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ffmpeg/libavformat/xwma.c

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/*
* xWMA demuxer
* Copyright (c) 2011 Max Horn
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <inttypes.h>
#include <stdint.h>
#include "avformat.h"
#include "internal.h"
#include "riff.h"
/*
* Demuxer for xWMA, a Microsoft audio container used by XAudio 2.
*/
typedef struct XWMAContext {
int64_t data_end;
} XWMAContext;
static int xwma_probe(AVProbeData *p)
{
if (!memcmp(p->buf, "RIFF", 4) && !memcmp(p->buf + 8, "XWMA", 4))
return AVPROBE_SCORE_MAX;
return 0;
}
static int xwma_read_header(AVFormatContext *s)
{
int64_t size;
int ret = 0;
uint32_t dpds_table_size = 0;
uint32_t *dpds_table = 0;
unsigned int tag;
AVIOContext *pb = s->pb;
AVStream *st;
XWMAContext *xwma = s->priv_data;
int i;
/* The following code is mostly copied from wav.c, with some
* minor alterations.
*/
/* check RIFF header */
tag = avio_rl32(pb);
if (tag != MKTAG('R', 'I', 'F', 'F'))
return -1;
avio_rl32(pb); /* file size */
tag = avio_rl32(pb);
if (tag != MKTAG('X', 'W', 'M', 'A'))
return -1;
/* parse fmt header */
tag = avio_rl32(pb);
if (tag != MKTAG('f', 'm', 't', ' '))
return -1;
size = avio_rl32(pb);
st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
ret = ff_get_wav_header(s, pb, st->codec, size);
if (ret < 0)
return ret;
st->need_parsing = AVSTREAM_PARSE_NONE;
/* All xWMA files I have seen contained WMAv2 data. If there are files
* using WMA Pro or some other codec, then we need to figure out the right
* extradata for that. Thus, ask the user for feedback, but try to go on
* anyway.
*/
if (st->codec->codec_id != AV_CODEC_ID_WMAV2) {
avpriv_request_sample(s, "Unexpected codec (tag 0x04%x; id %d)",
st->codec->codec_tag, st->codec->codec_id);
} else {
/* In all xWMA files I have seen, there is no extradata. But the WMA
* codecs require extradata, so we provide our own fake extradata.
*
* First, check that there really was no extradata in the header. If
* there was, then try to use it, after asking the user to provide a
* sample of this unusual file.
*/
if (st->codec->extradata_size != 0) {
/* Surprise, surprise: We *did* get some extradata. No idea
* if it will work, but just go on and try it, after asking
* the user for a sample.
*/
avpriv_request_sample(s, "Unexpected extradata (%d bytes)",
st->codec->extradata_size);
} else {
st->codec->extradata_size = 6;
st->codec->extradata = av_mallocz(6 + AV_INPUT_BUFFER_PADDING_SIZE);
if (!st->codec->extradata)
return AVERROR(ENOMEM);
/* setup extradata with our experimentally obtained value */
st->codec->extradata[4] = 31;
}
}
if (!st->codec->channels) {
av_log(s, AV_LOG_WARNING, "Invalid channel count: %d\n",
st->codec->channels);
return AVERROR_INVALIDDATA;
}
if (!st->codec->bits_per_coded_sample) {
av_log(s, AV_LOG_WARNING, "Invalid bits_per_coded_sample: %d\n",
st->codec->bits_per_coded_sample);
return AVERROR_INVALIDDATA;
}
/* set the sample rate */
avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
/* parse the remaining RIFF chunks */
for (;;) {
if (pb->eof_reached) {
ret = AVERROR_INVALIDDATA;
goto fail;
}
/* read next chunk tag */
tag = avio_rl32(pb);
size = avio_rl32(pb);
if (tag == MKTAG('d', 'a', 't', 'a')) {
/* We assume that the data chunk comes last. */
break;
} else if (tag == MKTAG('d','p','d','s')) {
/* Quoting the MSDN xWMA docs on the dpds chunk: "Contains the
* decoded packet cumulative data size array, each element is the
* number of bytes accumulated after the corresponding xWMA packet
* is decoded in order."
*
* Each packet has size equal to st->codec->block_align, which in
* all cases I saw so far was always 2230. Thus, we can use the
* dpds data to compute a seeking index.
