diff --git a/Changelog b/Changelog
index e986327172..d905e5dc45 100644
--- a/Changelog
+++ b/Changelog
@@ -6,6 +6,7 @@ version <next>:
 - MacCaption demuxer
 - PGX decoder
 - ADPCM IMA Ubisoft APM encoder
+- Rayman 2 APM muxer
 
 
 version 4.3:
diff --git a/libavformat/Makefile b/libavformat/Makefile
index a4113fe644..62d8cbb54e 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -94,6 +94,7 @@ OBJS-$(CONFIG_ANM_DEMUXER)               += anm.o
 OBJS-$(CONFIG_APC_DEMUXER)               += apc.o
 OBJS-$(CONFIG_APE_DEMUXER)               += ape.o apetag.o img2.o
 OBJS-$(CONFIG_APM_DEMUXER)               += apm.o
+OBJS-$(CONFIG_APM_MUXER)                 += apm.o rawenc.o
 OBJS-$(CONFIG_APNG_DEMUXER)              += apngdec.o
 OBJS-$(CONFIG_APNG_MUXER)                += apngenc.o
 OBJS-$(CONFIG_APTX_DEMUXER)              += aptxdec.o rawdec.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index f8527b1fd4..fd9e46e233 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -55,6 +55,7 @@ extern AVInputFormat  ff_anm_demuxer;
 extern AVInputFormat  ff_apc_demuxer;
 extern AVInputFormat  ff_ape_demuxer;
 extern AVInputFormat  ff_apm_demuxer;
+extern AVOutputFormat ff_apm_muxer;
 extern AVInputFormat  ff_apng_demuxer;
 extern AVOutputFormat ff_apng_muxer;
 extern AVInputFormat  ff_aptx_demuxer;
diff --git a/libavformat/apm.c b/libavformat/apm.c
index 0d88e1099a..d060e526e0 100644
--- a/libavformat/apm.c
+++ b/libavformat/apm.c
@@ -1,5 +1,5 @@
 /*
- * Rayman 2 APM Demuxer
+ * Rayman 2 APM (De)muxer
  *
  * Copyright (C) 2020 Zane van Iperen (zane@zanevaniperen.com)
  *
@@ -21,6 +21,8 @@
  */
 #include "avformat.h"
 #include "internal.h"
+#include "rawenc.h"
+#include "libavutil/avassert.h"
 #include "libavutil/internal.h"
 #include "libavutil/intreadwrite.h"
 
@@ -55,6 +57,7 @@ typedef struct APMExtraData {
     uint32_t    data;
 } APMExtraData;
 
+#if CONFIG_APM_DEMUXER
 static void apm_parse_extradata(APMExtraData *ext, const uint8_t *buf)
 {
     ext->magic              = AV_RL32(buf + 0);
@@ -205,3 +208,105 @@ AVInputFormat ff_apm_demuxer = {
     .read_header    = apm_read_header,
     .read_packet    = apm_read_packet
 };
+#endif
+
+#if CONFIG_APM_MUXER
+static int apm_write_init(AVFormatContext *s)
+{
+    AVCodecParameters *par;
+
+    if (s->nb_streams != 1) {
+        av_log(s, AV_LOG_ERROR, "APM files have exactly one stream\n");
+        return AVERROR(EINVAL);
+    }
+
+    par = s->streams[0]->codecpar;
+
+    if (par->codec_id != AV_CODEC_ID_ADPCM_IMA_APM) {
+        av_log(s, AV_LOG_ERROR, "%s codec not supported\n",
+               avcodec_get_name(par->codec_id));
+        return AVERROR(EINVAL);
+    }
+
+    if (par->channels > 2) {
+        av_log(s, AV_LOG_ERROR, "APM files only support up to 2 channels\n");
+        return AVERROR(EINVAL);
+    }
+
+    if (par->extradata_size != APM_EXTRADATA_SIZE) {
+        av_log(s, AV_LOG_ERROR, "Invalid/missing extradata\n");
+        return AVERROR(EINVAL);
+    }
+
+    if (!(s->pb->seekable & AVIO_SEEKABLE_NORMAL)) {
+        av_log(s, AV_LOG_ERROR, "Stream not seekable, unable to write output file\n");
+        return AVERROR(EINVAL);
+    }
+
+    return 0;
+}
+
+static int apm_write_header(AVFormatContext *s)
+{
+    uint8_t buf[APM_FILE_EXTRADATA_SIZE] = { 0 };
+    AVCodecParameters *par = s->streams[0]->codecpar;
+
+    /*
+     * Bodge a WAVEFORMATEX manually, ff_put_wav_header() can't
+     * be used because of the extra 2 bytes.
+     */
+    avio_wl16(s->pb, APM_TAG_CODEC);
+    avio_wl16(s->pb, par->channels);
+    avio_wl32(s->pb, par->sample_rate);
+    /* This is the wrong calculation, but it's what the orginal files have. */
+    avio_wl32(s->pb, par->sample_rate * par->channels * 2);
+    avio_wl16(s->pb, par->block_align);
+    avio_wl16(s->pb, par->bits_per_coded_sample);
+    avio_wl32(s->pb, APM_FILE_EXTRADATA_SIZE);
+
+    /*
+     * Build the extradata. Assume the codec's given us correct data.
+     * File and data sizes are fixed later.
+     */
+    AV_WL32(buf +  0, APM_TAG_VS12); /* magic */
+    AV_WL32(buf + 12, 0xFFFFFFFF);   /* unk1  */
+    memcpy( buf + 20, par->extradata, APM_EXTRADATA_SIZE);
+    AV_WL32(buf + 76, APM_TAG_DATA); /* data */
+
+    avio_write(s->pb, buf, APM_FILE_EXTRADATA_SIZE);
+    return 0;
+}
+
+static int apm_write_trailer(AVFormatContext *s)
+{
+    int64_t file_size, data_size;
+
+    file_size = avio_tell(s->pb);
+    data_size = file_size - (APM_FILE_HEADER_SIZE + 2 + APM_FILE_EXTRADATA_SIZE);
+
+    if (file_size >= UINT32_MAX) {
+        av_log(s, AV_LOG_ERROR,
+               "Filesize %"PRId64" invalid for APM, output file will be broken\n",
+               file_size);
+        return AVERROR(ERANGE);
+    }
+
+    avio_seek(s->pb, 24, SEEK_SET);
+    avio_wl32(s->pb, (uint32_t)file_size);
+    avio_wl32(s->pb, (uint32_t)data_size);
+
+    return 0;
+}
+
+AVOutputFormat ff_apm_muxer = {
+    .name           = "apm",
+    .long_name      = NULL_IF_CONFIG_SMALL("Ubisoft Rayman 2 APM"),
+    .extensions     = "apm",
+    .audio_codec    = AV_CODEC_ID_ADPCM_IMA_APM,
+    .video_codec    = AV_CODEC_ID_NONE,
+    .init           = apm_write_init,
+    .write_header   = apm_write_header,
+    .write_packet   = ff_raw_write_packet,
+    .write_trailer  = apm_write_trailer
+};
+#endif
diff --git a/libavformat/version.h b/libavformat/version.h
index 75c03fde0a..33cebed85e 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  48
+#define LIBAVFORMAT_VERSION_MINOR  49
 #define LIBAVFORMAT_VERSION_MICRO 100
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
