[FFmpeg-devel] [PATCH v4 1/1] avformat: add mca demuxer

liushuyu at aosc.io liushuyu at aosc.io
Fri Sep 4 01:32:37 EEST 2020


From: Zixing Liu <liushuyu at aosc.io>

Signed-off-by: liushuyu <liushuyu at aosc.io>
---
 Changelog                |   1 +
 doc/general.texi         |   2 +
 libavformat/Makefile     |   1 +
 libavformat/allformats.c |   1 +
 libavformat/mca.c        | 226 +++++++++++++++++++++++++++++++++++++++
 libavformat/version.h    |   2 +-
 6 files changed, 232 insertions(+), 1 deletion(-)
 create mode 100644 libavformat/mca.c

diff --git a/Changelog b/Changelog
index d8109c6..d5f1b04 100644
--- a/Changelog
+++ b/Changelog
@@ -20,6 +20,7 @@ version <next>:
 - MobiClip video decoder
 - MOFLEX demuxer
 - MODS demuxer
+- MCA demuxer
 
 
 version 4.3:
diff --git a/doc/general.texi b/doc/general.texi
index d618565..fa76ed4 100644
--- a/doc/general.texi
+++ b/doc/general.texi
@@ -524,6 +524,8 @@ library:
     @tab Metadata in text format.
 @item MAXIS XA                  @tab   @tab X
     @tab Used in Sim City 3000; file extension .xa.
+ at item MCA                       @tab   @tab X
+    @tab Used in some games from Capcom; file extension .mca.
 @item MD Studio                 @tab   @tab X
 @item Metal Gear Solid: The Twin Snakes @tab @tab X
 @item Megalux Frame             @tab   @tab X
diff --git a/libavformat/Makefile b/libavformat/Makefile
index 7f852c0..9d2e157 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -305,6 +305,7 @@ OBJS-$(CONFIG_MATROSKA_MUXER)            += matroskaenc.o matroska.o \
                                             av1.o avc.o hevc.o \
                                             flacenc_header.o avlanguage.o \
                                             vorbiscomment.o wv.o
+OBJS-$(CONFIG_MCA_DEMUXER)               += mca.o
 OBJS-$(CONFIG_MCC_DEMUXER)               += mccdec.o subtitles.o
 OBJS-$(CONFIG_MD5_MUXER)                 += hashenc.o
 OBJS-$(CONFIG_MGSTS_DEMUXER)             += mgsts.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 8a733b3..0e79eef 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -232,6 +232,7 @@ extern AVInputFormat  ff_lvf_demuxer;
 extern AVInputFormat  ff_lxf_demuxer;
 extern AVInputFormat  ff_m4v_demuxer;
 extern AVOutputFormat ff_m4v_muxer;
+extern AVInputFormat  ff_mca_demuxer;
 extern AVInputFormat  ff_mcc_demuxer;
 extern AVOutputFormat ff_md5_muxer;
 extern AVInputFormat  ff_matroska_demuxer;
diff --git a/libavformat/mca.c b/libavformat/mca.c
new file mode 100644
index 0000000..f3f3471
--- /dev/null
+++ b/libavformat/mca.c
@@ -0,0 +1,226 @@
+/*
+ * MCA demuxer
+ * Copyright (c) 2020 Zixing Liu
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/intreadwrite.h"
+#include "avformat.h"
+#include "avio_internal.h"
+#include "internal.h"
+
+typedef struct MCADemuxContext {
+    uint32_t block_count;
+    uint16_t block_size;
+    uint32_t current_block;
+    uint32_t data_start;
+    uint32_t samples_per_block;
+} MCADemuxContext;
+
+static int probe(const AVProbeData *p)
+{
+    if (AV_RL32(p->buf) == MKTAG('M', 'A', 'D', 'P') &&
+        AV_RL16(p->buf + 4) <= 0x5)
+        return AVPROBE_SCORE_MAX / 3 * 2;
+    return 0;
+}
+
+static int read_header(AVFormatContext *s)
+{
+    AVStream *st;
+    MCADemuxContext *m = s->priv_data;
+    AVCodecParameters *par;
+    int64_t file_size = avio_size(s->pb);
+    uint16_t version = 0;
+    uint32_t header_size, data_size, data_offset, loop_start, loop_end,
+        nb_samples, nb_metadata, coef_offset = 0;
