[FFmpeg-cvslog] Add support for Audible AA files
Vesselin Bontchev
git at videolan.org
Fri Aug 21 06:53:25 CEST 2015
ffmpeg | branch: master | Vesselin Bontchev <vesselin.bontchev at yandex.com> | Sun Jul 19 23:16:36 2015 +0200| [e32a99264be6ce0d3ec060fdb8b56463b2f0b8cd] | committer: Vesselin Bontchev
Add support for Audible AA files
https://en.wikipedia.org/wiki/Audible.com#Quality
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=e32a99264be6ce0d3ec060fdb8b56463b2f0b8cd
---
MAINTAINERS | 1 +
doc/demuxers.texi | 6 +
doc/general.texi | 2 +
libavformat/Makefile | 1 +
libavformat/aadec.c | 303 ++++++++++++++++++++++++++++++++++++++++++++++
libavformat/allformats.c | 1 +
6 files changed, 314 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index b2aaf3c..94405e3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -399,6 +399,7 @@ Generic parts:
Muxers/Demuxers:
4xm.c Mike Melanson
+ aadec.c Vesselin Bontchev (vesselin.bontchev at yandex dot com)
adtsenc.c Robert Swain
afc.c Paul B Mahol
aiffdec.c Baptiste Coudurier, Matthieu Bouron
diff --git a/doc/demuxers.texi b/doc/demuxers.texi
index eb7cd4b..34bfc9b 100644
--- a/doc/demuxers.texi
+++ b/doc/demuxers.texi
@@ -18,6 +18,12 @@ enabled demuxers.
The description of some of the currently available demuxers follows.
+ at section aa
+
+Audible Format 2, 3, and 4 demuxer.
+
+This demuxer is used to demux Audible Format 2, 3, and 4 (.aa) files.
+
@section applehttp
Apple HTTP Live Streaming demuxer.
diff --git a/doc/general.texi b/doc/general.texi
index a260e79..2b782e0 100644
--- a/doc/general.texi
+++ b/doc/general.texi
@@ -228,6 +228,8 @@ library:
@item 8088flex TMV @tab @tab X
@item AAX @tab @tab X
@tab Audible Enhanced Audio format, used in audiobooks.
+ at item AA @tab @tab X
+ @tab Audible Format 2, 3, and 4, used in audiobooks.
@item ACT Voice @tab @tab X
@tab contains G.729 audio
@item Adobe Filmstrip @tab X @tab X
diff --git a/libavformat/Makefile b/libavformat/Makefile
index cc73fd8..466da51 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 0000000..8e6140e
--- /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 181cb9e..0a24ac7 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);
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