--- /dev/null
+/*
+ * Rayman 2 APM Demuxer
+ *
+ * Copyright (C) 2020 Zane van Iperen (zane@zanevaniperen.com)
+ *
+ * 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 "avformat.h"
+#include "internal.h"
+#include "riff.h"
+#include "libavutil/internal.h"
+#include "libavutil/intreadwrite.h"
+
+#define APM_FILE_HEADER_SIZE 20
+#define APM_VS12_CHUNK_SIZE 76
+#define APM_MAX_READ_SIZE 4096
+
+#define APM_TAG_VS12 MKTAG('v', 's', '1', '2')
+#define APM_TAG_DATA MKTAG('D', 'A', 'T', 'A')
+
+typedef struct APMState {
+ int32_t has_saved;
+ int32_t predictor_r;
+ int32_t step_index_r;
+ int32_t saved_r;
+ int32_t predictor_l;
+ int32_t step_index_l;
+ int32_t saved_l;
+} APMState;
+
+typedef struct APMVS12Chunk {
+ uint32_t magic;
+ uint32_t file_size;
+ uint32_t data_size;
+ uint32_t unk1;
+ uint32_t unk2;
+ APMState state;
+ uint32_t pad[7];
+} APMVS12Chunk;
+
+static void apm_parse_vs12(APMVS12Chunk *vs12, const uint8_t *buf)
+{
+ vs12->magic = AV_RL32(buf + 0);
+ vs12->file_size = AV_RL32(buf + 4);
+ vs12->data_size = AV_RL32(buf + 8);
+ vs12->unk1 = AV_RL32(buf + 12);
+ vs12->unk2 = AV_RL32(buf + 16);
+
+ vs12->state.has_saved = AV_RL32(buf + 20);
+ vs12->state.predictor_r = AV_RL32(buf + 24);
+ vs12->state.step_index_r = AV_RL32(buf + 28);
+ vs12->state.saved_r = AV_RL32(buf + 32);
+ vs12->state.predictor_l = AV_RL32(buf + 36);
+ vs12->state.step_index_l = AV_RL32(buf + 40);
+ vs12->state.saved_l = AV_RL32(buf + 44);
+
+ for (int i = 0; i < FF_ARRAY_ELEMS(vs12->pad); i++)
+ vs12->pad[i] = AV_RL32(buf + 48 + (i * 4));
+}
+
+static int apm_probe(const AVProbeData *p)
+{
+ if (p->buf_size < 100)
+ return 0;
+
+ if (AV_RL32(p->buf + 20) != APM_TAG_VS12)
+ return 0;
+
+ if (AV_RL32(p->buf + 96) != APM_TAG_DATA)
+ return 0;
+
+ return AVPROBE_SCORE_MAX - 1;
+}
+
+static int apm_read_header(AVFormatContext *s)
+{
+ int64_t ret;
+ AVStream *st;
+ APMVS12Chunk vs12;
+ uint8_t buf[APM_VS12_CHUNK_SIZE];
+
+ if (!(st = avformat_new_stream(s, NULL)))
+ return AVERROR(ENOMEM);
+
+ /* The header starts with a WAVEFORMATEX */
+ if ((ret = ff_get_wav_header(s, s->pb, st->codecpar, APM_FILE_HEADER_SIZE, 0)) < 0)
+ return ret;
+
+ if (st->codecpar->bits_per_coded_sample != 4)
+ return AVERROR_INVALIDDATA;
+
+ if (st->codecpar->codec_tag != 0x2000)
+ return AVERROR_INVALIDDATA;
+
+ /* ff_get_wav_header() does most of the work, but we need to fix a few things. */
+ st->codecpar->codec_id = AV_CODEC_ID_ADPCM_IMA_APM;
+ st->codecpar->codec_tag = 0;
+
+ if (st->codecpar->channels == 2)
+ st->codecpar->channel_layout = AV_CH_LAYOUT_STEREO;
+ else if (st->codecpar->channels == 1)
+ st->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
+ else
+ return AVERROR_INVALIDDATA;
+
+ st->codecpar->format = AV_SAMPLE_FMT_S16;
+ st->codecpar->bits_per_raw_sample = 16;
+ st->codecpar->bit_rate = st->codecpar->channels *
+ st->codecpar->sample_rate *
+ st->codecpar->bits_per_coded_sample;
+
+ if ((ret = avio_read(s->pb, buf, APM_VS12_CHUNK_SIZE)) < 0)
+ return ret;
+ else if (ret != APM_VS12_CHUNK_SIZE)
+ return AVERROR(EIO);
+
+ apm_parse_vs12(&vs12, buf);
+
+ if (vs12.magic != APM_TAG_VS12) {
+ return AVERROR_INVALIDDATA;
+ }
+
+ if (vs12.state.has_saved) {
+ avpriv_request_sample(s, "Saved Samples");
+ return AVERROR_PATCHWELCOME;
+ }
+
+ if (avio_rl32(s->pb) != APM_TAG_DATA)
+ return AVERROR_INVALIDDATA;
+
+ if ((ret = ff_alloc_extradata(st->codecpar, 16)) < 0)
+ return ret;
+
+ AV_WL32(st->codecpar->extradata + 0, vs12.state.predictor_l);
+ AV_WL32(st->codecpar->extradata + 4, vs12.state.step_index_l);
+ AV_WL32(st->codecpar->extradata + 8, vs12.state.predictor_r);
+ AV_WL32(st->codecpar->extradata + 12, vs12.state.step_index_r);
+
+ avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
+ st->start_time = 0;
+ st->duration = vs12.data_size *
+ (8 / st->codecpar->bits_per_coded_sample) /
+ st->codecpar->channels;
+ return 0;
+}
+
+static int apm_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+ int ret;
+ AVCodecParameters *par = s->streams[0]->codecpar;
+
+ /*
+ * For future reference: if files with the `has_saved` field set ever
+ * surface, `saved_l`, and `saved_r` will each contain 8 "saved" samples
+ * that should be sent to the decoder before the actual data.
+ */
+
+ if ((ret = av_get_packet(s->pb, pkt, APM_MAX_READ_SIZE)) < 0)
+ return ret;
+
+ pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
+ pkt->stream_index = 0;
+ pkt->duration = ret * (8 / par->bits_per_coded_sample) / par->channels;
+
+ return 0;
+}
+
+AVInputFormat ff_apm_demuxer = {
+ .name = "apm",
+ .long_name = NULL_IF_CONFIG_SMALL("Ubisoft Rayman 2 APM"),
+ .read_probe = apm_probe,
+ .read_header = apm_read_header,
+ .read_packet = apm_read_packet
+};
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