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35ec5c819b
And move those stuff already in demuxer-only files to it. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
388 lines
14 KiB
C
388 lines
14 KiB
C
/*
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* Audible AA demuxer
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* Copyright (c) 2015 Vesselin Bontchev
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*
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* Header parsing is borrowed from https://github.com/jteeuwen/audible project.
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* Copyright (c) 2001-2014, Jim Teeuwen
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "avformat.h"
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#include "demux.h"
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#include "internal.h"
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#include "libavutil/avstring.h"
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#include "libavutil/dict.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/tea.h"
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#include "libavutil/opt.h"
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#define AA_MAGIC 1469084982 /* this identifies an audible .aa file */
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#define MAX_TOC_ENTRIES 16
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#define MAX_DICTIONARY_ENTRIES 128
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#define TEA_BLOCK_SIZE 8
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#define CHAPTER_HEADER_SIZE 8
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#define TIMEPREC 1000
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#define MP3_FRAME_SIZE 104
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typedef struct AADemuxContext {
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AVClass *class;
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uint8_t *aa_fixed_key;
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int aa_fixed_key_len;
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int codec_second_size;
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int current_codec_second_size;
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int chapter_idx;
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struct AVTEA *tea_ctx;
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uint8_t file_key[16];
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int64_t current_chapter_size;
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int64_t content_start;
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int64_t content_end;
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int seek_offset;
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} AADemuxContext;
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static int get_second_size(char *codec_name)
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{
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int result = -1;
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if (!strcmp(codec_name, "mp332")) {
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result = 3982;
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} else if (!strcmp(codec_name, "acelp16")) {
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result = 2000;
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} else if (!strcmp(codec_name, "acelp85")) {
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result = 1045;
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}
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return result;
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}
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static int aa_read_header(AVFormatContext *s)
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{
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int largest_idx = -1;
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uint32_t toc_size, npairs, header_seed = 0, start;
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char codec_name[64] = {0};
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uint8_t buf[24];
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int64_t largest_size = -1, current_size = -1, chapter_pos;
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struct toc_entry {
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uint32_t offset;
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uint32_t size;
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} TOC[MAX_TOC_ENTRIES];
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uint8_t header_key[16] = {0};
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AADemuxContext *c = s->priv_data;
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char file_key[2 * sizeof(c->file_key) + 1];
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AVIOContext *pb = s->pb;
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AVStream *st;
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FFStream *sti;
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int ret;
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/* parse .aa header */
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avio_skip(pb, 4); // file size
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avio_skip(pb, 4); // magic string
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toc_size = avio_rb32(pb); // TOC size
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avio_skip(pb, 4); // unidentified integer
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if (toc_size > MAX_TOC_ENTRIES || toc_size < 2)
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return AVERROR_INVALIDDATA;
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for (uint32_t i = 0; i < toc_size; i++) { // read TOC
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avio_skip(pb, 4); // TOC entry index
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TOC[i].offset = avio_rb32(pb); // block offset
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TOC[i].size = avio_rb32(pb); // block size
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}
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avio_skip(pb, 24); // header termination block (ignored)
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npairs = avio_rb32(pb); // read dictionary entries
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if (npairs > MAX_DICTIONARY_ENTRIES)
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return AVERROR_INVALIDDATA;
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for (uint32_t i = 0; i < npairs; i++) {
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char key[128], val[128];
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uint32_t nkey, nval;
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avio_skip(pb, 1); // unidentified integer
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nkey = avio_rb32(pb); // key string length
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nval = avio_rb32(pb); // value string length
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avio_get_str(pb, nkey, key, sizeof(key));
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avio_get_str(pb, nval, val, sizeof(val));
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if (!strcmp(key, "codec")) {
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av_log(s, AV_LOG_DEBUG, "Codec is <%s>\n", val);
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av_strlcpy(codec_name, val, sizeof(codec_name));
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} else if (!strcmp(key, "HeaderSeed")) {
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av_log(s, AV_LOG_DEBUG, "HeaderSeed is <%s>\n", val);
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header_seed = atoi(val);
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} else if (!strcmp(key, "HeaderKey")) { // this looks like "1234567890 1234567890 1234567890 1234567890"
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uint32_t header_key_part[4];
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av_log(s, AV_LOG_DEBUG, "HeaderKey is <%s>\n", val);
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ret = sscanf(val, "%"SCNu32"%"SCNu32"%"SCNu32"%"SCNu32,
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&header_key_part[0], &header_key_part[1], &header_key_part[2], &header_key_part[3]);
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if (ret != 4)
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return AVERROR_INVALIDDATA;
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for (int idx = 0; idx < 4; idx++)
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AV_WB32(&header_key[idx * 4], header_key_part[idx]); // convert each part to BE!
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ff_data_to_hex(key, header_key, sizeof(header_key), 1);
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av_log(s, AV_LOG_DEBUG, "Processed HeaderKey is %s\n", key);
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} else {
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av_dict_set(&s->metadata, key, val, 0);
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}
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}
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/* verify fixed key */
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if (c->aa_fixed_key_len != 16) {
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av_log(s, AV_LOG_ERROR, "aa_fixed_key value needs to be 16 bytes!\n");
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return AVERROR(EINVAL);
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}
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/* verify codec */
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if ((c->codec_second_size = get_second_size(codec_name)) == -1) {
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av_log(s, AV_LOG_ERROR, "unknown codec <%s>!\n", codec_name);
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return AVERROR(EINVAL);
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}
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/* decryption key derivation */
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c->tea_ctx = av_tea_alloc();
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if (!c->tea_ctx)
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return AVERROR(ENOMEM);
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av_tea_init(c->tea_ctx, c->aa_fixed_key, 16);
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for (int i = 0; i < 6; i++)
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AV_WB32(buf + 4 * i, header_seed + i);
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av_tea_crypt(c->tea_ctx, buf, buf, 3, NULL, 0);
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AV_WN64(c->file_key, AV_RN64(buf + 2) ^ AV_RN64(header_key));
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AV_WN64(c->file_key + 8, AV_RN64(buf + 10) ^ AV_RN64(header_key + 8));
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ff_data_to_hex(file_key, c->file_key, sizeof(c->file_key), 1);
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av_log(s, AV_LOG_DEBUG, "File key is %s\n", file_key);
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av_tea_init(c->tea_ctx, c->file_key, 16);
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/* decoder setup */
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st = avformat_new_stream(s, NULL);
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if (!st)
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return AVERROR(ENOMEM);
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sti = ffstream(st);
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st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
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if (!strcmp(codec_name, "mp332")) {
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st->codecpar->codec_id = AV_CODEC_ID_MP3;
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st->codecpar->sample_rate = 22050;
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sti->need_parsing = AVSTREAM_PARSE_FULL_RAW;
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avpriv_set_pts_info(st, 64, 8, 32000 * TIMEPREC);
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// encoded audio frame is MP3_FRAME_SIZE bytes (+1 with padding, unlikely)
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} else if (!strcmp(codec_name, "acelp85")) {
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st->codecpar->codec_id = AV_CODEC_ID_SIPR;
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st->codecpar->block_align = 19;
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st->codecpar->ch_layout.nb_channels = 1;
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st->codecpar->sample_rate = 8500;
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st->codecpar->bit_rate = 8500;
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sti->need_parsing = AVSTREAM_PARSE_FULL_RAW;
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avpriv_set_pts_info(st, 64, 8, 8500 * TIMEPREC);
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} else if (!strcmp(codec_name, "acelp16")) {
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st->codecpar->codec_id = AV_CODEC_ID_SIPR;
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st->codecpar->block_align = 20;
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st->codecpar->ch_layout.nb_channels = 1;
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st->codecpar->sample_rate = 16000;
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st->codecpar->bit_rate = 16000;
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sti->need_parsing = AVSTREAM_PARSE_FULL_RAW;
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avpriv_set_pts_info(st, 64, 8, 16000 * TIMEPREC);
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}
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/* determine, and jump to audio start offset */
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for (uint32_t i = 1; i < toc_size; i++) { // skip the first entry!
