected codec (tag 0x04%x; id %d)\n",
88 st->codec->codec_tag, st->codec->codec_id);
89 av_log_ask_for_sample(s, NULL);
91 /* In all xWMA files I have seen, there is no extradata. But the WMA
92 * codecs require extradata, so we provide our own fake extradata.
94 * First, check that there really was no extradata in the header. If
95 * there was, then try to use it, after asking the user to provide a
96 * sample of this unusual file.
98 if (st->codec->extradata_size != 0) {
99 /* Surprise, surprise: We *did* get some extradata. No idea
100 * if it will work, but just go on and try it, after asking
101 * the user for a sample.
103 av_log(s, AV_LOG_WARNING, "unexpected extradata (%d bytes)\n",
104 st->codec->extradata_size);
105 av_log_ask_for_sample(s, NULL);
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 /* set the sample rate */
118 av_set_pts_info(st, 64, 1, st->codec->sample_rate);
120 /* parse the remaining RIFF chunks */
124 /* read next chunk tag */
126 size = avio_rl32(pb);
127 if (tag == MKTAG('d', 'a', 't', 'a')) {
128 /* We assume that the data chunk comes last. */
130 } else if (tag == MKTAG('d','p','d','s')) {
131 /* Quoting the MSDN xWMA docs on the dpds chunk: "Contains the
132 * decoded packet cumulative data size array, each element is the
133 * number of bytes accumulated after the corresponding xWMA packet
134 * is decoded in order."
136 * Each packet has size equal to st->codec->block_align, which in
137 * all cases I saw so far was always 2230. Thus, we can use the
138 * dpds data to compute a seeking index.
141 /* Error out if there is more than one dpds chunk. */
143 av_log(s, AV_LOG_ERROR, "two dpds chunks present\n");
147 /* Compute the number of entries in the dpds chunk. */
148 if (size & 3) { /* Size should be divisible by four */
149 av_log(s, AV_LOG_WARNING,
150 "dpds chunk size %"PRId64" not divisible by 4\n", size);
152 dpds_table_size = size / 4;
153 if (dpds_table_size == 0 || dpds_table_size >= INT_MAX / 4) {
154 av_log(s, AV_LOG_ERROR,
155 "dpds chunk size %"PRId64" invalid\n", size);
159 /* Allocate some temporary storage to keep the dpds data around.
160 * for processing later on.
162 dpds_table = av_malloc(dpds_table_size * sizeof(uint32_t));
164 return AVERROR(ENOMEM);
167 for (i = 0; i < dpds_table_size; ++i) {
168 dpds_table[i] = avio_rl32(pb);
175 /* Determine overall data length */
179 xwma->data_end = INT64_MAX;
181 xwma->data_end = avio_tell(pb) + size;
184 if (dpds_table && dpds_table_size) {
186 const uint32_t bytes_per_sample
187 = (st->codec->channels * st->codec->bits_per_coded_sample) >> 3;
189 /* Estimate the duration from the total number of output bytes. */
190 const uint64_t total_decoded_bytes = dpds_table[dpds_table_size - 1];
191 st->duration = total_decoded_bytes / bytes_per_sample;
193 /* Use the dpds data to build a seek table. We can only do this after
194 * we know the offset to the data chunk, as we need that to determine
195 * the actual offset to each input block.
196 * Note: If we allowed ourselves to assume that the data chunk always
197 * follows immediately after the dpds block, we could of course guess
198 * the data block's start offset already while reading the dpds chunk.
199 * I decided against that, just in case other chunks ever are
202 cur_pos = avio_tell(pb);
203 for (i = 0; i < dpds_table_size; ++i) {
204 /* From the number of output bytes that would accumulate in the
205 * output buffer after decoding the first (i+1) packets, we compute
206 * an offset / timestamp pair.
208 av_add_index_entry(st,
209 cur_pos + (i+1) * st->codec->block_align, /* pos */
210 dpds_table[i] / bytes_per_sample, /* timestamp */
211 st->codec->block_align, /* size */
215 } else if (st->codec->bit_rate) {
216 /* No dpds chunk was present (or only an empty one), so estimate
217 * the total duration using the average bits per sample and the
220 st->duration = (size<<3) * st->codec->sample_rate / st->codec->bit_rate;
228 static int xwma_read_packet(AVFormatContext *s, AVPacket *pkt)
233 XWMAContext *xwma = s->priv_data;
237 left = xwma->data_end - avio_tell(s->pb);
242 /* read a single block; the default block size is 2230. */
243 size = (st->codec->block_align > 1) ? st->codec->block_align : 2230;
244 size = FFMIN(size, left);
246 ret = av_get_packet(s->pb, pkt, size);
250 pkt->stream_index = 0;
254 AVInputFormat ff_xwma_demuxer = {
256 NULL_IF_CONFIG_SMALL("Microsoft xWMA"),