From e32a99264be6ce0d3ec060fdb8b56463b2f0b8cd Mon Sep 17 00:00:00 2001 From: Vesselin Bontchev Date: Sun, 19 Jul 2015 23:16:36 +0200 Subject: Add support for Audible AA files https://en.wikipedia.org/wiki/Audible.com#Quality --- libavformat/Makefile | 1 + libavformat/aadec.c | 303 +++++++++++++++++++++++++++++++++++++++++++++++ libavformat/allformats.c | 1 + 3 files changed, 305 insertions(+) create mode 100644 libavformat/aadec.c (limited to 'libavformat') diff --git a/libavformat/Makefile b/libavformat/Makefile index cc73fd8b02..466da516ad 100644 --- a/libavformat/Makefile +++ b/libavformat/Makefile @@ -59,6 +59,7 @@ OBJS-$(CONFIG_SHARED) += log2_tab.o golomb_tab.o # muxers/demuxers OBJS-$(CONFIG_A64_MUXER) += a64.o rawenc.o +OBJS-$(CONFIG_AA_DEMUXER) += aadec.o OBJS-$(CONFIG_AAC_DEMUXER) += aacdec.o apetag.o img2.o rawdec.o OBJS-$(CONFIG_AC3_DEMUXER) += ac3dec.o rawdec.o OBJS-$(CONFIG_AC3_MUXER) += rawenc.o diff --git a/libavformat/aadec.c b/libavformat/aadec.c new file mode 100644 index 0000000000..8e6140e189 --- /dev/null +++ b/libavformat/aadec.c @@ -0,0 +1,303 @@ +/* + * Audible AA demuxer + * Copyright (c) 2015 Vesselin Bontchev + * + * Header parsing is borrowed from https://github.com/jteeuwen/audible project. + * Copyright (c) 2001-2014, Jim Teeuwen + * + * Redistribution and use in source and binary forms, with or without modification, + * are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, this + * list of conditions and the following disclaimer. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR + * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON + * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "avformat.h" +#include "internal.h" +#include "libavutil/intreadwrite.h" +#include "libavutil/tea.h" +#include "libavutil/opt.h" + +#define AA_MAGIC 1469084982 /* this identifies an audible .aa file */ +#define MAX_CODEC_SECOND_SIZE 3982 +#define MAX_TOC_ENTRIES 16 +#define MAX_DICTIONARY_ENTRIES 128 +#define TEA_BLOCK_SIZE 8 + +typedef struct AADemuxContext { + AVClass *class; + uint8_t *aa_fixed_key; + int aa_fixed_key_len; + int codec_second_size; + int current_codec_second_size; + int chapter_idx; + struct AVTEA *tea_ctx; + uint8_t file_key[16]; + int64_t current_chapter_size; +} AADemuxContext; + +static int get_second_size(char *codec_name) +{ + int result = -1; + + if (!strcmp(codec_name, "mp332")) { + result = 3982; + } else if (!strcmp(codec_name, "acelp16")) { + result = 2000; + } else if (!strcmp(codec_name, "acelp85")) { + result = 1045; + } + + return result; +} + +static int aa_read_header(AVFormatContext *s) +{ + int i, j, idx, largest_idx = -1; + uint32_t nkey, nval, toc_size, npairs, header_seed, start; + char key[128], val[128], codec_name[64] = {0}; + uint8_t output[24], dst[8], src[8]; + int64_t largest_size = -1, current_size = -1; + struct toc_entry { + uint32_t offset; + uint32_t size; + } TOC[MAX_TOC_ENTRIES]; + uint32_t header_key_part[4]; + uint8_t header_key[16]; + AADemuxContext *c = s->priv_data; + AVIOContext *pb = s->pb; + AVStream *st; + + /* parse .aa header */ + avio_skip(pb, 4); // file size + avio_skip(pb, 4); // magic string + toc_size = avio_rb32(pb); // TOC size + avio_skip(pb, 4); // unidentified integer + if (toc_size > MAX_TOC_ENTRIES) + return AVERROR_INVALIDDATA; + for (i = 0; i < toc_size; i++) { // read TOC + avio_skip(pb, 4); // TOC entry index + TOC[i].offset = avio_rb32(pb); // block offset + TOC[i].size = avio_rb32(pb); // block size + } + avio_skip(pb, 24); // header termination block (ignored) + npairs = avio_rb32(pb); // read dictionary entries + if (npairs > MAX_DICTIONARY_ENTRIES) + return AVERROR_INVALIDDATA; + for (i = 0; i < npairs; i++) { + memset(val, 0, sizeof(val)); + memset(key, 0, sizeof(key)); + avio_skip(pb, 1); // unidentified integer + nkey = avio_rb32(pb); // key string length + nval = avio_rb32(pb); // value string length + if (nkey > sizeof(key)) { + avio_skip(pb, nkey); + } else { + avio_read(pb, key, nkey); // key string + } + if (nval > sizeof(val)) { + avio_skip(pb, nval); + } else { + avio_read(pb, val, nval); // value string + } + if (!strcmp(key, "codec")) { + strncpy(codec_name, val, sizeof(codec_name) - 1); + } + if (!strcmp(key, "HeaderSeed")) { + header_seed = atoi(val); + } + if (!strcmp(key, "HeaderKey")) { // this looks like "1234567890 1234567890 1234567890 1234567890" + sscanf(val, "%d%d%d%d", &header_key_part[0], &header_key_part[1], &header_key_part[2], &header_key_part[3]); + for (idx = 0; idx < 4; idx++) { + AV_WB32(&header_key[idx * 4], header_key_part[idx]); // convert each part to BE! + } + } + } + + /* verify fixed key */ + if (c->aa_fixed_key_len != 16) { + av_log(s, AV_LOG_ERROR, "aa_fixed_key value needs to be 16 bytes!\n"); + return AVERROR(EINVAL); + } + + /* verify codec */ + if ((c->codec_second_size = get_second_size(codec_name)) == -1) { + av_log(s, AV_LOG_ERROR, "unknown codec <%s>!\n", codec_name); + return AVERROR(EINVAL); + } + + /* decryption key derivation */ + c->tea_ctx = av_tea_alloc(); + if (!c->tea_ctx) + return AVERROR(ENOMEM); + av_tea_init(c->tea_ctx, c->aa_fixed_key, 16); + output[0] = output[1] = 0; // purely for padding purposes + memcpy(output + 2, &header_key, 16); + idx = 0; + for (i = 0; i < 3; i++) { // TEA CBC with weird mixed endianness + AV_WB32(src, header_seed); + AV_WB32(src + 4, header_seed + 1); + header_seed += 2; + av_tea_crypt(c->tea_ctx, dst, src, 1, NULL, 0); // TEA ECB encrypt + for (j = 0; j < TEA_BLOCK_SIZE && idx < 18; j+=1, idx+=1) { + output[idx] = output[idx] ^ dst[j]; + } + } + memcpy(c->file_key, output + 2, 16); // skip first 2 bytes of output + + /* decoder setup */ + st = avformat_new_stream(s, NULL); + if (!st) { + av_freep(&c->tea_ctx); + return AVERROR(ENOMEM); + } + st->codec->codec_type = AVMEDIA_TYPE_AUDIO; + if (!strcmp(codec_name, "mp332")) { + st->codec->codec_id = AV_CODEC_ID_MP3; + st->codec->sample_rate = 22050; + st->need_parsing = AVSTREAM_PARSE_FULL_RAW; + st->start_time = 0; + } else if (!strcmp(codec_name, "acelp85")) { + st->codec->codec_id = AV_CODEC_ID_SIPR; + st->codec->block_align = 19; + st->codec->channels = 1; + st->codec->sample_rate = 8500; + } else if (!strcmp(codec_name, "acelp16")) { + st->codec->codec_id = AV_CODEC_ID_SIPR; + st->codec->block_align = 20; + st->codec->channels = 1; + st->codec->sample_rate = 16000; + } + + /* determine, and jump to audio start offset */ + for (i = 1; i < toc_size; i++) { // skip the first entry! + current_size = TOC[i].size; + if (current_size > largest_size) { + largest_idx = i; + largest_size = current_size; + } + } + start = TOC[largest_idx].offset; + avio_seek(pb, start, SEEK_SET); + c->current_chapter_size = 0; + + return 0; +} + +static int aa_read_packet(AVFormatContext *s, AVPacket *pkt) +{ + uint8_t