From ad4c50347a46a67807925245e730f738cb4d6562 Mon Sep 17 00:00:00 2001 From: Max Horn Date: Tue, 12 Apr 2011 13:59:39 +0200 Subject: add xWMA demuxer Signed-off-by: Luca Barbato --- libavformat/xwma.c | 254 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 254 insertions(+) create mode 100644 libavformat/xwma.c (limited to 'libavformat/xwma.c') diff --git a/libavformat/xwma.c b/libavformat/xwma.c new file mode 100644 index 0000000000..4238054476 --- /dev/null +++ b/libavformat/xwma.c @@ -0,0 +1,254 @@ +/* + * 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 "avformat.h" +#include "riff.h" + +/* + * Demuxer for xWMA, a Microsoft audio container used by XAudio 2. + */ + +typedef struct { + 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, AVFormatParameters *ap) +{ + int64_t size, av_uninit(data_size); + 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 = av_new_stream(s, 0); + if (!st) + return AVERROR(ENOMEM); + + ff_get_wav_header(pb, st->codec, size); + 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 != CODEC_ID_WMAV2) { + av_log(s, AV_LOG_WARNING, "unexpected codec (tag 0x04%x; id %d)\n", + st->codec->codec_tag, st->codec->codec_id); + av_log_ask_for_sample(s, NULL); + } 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, after asking the 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. + */ + av_log(s, AV_LOG_WARNING, "unexpected extradata (%d bytes)\n", + st->codec->extradata_size); + av_log_ask_for_sample(s, NULL); + } else { + st->codec->extradata_size = 6; + st->codec->extradata = av_mallocz(6 + FF_INPUT_BUFFER_PADDING_SIZE); + if (!st->codec->extradata) + return AVERROR(ENOMEM); + + /* setup extradata with our experimentally obtained value */ + st->codec->extradata[4] = 31; + } + } + + /* set the sample rate */ + av_set_pts_info(st, 64, 1, st->codec->sample_rate); + + /* parse the remaining RIFF chunks */ + for (;;) { + if (pb->eof_reached) + return -1; + /* 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"); + return -1; + } + + /* 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) + return -1; + 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]; + 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; + } + + av_free(dpds_table); + + return 0; +} + +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 = { + "xwma", + NULL_IF_CONFIG_SMALL("Microsoft xWMA"), + sizeof(XWMAContext), + xwma_probe, + xwma_read_header, + xwma_read_packet, +}; -- cgit v1.2.3