diff --git a/Changelog b/Changelog
index f525dcaaae..261b6b261a 100644
--- a/Changelog
+++ b/Changelog
@@ -24,6 +24,7 @@ version <next>:
 - MCA demuxer
 - AV1 decoder (Hardware acceleration used only)
 - SVS demuxer
+- Argonaut Games BRP demuxer
 
 
 version 4.3:
diff --git a/MAINTAINERS b/MAINTAINERS
index 30c2ec59e6..ac1f7242fc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -397,6 +397,7 @@ Muxers/Demuxers:
   apm.c                                 Zane van Iperen
   apngdec.c                             Benoit Fouet
   argo_asf.c                            Zane van Iperen
+  argo_brp.c                            Zane van Iperen
   ass*                                  Aurelien Jacobs
   astdec.c                              Paul B Mahol
   astenc.c                              James Almer
diff --git a/libavformat/Makefile b/libavformat/Makefile
index 5ce1e6464d..bbaf4de7ad 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -104,6 +104,7 @@ OBJS-$(CONFIG_APTX_HD_MUXER)             += rawenc.o
 OBJS-$(CONFIG_AQTITLE_DEMUXER)           += aqtitledec.o subtitles.o
 OBJS-$(CONFIG_ARGO_ASF_DEMUXER)          += argo_asf.o
 OBJS-$(CONFIG_ARGO_ASF_MUXER)            += argo_asf.o
+OBJS-$(CONFIG_ARGO_BRP_DEMUXER)          += argo_brp.o argo_asf.o
 OBJS-$(CONFIG_ASF_DEMUXER)               += asfdec_f.o asf.o asfcrypt.o \
                                             avlanguage.o
 OBJS-$(CONFIG_ASF_O_DEMUXER)             += asfdec_o.o asf.o asfcrypt.o \
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 82838e3c53..7aa54ad15d 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -65,6 +65,7 @@ extern AVOutputFormat ff_aptx_hd_muxer;
 extern AVInputFormat  ff_aqtitle_demuxer;
 extern AVInputFormat  ff_argo_asf_demuxer;
 extern AVOutputFormat ff_argo_asf_muxer;
+extern AVInputFormat  ff_argo_brp_demuxer;
 extern AVInputFormat  ff_asf_demuxer;
 extern AVOutputFormat ff_asf_muxer;
 extern AVInputFormat  ff_asf_o_demuxer;
diff --git a/libavformat/argo_brp.c b/libavformat/argo_brp.c
new file mode 100644
index 0000000000..122f616ecc
--- /dev/null
+++ b/libavformat/argo_brp.c
@@ -0,0 +1,449 @@
+/*
+ * Argonaut Games BRP 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 "libavutil/intreadwrite.h"
+#include "libavutil/avassert.h"
+#include "libavutil/internal.h"
+#include "argo_asf.h"
+
+#define BRP_TAG                 MKTAG('B', 'R', 'P', 'P')
+#define BRP_FILE_HEADER_SIZE    12
+#define BRP_BLOCK_HEADER_SIZE   12
+#define BRP_STREAM_HEADER_SIZE  20
+#define BRP_MAX_STREAMS         32 /* Soft cap, but even this is overkill. */
+#define BVID_HEADER_SIZE        16
+#define BRP_MIN_BUFFER_SIZE     FFMAX(FFMAX3(BRP_FILE_HEADER_SIZE,    \
+                                             BRP_BLOCK_HEADER_SIZE,   \
+                                             BRP_STREAM_HEADER_SIZE), \
+                                      BVID_HEADER_SIZE)
+
+#define BRP_CODEC_ID_BVID       MKTAG('B', 'V', 'I', 'D')
+#define BRP_CODEC_ID_BASF       MKTAG('B', 'A', 'S', 'F')
+
+typedef struct ArgoBRPFileHeader {
+    uint32_t magic;
+    uint32_t num_streams;
+    uint32_t byte_rate;