+    int ch, ret;
+    int64_t ret_size;
+
+    st = avformat_new_stream(s, NULL);
+    if (!st)
+        return AVERROR(ENOMEM);
+    par = st->codecpar;
+    par->codec_type = AVMEDIA_TYPE_AUDIO;
+
+    // parse file headers
+    avio_skip(s->pb, 0x4);      // skip the file magic
+    version          = avio_rl16(s->pb);
+    avio_skip(s->pb, 0x2);      // padding
+    par->channels    = avio_r8(s->pb);
+    avio_skip(s->pb, 0x1);      // padding
+    m->block_size    = avio_rl16(s->pb);
+    nb_samples       = avio_rl32(s->pb);
+    par->sample_rate = avio_rl32(s->pb);
+    loop_start       = avio_rl32(s->pb);
+    loop_end         = avio_rl32(s->pb);
+    header_size      = avio_rl32(s->pb);
+    data_size        = avio_rl32(s->pb);
+    avio_skip(s->pb, 0x4);
+    nb_metadata      = avio_rl16(s->pb);
+    avio_skip(s->pb, 0x2);      // unknown u16 field
+
+    // samples per frame = 14; frame size = 8 (2^3)
+    m->samples_per_block = (m->block_size * 14) >> 3;
+
+    if (m->samples_per_block < 1)
+        return AVERROR_INVALIDDATA;
+
+    m->block_count = nb_samples / m->samples_per_block;
+    st->duration = nb_samples;
+
+    // sanity checks
+    if (!par->channels || par->sample_rate <= 0
+        || loop_start > loop_end || m->block_count < 1)
+        return AVERROR_INVALIDDATA;
+    if ((ret = av_dict_set_int(&s->metadata, "loop_start",
+                        av_rescale(loop_start, AV_TIME_BASE,
+                                   par->sample_rate), 0)) < 0)
+        return ret;
+    if ((ret = av_dict_set_int(&s->metadata, "loop_end",
+                        av_rescale(loop_end, AV_TIME_BASE,
+                                   par->sample_rate), 0)) < 0)
+        return ret;
+    if ((32 + 4 + m->block_size) > (INT_MAX / par->channels) ||
+        (32 + 4 + m->block_size) * par->channels > INT_MAX - 8)
+        return AVERROR_INVALIDDATA;
+    avpriv_set_pts_info(st, 64, 1, par->sample_rate);
+
+    if (version <= 4) {
+        // version <= 4 needs to use the file size to calculate the offsets
+        if (file_size < 0) {
+            return AVERROR(EIO);
+        }
+        if (file_size - data_size > UINT32_MAX)
+            return AVERROR_INVALIDDATA;
+        m->data_start = file_size - data_size;
+        if (version <= 3) {
+            nb_metadata = 0;
+            // header_size is not available or incorrect in older versions
+            header_size = m->data_start;
+        }
+    } else if (version == 5) {
+        // read data_start location from the header
+        if (0x30 * par->channels + 0x4 > header_size)
+            return AVERROR_INVALIDDATA;
+        data_offset = header_size - 0x30 * par->channels - 0x4;
+        if ((ret_size = avio_seek(s->pb, data_offset, SEEK_SET)) < 0)
+            return ret_size;
+        m->data_start = avio_rl32(s->pb);
+        // check if the metadata is reasonable
+        if (file_size > 0 && (int64_t)m->data_start + data_size > file_size) {
+            // the header is broken beyond repair
+            if ((int64_t)header_size + data_size > file_size) {
+                av_log(s, AV_LOG_ERROR,
+                       "MCA metadata corrupted, unable to determine the data offset.\n");
+                return AVERROR_INVALIDDATA;
+            }
+            // recover the data_start information from the data size
+            av_log(s, AV_LOG_WARNING,
+                   "Incorrect header size found in metadata, "