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current_size = TOC[i].size;
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if (current_size > largest_size) {
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largest_idx = i;
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largest_size = current_size;
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}
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}
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start = TOC[largest_idx].offset;
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avio_seek(pb, start, SEEK_SET);
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// extract chapter positions. since all formats have constant bit rate, use it
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// as time base in bytes/s, for easy stream position <-> timestamp conversion
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st->start_time = 0;
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c->content_start = start;
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c->content_end = start + largest_size;
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while ((chapter_pos = avio_tell(pb)) >= 0 && chapter_pos < c->content_end) {
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unsigned chapter_idx = s->nb_chapters;
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uint32_t chapter_size = avio_rb32(pb);
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if (chapter_size == 0 || avio_feof(pb))
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break;
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chapter_pos -= start + CHAPTER_HEADER_SIZE * chapter_idx;
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avio_skip(pb, 4 + chapter_size);
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if (!avpriv_new_chapter(s, chapter_idx, st->time_base,
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chapter_pos * TIMEPREC,
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(chapter_pos + chapter_size) * TIMEPREC, NULL))
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return AVERROR(ENOMEM);
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}
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st->duration = (largest_size - CHAPTER_HEADER_SIZE * s->nb_chapters) * TIMEPREC;
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avpriv_update_cur_dts(s, st, 0);
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avio_seek(pb, start, SEEK_SET);
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c->current_chapter_size = 0;
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c->seek_offset = 0;
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return 0;
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}
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static int aa_read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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int ret;
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AADemuxContext *c = s->priv_data;
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uint64_t pos = avio_tell(s->pb);
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// are we at the end of the audio content?
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if (pos >= c->content_end) {
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return AVERROR_EOF;
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}
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// are we at the start of a chapter?
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if (c->current_chapter_size == 0) {
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c->current_chapter_size = avio_rb32(s->pb);
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if (c->current_chapter_size == 0) {
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return AVERROR_EOF;
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}
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av_log(s, AV_LOG_DEBUG, "Chapter %d (%" PRId64 " bytes)\n", c->chapter_idx, c->current_chapter_size);
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c->chapter_idx = c->chapter_idx + 1;
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avio_skip(s->pb, 4); // data start offset
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c->current_codec_second_size = c->codec_second_size;
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}
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// is this the last block in this chapter?
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if (c->current_chapter_size / c->current_codec_second_size == 0) {
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c->current_codec_second_size = c->current_chapter_size % c->current_codec_second_size;
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}
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ret = av_get_packet(s->pb, pkt, c->current_codec_second_size);
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if (ret != c->current_codec_second_size)
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return AVERROR_EOF;
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// decrypt c->current_codec_second_size bytes in blocks of TEA_BLOCK_SIZE
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// trailing bytes are left unencrypted!
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av_tea_crypt(c->tea_ctx, pkt->data, pkt->data,
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c->current_codec_second_size / TEA_BLOCK_SIZE, NULL, 1);
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// update state
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c->current_chapter_size = c->current_chapter_size - c->current_codec_second_size;
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if (c->current_chapter_size <= 0)
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c->current_chapter_size = 0;
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if (c->seek_offset > c->current_codec_second_size)
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c->seek_offset = 0; // ignore wrong estimate
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pkt->data += c->seek_offset;
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pkt->size -= c->seek_offset;
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c->seek_offset = 0;
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return 0;
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}
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static int aa_read_seek(AVFormatContext *s,
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int stream_index, int64_t timestamp, int flags)
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{
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AADemuxContext *c = s->priv_data;
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AVChapter *ch;
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int64_t chapter_pos, chapter_start, chapter_size;
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int chapter_idx = 0;
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// find chapter containing seek timestamp
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if (timestamp < 0)
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timestamp = 0;
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while (chapter_idx < s->nb_chapters && timestamp >= s->chapters[chapter_idx]->end) {
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++chapter_idx;
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}
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if (chapter_idx >= s->nb_chapters) {
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chapter_idx = s->nb_chapters - 1;
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if (chapter_idx < 0) return -1; // there is no chapter.
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timestamp = s->chapters[chapter_idx]->end;
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}
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ch = s->chapters[chapter_idx];
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// sync by clamping timestamp to nearest valid block position in its chapter
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chapter_size = ch->end / TIMEPREC - ch->start / TIMEPREC;
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chapter_pos = av_rescale_rnd((timestamp - ch->start) / TIMEPREC,
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1, c->codec_second_size,
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(flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP)
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* c->codec_second_size;
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if (chapter_pos >= chapter_size)
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chapter_pos = chapter_size;
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chapter_start = c->content_start + (ch->start / TIMEPREC) + CHAPTER_HEADER_SIZE * (1 + chapter_idx);
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// reinit read state
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avio_seek(s->pb, chapter_start + chapter_pos, SEEK_SET);
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c->current_codec_second_size = c->codec_second_size;
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c->current_chapter_size = chapter_size - chapter_pos;
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c->chapter_idx = 1 + chapter_idx;
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// for unaligned frames, estimate offset of first frame in block (assume no padding)
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if (s->streams[0]->codecpar->codec_id == AV_CODEC_ID_MP3) {
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c->seek_offset = (MP3_FRAME_SIZE - chapter_pos % MP3_FRAME_SIZE) % MP3_FRAME_SIZE;
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}
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avpriv_update_cur_dts(s, s->streams[0], ch->start + (chapter_pos + c->seek_offset) * TIMEPREC);
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return 1;
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}
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static int aa_probe(const AVProbeData *p)
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{
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uint8_t *buf = p->buf;
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// first 4 bytes are file size, next 4 bytes are the magic
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if (AV_RB32(buf+4) != AA_MAGIC)
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return 0;
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return AVPROBE_SCORE_MAX / 2;
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}
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static int aa_read_close(AVFormatContext *s)
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{
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AADemuxContext *c = s->priv_data;
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av_freep(&c->tea_ctx);
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return 0;
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}
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#define OFFSET(x) offsetof(AADemuxContext, x)
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static const AVOption aa_options[] = {
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{ "aa_fixed_key", // extracted from libAAX_SDK.so and AAXSDKWin.dll files!
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"Fixed key used for handling Audible AA files", OFFSET(aa_fixed_key),
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AV_OPT_TYPE_BINARY, {.str="77214d4b196a87cd520045fd2a51d673"},
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.flags = AV_OPT_FLAG_DECODING_PARAM },
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{ NULL },
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};
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static const AVClass aa_class = {
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.class_name = "aa",
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.item_name = av_default_item_name,
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.option = aa_options,
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.version = LIBAVUTIL_VERSION_INT,
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};
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const AVInputFormat ff_aa_demuxer = {
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.name = "aa",
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.long_name = NULL_IF_CONFIG_SMALL("Audible AA format files"),
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.priv_class = &aa_class,
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.priv_data_size = sizeof(AADemuxContext),
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.extensions = "aa",
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.read_probe = aa_probe,
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.read_header = aa_read_header,
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.read_packet = aa_read_packet,
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.read_seek = aa_read_seek,
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.read_close = aa_read_close,
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.flags = AVFMT_NO_BYTE_SEEK | AVFMT_NOGENSEARCH,
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.flags_internal = FF_FMT_INIT_CLEANUP,
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};
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