+} ArgoBRPFileHeader;
+
+typedef struct ArgoBRPBlockHeader {
+    int32_t  stream_id;
+    uint32_t start_ms;
+    uint32_t size;
+} ArgoBRPBlockHeader;
+
+typedef struct ArgoBVIDHeader {
+    uint32_t num_frames;
+    uint32_t width;
+    uint32_t height;
+    uint32_t depth;
+} ArgoBVIDHeader;
+
+typedef struct ArgoBRPStreamHeader {
+    uint32_t codec_id;
+    uint32_t id;
+    uint32_t duration_ms;
+    uint32_t byte_rate;
+    uint32_t extradata_size;
+    union
+    {
+        /* If codec_id == BRP_CODEC_ID_BVID */
+        ArgoBVIDHeader    bvid;
+        /* If codec_id == BRP_CODEC_ID_BASF */
+        ArgoASFFileHeader basf;
+    } extradata;
+} ArgoBRPStreamHeader;
+
+typedef struct ArgoBRPDemuxContext {
+    ArgoBRPFileHeader   fhdr;
+    ArgoBRPStreamHeader *streams;
+    /* To know how much of a BASF to give. */
+    int64_t             lastpts;
+    int                 hit_eof;
+
+    /* BASF-specific fields. */
+    struct {
+        int                 index;
+        ArgoASFChunkHeader  ckhdr;
+        int64_t             blocks_read;
+        int64_t             offset;
+        /* ms, not samples. */
+        int64_t             lastpts;
+    } basf;
+} ArgoBRPDemuxContext;
+
+static int argo_brp_probe(const AVProbeData *p)
+{
+    if (AV_RL32(p->buf) != BRP_TAG)
+        return 0;
+
+    return AVPROBE_SCORE_EXTENSION + 1;
+}
+
+static int argo_brp_read_close(AVFormatContext *s)
+{
+    ArgoBRPDemuxContext *brp = s->priv_data;
+
+    if (brp->streams != NULL)
+        av_freep(&brp->streams);
+
+    return 0;
+}
+
+static int read_extradata(AVFormatContext *s, const ArgoBRPStreamHeader *hdr,
+                          void *buf, size_t bufsz)
+{
+    const char *name;
+    uint32_t size;
+    int64_t ret;
+
+    if (hdr->codec_id == BRP_CODEC_ID_BVID) {
+        name = "BVID";
+        size = BVID_HEADER_SIZE;
+    } else if (hdr->codec_id == BRP_CODEC_ID_BASF) {
+        name = "BASF";
+        size = ASF_FILE_HEADER_SIZE;
+    } else {
+        avpriv_request_sample(s, "BRP codec id 0x%x", hdr->codec_id);
+
+        if ((ret = avio_skip(s->pb, hdr->extradata_size)) < 0)
+            return ret;
+
+        return 1;
+    }
+
+    if (hdr->extradata_size != size) {
+        av_log(s, AV_LOG_ERROR, "Invalid %s extradata size %u, expected %u\n",
+               name, hdr->extradata_size, size);
+        return AVERROR_INVALIDDATA;
+    }
+
+    av_assert0(bufsz >= size);
+
+    if ((ret = avio_read(s->pb, buf, size)) < 0)
+        return ret;
+
+    if (ret != size)
+        return AVERROR(EIO);
+
+    return 0;
+}
+
+static int argo_brp_read_header(AVFormatContext *s)
+{
+    int64_t ret;
+    AVIOContext *pb = s->pb;
+    ArgoBRPDemuxContext *brp = s->priv_data;
+    uint8_t buf[FFMAX(BRP_MIN_BUFFER_SIZE, ASF_MIN_BUFFER_SIZE)];
+
+    if ((ret = avio_read(pb, buf, BRP_FILE_HEADER_SIZE)) < 0)
+        return ret;
+    else if (ret != BRP_FILE_HEADER_SIZE)
+        return AVERROR(EIO);
+
+    brp->fhdr.magic       = AV_RL32(buf + 0);
+    brp->fhdr.num_streams = AV_RL32(buf + 4);
+    brp->fhdr.byte_rate   = AV_RL32(buf + 8);
+