+                   "header size approximated from the data size\n");
+            if (file_size - data_offset > UINT32_MAX)
+                return AVERROR_INVALIDDATA;
+            m->data_start = file_size - data_size;
+        }
+    } else {
+        avpriv_request_sample(s, "version %d", version);
+        return AVERROR_PATCHWELCOME;
+    }
+
+    // coefficient alignment = 0x30; metadata size = 0x14
+    if (0x30 * par->channels + nb_metadata * 0x14 > header_size)
+        return AVERROR_INVALIDDATA;
+    coef_offset =
+        header_size - 0x30 * par->channels + nb_metadata * 0x14;
+
+    st->start_time = 0;
+    par->codec_id = AV_CODEC_ID_ADPCM_THP_LE;
+
+    ret = ff_alloc_extradata(st->codecpar, 32 * par->channels);
+    if (ret < 0)
+        return ret;
+
+    if ((ret_size = avio_seek(s->pb, coef_offset, SEEK_SET)) < 0)
+        return ret_size;
+    for (ch = 0; ch < par->channels; ch++) {
+        if ((ret = ffio_read_size(s->pb, par->extradata + ch * 32, 32)) < 0)
+            return ret;
+        // 0x30 (alignment) - 0x20 (actual size, 32) = 0x10 (padding)
+        avio_skip(s->pb, 0x10);
+    }
+
+    // seek to the beginning of the adpcm data
+    // there are some files where the adpcm audio data is not immediately after the header
+    if ((ret_size = avio_seek(s->pb, m->data_start, SEEK_SET)) < 0)
+        return ret_size;
+
+    return 0;
+}
+
+static int read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    AVCodecParameters *par = s->streams[0]->codecpar;
+    MCADemuxContext *m     = s->priv_data;
+    uint16_t size          = m->block_size;
+    uint32_t samples       = m->samples_per_block;
+    int ret = 0;
+
+    if (avio_feof(s->pb))
+        return AVERROR_EOF;
+    m->current_block++;
+    if (m->current_block > m->block_count)
+        return AVERROR_EOF;
+
+    if ((ret = av_get_packet(s->pb, pkt, size * par->channels)) < 0)
+        return ret;
+    pkt->duration = samples;
+    pkt->stream_index = 0;
+
+    return 0;
+}
+
+static int read_seek(AVFormatContext *s, int stream_index,
+                     int64_t timestamp, int flags)
+{
+    AVStream *st = s->streams[stream_index];
+    MCADemuxContext *m = s->priv_data;
+    int64_t ret = 0;
+
+    timestamp /= m->samples_per_block;
+    ret = avio_seek(s->pb, m->data_start + timestamp * m->block_size *
+                    st->codecpar->channels, SEEK_SET);
+
+    if (ret < 0)
+        return ret;
+
+    m->current_block = timestamp;
+    ff_update_cur_dts(s, st, timestamp * m->samples_per_block);
+    return 0;
+}
+
+AVInputFormat ff_mca_demuxer = {
+    .name           = "mca",
+    .long_name      = NULL_IF_CONFIG_SMALL("MCA Audio Format"),
+    .priv_data_size = sizeof(MCADemuxContext),
+    .read_probe     = probe,
+    .read_header    = read_header,
+    .read_packet    = read_packet,
+    .read_seek      = read_seek,
+    .extensions     = "mca",
+};
diff --git a/libavformat/version.h b/libavformat/version.h
index 4208d38..7771a6a 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -32,7 +32,7 @@
 // Major bumping may affect Ticket5467, 5421, 5451(compatibility with Chromium)
 // Also please add any ticket numbers that you believe might be affected here
 #define LIBAVFORMAT_VERSION_MAJOR  58
-#define LIBAVFORMAT_VERSION_MINOR  53
+#define LIBAVFORMAT_VERSION_MINOR  54
 #define LIBAVFORMAT_VERSION_MICRO 100
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
-- 
2.28.0


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