dst[TEA_BLOCK_SIZE]; + uint8_t src[TEA_BLOCK_SIZE]; + int i; + int trailing_bytes; + int blocks; + uint8_t buf[MAX_CODEC_SECOND_SIZE * 2]; + int written = 0; + int ret; + AADemuxContext *c = s->priv_data; + + // are we at the start of a chapter? + if (c->current_chapter_size == 0) { + c->current_chapter_size = avio_rb32(s->pb); + if (c->current_chapter_size == 0) { + return AVERROR_EOF; + } + av_log(s, AV_LOG_DEBUG, "Chapter %d (%" PRId64 " bytes)\n", c->chapter_idx, c->current_chapter_size); + c->chapter_idx = c->chapter_idx + 1; + avio_skip(s->pb, 4); // data start offset + c->current_codec_second_size = c->codec_second_size; + } + + // is this the last block in this chapter? + if (c->current_chapter_size / c->current_codec_second_size == 0) { + c->current_codec_second_size = c->current_chapter_size % c->current_codec_second_size; + } + + // decrypt c->current_codec_second_size bytes + blocks = c->current_codec_second_size / TEA_BLOCK_SIZE; + for (i = 0; i < blocks; i++) { + avio_read(s->pb, src, TEA_BLOCK_SIZE); + av_tea_init(c->tea_ctx, c->file_key, 16); + av_tea_crypt(c->tea_ctx, dst, src, 1, NULL, 1); + memcpy(buf + written, dst, TEA_BLOCK_SIZE); + written = written + TEA_BLOCK_SIZE; + } + trailing_bytes = c->current_codec_second_size % TEA_BLOCK_SIZE; + if (trailing_bytes != 0) { // trailing bytes are left unencrypted! + avio_read(s->pb, src, trailing_bytes); + memcpy(buf + written, src, trailing_bytes); + written = written + trailing_bytes; + } + + // update state + c->current_chapter_size = c->current_chapter_size - c->current_codec_second_size; + if (c->current_chapter_size <= 0) + c->current_chapter_size = 0; + + ret = av_new_packet(pkt, written); + if (ret < 0) + return ret; + memcpy(pkt->data, buf, written); + + return 0; +} + +static int aa_probe(AVProbeData *p) +{ + uint8_t *buf = p->buf; + + // first 4 bytes are file size, next 4 bytes are the magic + if (AV_RB32(buf+4) != AA_MAGIC) + return 0; + + return AVPROBE_SCORE_MAX / 2; +} + +static int aa_read_close(AVFormatContext *s) +{ + AADemuxContext *c = s->priv_data; + + av_freep(&c->tea_ctx); + + return 0; +} + +#define OFFSET(x) offsetof(AADemuxContext, x) +static const AVOption aa_options[] = { + { "aa_fixed_key", // extracted from libAAX_SDK.so and AAXSDKWin.dll files! + "Fixed key used for handling Audible AA files", OFFSET(aa_fixed_key), + AV_OPT_TYPE_BINARY, {.str="77214d4b196a87cd520045fd2a51d673"}, + .flags = AV_OPT_FLAG_DECODING_PARAM }, + { NULL }, +}; + +static const AVClass aa_class = { + .class_name = "aa", + .item_name = av_default_item_name, + .option = aa_options, + .version = LIBAVUTIL_VERSION_INT, +}; + +AVInputFormat ff_aa_demuxer = { + .name = "aa", + .long_name = NULL_IF_CONFIG_SMALL("Audible AA format files"), + .priv_class = &aa_class, + .priv_data_size = sizeof(AADemuxContext), + .extensions = "aa", + .read_probe = aa_probe, + .read_header = aa_read_header, + .read_packet = aa_read_packet, + .read_close = aa_read_close, + .flags = AVFMT_GENERIC_INDEX, +}; diff --git a/libavformat/allformats.c b/libavformat/allformats.c index 181cb9e6e9..0a24ac718b 100644 --- a/libavformat/allformats.c +++ b/libavformat/allformats.c @@ -60,6 +60,7 @@ void av_register_all(void) /* (de)muxers */ REGISTER_MUXER (A64, a64); + REGISTER_DEMUXER (AA, aa); REGISTER_DEMUXER (AAC, aac); REGISTER_MUXDEMUX(AC3, ac3); REGISTER_DEMUXER (ACT, act); -- cgit v1.2.3