+    if (brp->fhdr.magic != BRP_TAG)
+        return AVERROR_INVALIDDATA;
+
+    if (brp->fhdr.num_streams > BRP_MAX_STREAMS) {
+        avpriv_request_sample(s, ">%d streams", BRP_MAX_STREAMS);
+        return AVERROR_PATCHWELCOME;
+    }
+
+    if ((brp->streams = av_mallocz_array(brp->fhdr.num_streams, sizeof(ArgoBRPStreamHeader))) == NULL)
+        return AVERROR(ENOMEM);
+
+    /* Build the stream info. */
+    brp->basf.index = -1;
+    for (uint32_t i = 0; i < brp->fhdr.num_streams; i++) {
+        ArgoBRPStreamHeader *hdr = brp->streams + i;
+        AVStream *st;
+
+        if (!(st = avformat_new_stream(s, NULL))) {
+            ret = AVERROR(ENOMEM);
+            goto fail;
+        }
+
+        if ((ret = avio_read(pb, buf, BRP_STREAM_HEADER_SIZE)) < 0) {
+            goto fail;
+        } else if (ret != BRP_STREAM_HEADER_SIZE) {
+            ret = AVERROR(EIO);
+            goto fail;
+        }
+
+        hdr->codec_id       = AV_RL32(buf + 0);
+        hdr->id             = AV_RL32(buf + 4);
+        hdr->duration_ms    = AV_RL32(buf + 8);
+        hdr->byte_rate      = AV_RL32(buf + 12);
+        hdr->extradata_size = AV_RL32(buf + 16);
+
+        /* Timestamps are in milliseconds. */
+        avpriv_set_pts_info(st, 64, 1, 1000);
+        st->duration           = hdr->duration_ms;
+        st->codecpar->bit_rate = hdr->byte_rate * 8;
+
+        if ((ret = read_extradata(s, hdr, buf, sizeof(buf))) < 0) {
+            goto fail;
+        } else if (ret > 0) {
+            st->codecpar->codec_type = AVMEDIA_TYPE_UNKNOWN;
+            continue;
+        }
+
+        if (hdr->codec_id == BRP_CODEC_ID_BVID) {
+            ArgoBVIDHeader *bvid = &hdr->extradata.bvid;
+
+            st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
+
+            /* No decoder for this yet. */
+            st->codecpar->codec_id   = AV_CODEC_ID_NONE;
+
+            bvid->num_frames = AV_RL32(buf +  0);
+            bvid->width      = AV_RL32(buf +  4);
+            bvid->height     = AV_RL32(buf +  8);
+            bvid->depth      = AV_RL32(buf + 12);
+
+            /* These are from 1990's games, sanity check this. */
+            if (bvid->width >= 65536 || bvid->height >= 65536 ||
+                bvid->depth > 24     || bvid->depth % 8 != 0) {
+                ret = AVERROR_INVALIDDATA;
+                goto fail;
+            }
+
+            st->codecpar->width  = bvid->width;
+            st->codecpar->height = bvid->height;
+
+            if (bvid->depth == 8) {
+                st->codecpar->format = AV_PIX_FMT_PAL8;
+            } else if (bvid->depth == 24) {
+                st->codecpar->format = AV_PIX_FMT_RGB24;
+            } else {
+                avpriv_request_sample(s, "depth == %u", bvid->depth);
+                ret = AVERROR_PATCHWELCOME;
+                goto fail;
+            }
+        } else if (hdr->codec_id == BRP_CODEC_ID_BASF) {
+            /*
+             * It would make the demuxer significantly more complicated
+             * to support multiple BASF streams. I've never seen a file
+             * with more than one.