*/
/* Error out if there is more than one dpds chunk. */
if (dpds_table) {
av_log(s, AV_LOG_ERROR, "two dpds chunks present\n");
ret = AVERROR_INVALIDDATA;
goto fail;
}
/* Compute the number of entries in the dpds chunk. */
if (size & 3) { /* Size should be divisible by four */
av_log(s, AV_LOG_WARNING,
"dpds chunk size %"PRId64" not divisible by 4\n", size);
}
dpds_table_size = size / 4;
if (dpds_table_size == 0 || dpds_table_size >= INT_MAX / 4) {
av_log(s, AV_LOG_ERROR,
"dpds chunk size %"PRId64" invalid\n", size);
return -1;
}
/* Allocate some temporary storage to keep the dpds data around.
* for processing later on.
*/
dpds_table = av_malloc(dpds_table_size * sizeof(uint32_t));
if (!dpds_table) {
return AVERROR(ENOMEM);
}
for (i = 0; i < dpds_table_size; ++i) {
dpds_table[i] = avio_rl32(pb);
size -= 4;
}
}
avio_skip(pb, size);
}
/* Determine overall data length */
if (size < 0) {
ret = AVERROR_INVALIDDATA;
goto fail;
}
if (!size) {
xwma->data_end = INT64_MAX;
} else
xwma->data_end = avio_tell(pb) + size;
if (dpds_table && dpds_table_size) {
int64_t cur_pos;
const uint32_t bytes_per_sample
= (st->codec->channels * st->codec->bits_per_coded_sample) >> 3;
/* Estimate the duration from the total number of output bytes. */
const uint64_t total_decoded_bytes = dpds_table[dpds_table_size - 1];
if (!bytes_per_sample) {
av_log(s, AV_LOG_ERROR,
"Invalid bits_per_coded_sample %d for %d channels\n",
st->codec->bits_per_coded_sample, st->codec->channels);
ret = AVERROR_INVALIDDATA;
goto fail;
}
st->duration = total_decoded_bytes / bytes_per_sample;
/* Use the dpds data to build a seek table. We can only do this after
* we know the offset to the data chunk, as we need that to determine
* the actual offset to each input block.
* Note: If we allowed ourselves to assume that the data chunk always
* follows immediately after the dpds block, we could of course guess
* the data block's start offset already while reading the dpds chunk.
* I decided against that, just in case other chunks ever are
* discovered.
*/
cur_pos = avio_tell(pb);
for (i = 0; i < dpds_table_size; ++i) {
/* From the number of output bytes that would accumulate in the
* output buffer after decoding the first (i+1) packets, we compute
* an offset / timestamp pair.
*/
av_add_index_entry(st,
cur_pos + (i+1) * st->codec->block_align, /* pos */
dpds_table[i] / bytes_per_sample, /* timestamp */
st->codec->block_align, /* size */
0, /* duration */
AVINDEX_KEYFRAME);
}
} else if (st->codec->bit_rate) {
/* No dpds chunk was present (or only an empty one), so estimate
* the total duration using the average bits per sample and the
* total data length.
*/
st->duration = (size<<3) * st->codec->sample_rate / st->codec->bit_rate;
}
fail:
av_free(dpds_table);
return ret;
}
static int xwma_read_packet(AVFormatContext *s, AVPacket *pkt)
{
int ret, size;
int64_t left;
AVStream *st;
XWMAContext *xwma = s->priv_data;
st = s->streams[0];
left = xwma->data_end - avio_tell(s->pb);
if (left <= 0) {
return AVERROR_EOF;
}
/* read a single block; the default block size is 2230. */
size = (st->codec->block_align > 1) ? st->codec->block_align : 2230;
size = FFMIN(size, left);
ret = av_get_packet(s->pb, pkt, size);
if (ret < 0)
return ret;
pkt->stream_index = 0;
return ret;
}
AVInputFormat ff_xwma_demuxer = {
.name = "xwma",
.long_name = NULL_IF_CONFIG_SMALL("Microsoft xWMA"),
.priv_data_size = sizeof(XWMAContext),
.read_probe = xwma_probe,
.read_header = xwma_read_header,
.read_packet = xwma_read_packet,
};
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