mirror of https://github.com/FFmpeg/FFmpeg.git
Max Horn
14 years ago
committed by
Luca Barbato
parent
0a962e61e9
commit
ad4c50347a
6 changed files with 260 additions and 1 deletions
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/*
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* xWMA demuxer |
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* Copyright (c) 2011 Max Horn |
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* |
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* This file is part of Libav. |
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* |
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* Libav is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* Libav is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with Libav; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include "avformat.h" |
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#include "riff.h" |
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/*
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* Demuxer for xWMA, a Microsoft audio container used by XAudio 2. |
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*/ |
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typedef struct { |
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int64_t data_end; |
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} XWMAContext; |
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static int xwma_probe(AVProbeData *p) |
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{ |
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if (!memcmp(p->buf, "RIFF", 4) && !memcmp(p->buf + 8, "XWMA", 4)) |
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return AVPROBE_SCORE_MAX; |
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return 0; |
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} |
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static int xwma_read_header(AVFormatContext *s, AVFormatParameters *ap) |
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{ |
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int64_t size, av_uninit(data_size); |
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uint32_t dpds_table_size = 0; |
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uint32_t *dpds_table = 0; |
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unsigned int tag; |
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AVIOContext *pb = s->pb; |
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AVStream *st; |
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XWMAContext *xwma = s->priv_data; |
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int i; |
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/* The following code is mostly copied from wav.c, with some
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* minor alterations. |
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*/ |
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/* check RIFF header */ |
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tag = avio_rl32(pb); |
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if (tag != MKTAG('R', 'I', 'F', 'F')) |
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return -1; |
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avio_rl32(pb); /* file size */ |
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tag = avio_rl32(pb); |
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if (tag != MKTAG('X', 'W', 'M', 'A')) |
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return -1; |
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/* parse fmt header */ |
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tag = avio_rl32(pb); |
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if (tag != MKTAG('f', 'm', 't', ' ')) |
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return -1; |
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size = avio_rl32(pb); |
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st = av_new_stream(s, 0); |
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if (!st) |
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return AVERROR(ENOMEM); |
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ff_get_wav_header(pb, st->codec, size); |
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st->need_parsing = AVSTREAM_PARSE_NONE; |
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/* All xWMA files I have seen contained WMAv2 data. If there are files
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* using WMA Pro or some other codec, then we need to figure out the right |
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* extradata for that. Thus, ask the user for feedback, but try to go on |
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* anyway. |
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*/ |
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if (st->codec->codec_id != CODEC_ID_WMAV2) { |
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av_log(s, AV_LOG_WARNING, "unexpected codec (tag 0x04%x; id %d)\n", |
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st->codec->codec_tag, st->codec->codec_id); |
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av_log_ask_for_sample(s, NULL); |
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} else { |
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/* In all xWMA files I have seen, there is no extradata. But the WMA
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* codecs require extradata, so we provide our own fake extradata. |
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* |
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* First, check that there really was no extradata in the header. If |
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* there was, then try to use, after asking the the user to provide a |
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* sample of this unusual file. |
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*/ |
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if (st->codec->extradata_size != 0) { |
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/* Surprise, surprise: We *did* get some extradata. No idea
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* if it will work, but just go on and try it, after asking |
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* the user for a sample. |
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*/ |
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av_log(s, AV_LOG_WARNING, "unexpected extradata (%d bytes)\n", |
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st->codec->extradata_size); |
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av_log_ask_for_sample(s, NULL); |
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} else { |
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st->codec->extradata_size = 6; |
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st->codec->extradata = av_mallocz(6 + FF_INPUT_BUFFER_PADDING_SIZE); |
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if (!st->codec->extradata) |
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return AVERROR(ENOMEM); |
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/* setup extradata with our experimentally obtained value */ |
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st->codec->extradata[4] = 31; |
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} |
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} |
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/* set the sample rate */ |
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av_set_pts_info(st, 64, 1, st->codec->sample_rate); |
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/* parse the remaining RIFF chunks */ |
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for (;;) { |
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if (pb->eof_reached) |
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return -1; |
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/* read next chunk tag */ |
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tag = avio_rl32(pb); |
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size = avio_rl32(pb); |
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if (tag == MKTAG('d', 'a', 't', 'a')) { |
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/* We assume that the data chunk comes last. */ |
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break; |
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} else if (tag == MKTAG('d','p','d','s')) { |
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/* Quoting the MSDN xWMA docs on the dpds chunk: "Contains the
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* decoded packet cumulative data size array, each element is the |
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* number of bytes accumulated after the corresponding xWMA packet |
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* is decoded in order" |
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* |
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* Each packet has size equal to st->codec->block_align, which in |
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* all cases I saw so far was always 2230. Thus, we can use the |
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* dpds data to compute a seeking index. |
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*/ |
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/* Error out if there is more than one dpds chunk. */ |
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if (dpds_table) { |
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av_log(s, AV_LOG_ERROR, "two dpds chunks present\n"); |
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return -1; |
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} |
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/* Compute the number of entries in the dpds chunk. */ |
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if (size & 3) { /* Size should be divisible by four */ |
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av_log(s, AV_LOG_WARNING, "dpds chunk size "PRId64" not divisible by 4\n", size); |
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} |
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dpds_table_size = size / 4; |
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if (dpds_table_size == 0 || dpds_table_size >= INT_MAX / 4) { |
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av_log(s, AV_LOG_ERROR, "dpds chunk size "PRId64" invalid\n", size); |
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return -1; |
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} |
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/* Allocate some temporary storage to keep the dpds data around.
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* for processing later on. |
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*/ |
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dpds_table = av_malloc(dpds_table_size * sizeof(uint32_t)); |
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if (!dpds_table) { |
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return AVERROR(ENOMEM); |
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} |
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for (i = 0; i < dpds_table_size; ++i) { |
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dpds_table[i] = avio_rl32(pb); |
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size -= 4; |
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} |
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} |
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avio_skip(pb, size); |
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} |
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/* Determine overall data length */ |
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if (size < 0) |
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return -1; |
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if (!size) { |
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xwma->data_end = INT64_MAX; |
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} else |
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xwma->data_end = avio_tell(pb) + size; |
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if (dpds_table && dpds_table_size) { |
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int64_t cur_pos; |
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const uint32_t bytes_per_sample |
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= (st->codec->channels * st->codec->bits_per_coded_sample) >> 3; |
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/* Estimate the duration from the total number of output bytes. */ |
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const uint64_t total_decoded_bytes = dpds_table[dpds_table_size - 1]; |
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st->duration = total_decoded_bytes / bytes_per_sample; |
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/* Use the dpds data to build a seek table. We can only do this after
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* we know the offset to the data chunk, as we need that to determine |
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* the actual offset to each input block. |
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* Note: If we allowed ourselves to assume that the data chunk always |
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* follows immediately after the dpds block, we could of course guess |
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* the data block's start offset already while reading the dpds chunk. |
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* I decided against that, just in case other chunks ever are |
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* discovered. |
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*/ |
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cur_pos = avio_tell(pb); |
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for (i = 0; i < dpds_table_size; ++i) { |
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/* From the number of output bytes that would accumulate in the
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* output buffer after decoding the first (i+1) packets, we compute |
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* an offset / timestamp pair. |
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*/ |
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av_add_index_entry(st, |
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cur_pos + (i+1) * st->codec->block_align, /* pos */ |
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dpds_table[i] / bytes_per_sample, /* timestamp */ |
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st->codec->block_align, /* size */ |
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0, /* duration */ |
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AVINDEX_KEYFRAME); |
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} |
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} else if (st->codec->bit_rate) { |
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/* No dpds chunk was present (or only an empty one), so estimate
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* the total duration using the average bits per sample and the |
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* total data length. |
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*/ |
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st->duration = (size<<3) * st->codec->sample_rate / st->codec->bit_rate; |
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} |
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av_free(dpds_table); |
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return 0; |
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} |
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static int xwma_read_packet(AVFormatContext *s, AVPacket *pkt) |
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{ |
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int ret, size; |
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int64_t left; |
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AVStream *st; |
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XWMAContext *xwma = s->priv_data; |
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st = s->streams[0]; |
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left = xwma->data_end - avio_tell(s->pb); |
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if (left <= 0) { |
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return AVERROR_EOF; |
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} |
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/* read a single block; the default block size is 2230. */ |
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size = (st->codec->block_align > 1) ? st->codec->block_align : 2230; |
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size = FFMIN(size, left); |
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ret = av_get_packet(s->pb, pkt, size); |
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if (ret < 0) |
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return ret; |
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pkt->stream_index = 0; |
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return ret; |
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} |
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AVInputFormat ff_xwma_demuxer = { |
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"xwma", |
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NULL_IF_CONFIG_SMALL("Microsoft xWMA"), |
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sizeof(XWMAContext), |
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xwma_probe, |
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xwma_read_header, |
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xwma_read_packet, |
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}; |
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