+             */
+            if (brp->basf.index >= 0) {
+                avpriv_request_sample(s, "Multiple BASF streams");
+                ret = AVERROR_PATCHWELCOME;
+                goto fail;
+            }
+
+            st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
+            st->codecpar->codec_id   = AV_CODEC_ID_ADPCM_ARGO;
+            brp->basf.index          = i;
+            ff_argo_asf_parse_file_header(&hdr->extradata.basf, buf);
+
+            if ((ret = ff_argo_asf_validate_file_header(s, &hdr->extradata.basf)) < 0)
+                goto fail;
+
+        } else {
+            av_assert0(0); /* Caught above, should never happen. */
+        }
+    }
+
+    /*
+     * This is nasty. BASF streams only have one (huge) block.
+     * It should be the first one. It contains the chunk header, so
+     * it needs to be read here.
+     */
+    if (brp->basf.index >= 0) {
+        AVStream *st = s->streams[brp->basf.index];
+        ArgoBRPStreamHeader *hdr = brp->streams + brp->basf.index;
+        ArgoBRPBlockHeader blk;
+
+        av_assert0(st->codecpar->codec_id == AV_CODEC_ID_ADPCM_ARGO);
+        av_assert0(brp->streams[brp->basf.index].extradata_size == ASF_FILE_HEADER_SIZE);
+
+        if ((ret = avio_read(pb, buf, BRP_BLOCK_HEADER_SIZE)) < 0)
+            goto fail;
+        else if (ret != BRP_BLOCK_HEADER_SIZE) {
+            ret = AVERROR(EIO);
+            goto fail;
+        }
+
+        blk.stream_id = AV_RL32(buf + 0);
+        blk.start_ms  = AV_RL32(buf + 4);
+        blk.size      = AV_RL32(buf + 8);
+
+        if (blk.stream_id != brp->basf.index) {
+            avpriv_request_sample(st, "first block not BASF");
+            ret = AVERROR_PATCHWELCOME;
+            goto fail;
+        }
+
+        if (blk.size < ASF_CHUNK_HEADER_SIZE) {
+            ret = AVERROR_INVALIDDATA;
+            goto fail;
+        }
+
+        if ((ret = avio_read(pb, buf, ASF_CHUNK_HEADER_SIZE)) < 0)
+            goto fail;
+        else if (ret != ASF_CHUNK_HEADER_SIZE) {
+            ret = AVERROR(EIO);
+            goto fail;
+        }
+
+        ff_argo_asf_parse_chunk_header(&brp->basf.ckhdr, buf);
+
+        if ((ret = ff_argo_asf_fill_stream(st, &hdr->extradata.basf, &brp->basf.ckhdr)) < 0)
+            goto fail;
+
+        /* Convert ms to samples. */
+        st->start_time = (blk.start_ms * st->codecpar->sample_rate) / 1000;
+
+        if ((ret = avio_tell(s->pb)) < 0)
+            goto fail;
+
+        brp->basf.offset = ret;
+
+        if ((ret = avio_skip(s->pb, blk.size - ASF_CHUNK_HEADER_SIZE)) < 0)
+            goto fail;
+    }
+    return 0;
+
+fail:
+    /* TODO: Remove once AVFMT_HEADER_CLEANUP lands. */
+    argo_brp_read_close(s);
+    return ret;
+}
+
+static int argo_brp_read_basf(AVFormatContext *s, AVPacket *pkt,
+                              ArgoBRPDemuxContext *brp, int ignorepts)
+{
+    ArgoASFChunkHeader *ckhdr = &brp->basf.ckhdr;
+    AVCodecParameters *par;
+    int64_t ret, old;
+
+    if (brp->basf.index < 0)
+        return 0;
+
+    par = s->streams[brp->basf.index]->codecpar;
+
+    if (brp->basf.blocks_read >= ckhdr->num_blocks)
+        return 0;
+
+    if (!ignorepts && brp->lastpts < brp->basf.lastpts)
+        return 0;
+
+    if ((ret = avio_tell(s->pb)) < 0)
+        return ret;
+
+    old = ret;
+
+    if ((ret = avio_seek(s->pb, brp->basf.offset, SEEK_SET)) < 0)
+        return ret;
+    else if (ret != brp->basf.offset)
+        return AVERROR(EIO);
+
+    if ((ret = av_get_packet(s->pb, pkt, par->frame_size)) < 0)
+        return ret;
+
+    if ((ret = avio_seek(s->pb, old, SEEK_SET)) < 0)
+        return ret;
+    else if (ret != old)
+        return AVERROR(EIO);
+
+    pkt->stream_index      = brp->basf.index;
+    pkt->duration          = ckhdr->num_samples;
+
+    brp->basf.offset      += pkt->size;
+    brp->basf.blocks_read += 1;
+    /* Need the ceil() because ((32 * 1000) / 44100) < 1 */
+    brp->basf.lastpts     += ceilf((ckhdr->num_samples * 1000.0f) / ckhdr->sample_rate);
+    return 1;
+}
+
+static int argo_brp_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    ArgoBRPDemuxContext *brp = s->priv_data;
+    ArgoBRPBlockHeader blk;
+    AVIOContext *pb = s->pb;
+    uint8_t buf[BRP_BLOCK_HEADER_SIZE];
+    int ret;
+
+    /*
+     * Special-case: send some more BASF content if we're running behind.
+     * Grr, why couldn't they just interleave it.
+     */
+    if ((ret = argo_brp_read_basf(s, pkt, brp, brp->hit_eof)) < 0)
+        return ret;
+    else if (ret > 0)
+        return 0;
+
+    if (brp->hit_eof)
+        return AVERROR_EOF;
+
+    if ((ret = avio_read(pb, buf, BRP_BLOCK_HEADER_SIZE)) < 0)
+        return ret;
+    else if (ret != BRP_BLOCK_HEADER_SIZE)
+        return AVERROR(EIO);
+
+    blk.stream_id = AV_RL32(buf + 0);
+    blk.start_ms  = AV_RL32(buf + 4);
+    blk.size      = AV_RL32(buf + 8);
+
+    /* This is meant to be EOF, but there might be more BASF packets. */
+    if (blk.stream_id == -1) {
+        brp->hit_eof = 1;
+        /* This is nasty, but safe. */
+        return argo_brp_read_packet(s, pkt);
+    }
+
+    if (blk.stream_id < -1 || blk.stream_id >= s->nb_streams)
+        return AVERROR_INVALIDDATA;
+
+    /* Skip BASF blocks. */
+    if (blk.stream_id == brp->basf.index) {
+        if ((ret = avio_skip(s->pb, blk.size)) < 0)
+            return ret;
+    } else {
+        if ((ret = av_get_packet(s->pb, pkt, blk.size)) < 0)
+            return ret;
+        else if (ret != blk.size)
+            return AVERROR_INVALIDDATA;
+    }
+
+    pkt->stream_index = blk.stream_id;
+    pkt->pts          = blk.start_ms;
+    brp->lastpts      = FFMAX(brp->lastpts, blk.start_ms);
+    return 0;
+}
+
+AVInputFormat ff_argo_brp_demuxer = {
+    .name           = "argo_brp",
+    .long_name      = NULL_IF_CONFIG_SMALL("Argonaut Games BRP"),
+    .priv_data_size = sizeof(ArgoBRPDemuxContext),
+    .read_probe     = argo_brp_probe,
+    .read_header    = argo_brp_read_header,
+    .read_packet    = argo_brp_read_packet,
+    .read_close     = argo_brp_read_close
+};
diff --git a/libavformat/version.h b/libavformat/version.h
index ec3286e73a..641d06d92d 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  55
+#define LIBAVFORMAT_VERSION_MINOR  56
 #define LIBAVFORMAT_VERSION_MICRO 100
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \