diff --git a/configure b/configure
index 0c1f6a79a7..469797935e 100755
--- a/configure
+++ b/configure
@@ -2750,6 +2750,7 @@ vp6f_decoder_select="vp6_decoder"
 vp7_decoder_select="h264pred videodsp vp8dsp"
 vp8_decoder_select="h264pred videodsp vp8dsp"
 vp9_decoder_select="videodsp vp9_parser vp9_superframe_split_bsf"
+wcmv_decoder_deps="zlib"
 webp_decoder_select="vp8_decoder exif"
 wmalossless_decoder_select="llauddsp"
 wmapro_decoder_select="mdct sinewin wma_freqs"
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index aee4f5431a..f8673f0121 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -677,6 +677,7 @@ OBJS-$(CONFIG_VP9_V4L2M2M_DECODER)     += v4l2_m2m_dec.o
 OBJS-$(CONFIG_VQA_DECODER)             += vqavideo.o
 OBJS-$(CONFIG_WAVPACK_DECODER)         += wavpack.o
 OBJS-$(CONFIG_WAVPACK_ENCODER)         += wavpackenc.o
+OBJS-$(CONFIG_WCMV_DECODER)            += wcmv.o
 OBJS-$(CONFIG_WEBP_DECODER)            += webp.o
 OBJS-$(CONFIG_WEBVTT_DECODER)          += webvttdec.o ass.o
 OBJS-$(CONFIG_WEBVTT_ENCODER)          += webvttenc.o ass_split.o
diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
index d41868c591..42d98f9b0a 100644
--- a/libavcodec/allcodecs.c
+++ b/libavcodec/allcodecs.c
@@ -338,6 +338,7 @@ extern AVCodec ff_vp9_v4l2m2m_decoder;
 extern AVCodec ff_vqa_decoder;
 extern AVCodec ff_bitpacked_decoder;
 extern AVCodec ff_webp_decoder;
+extern AVCodec ff_wcmv_decoder;
 extern AVCodec ff_wrapped_avframe_encoder;
 extern AVCodec ff_wrapped_avframe_decoder;
 extern AVCodec ff_wmv1_encoder;
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index be41b8cf0e..b6688b7af3 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -450,6 +450,7 @@ enum AVCodecID {
     AV_CODEC_ID_IMM4,
     AV_CODEC_ID_PROSUMER,
     AV_CODEC_ID_MWSC,
+    AV_CODEC_ID_WCMV,
 
     /* various PCM "codecs" */
     AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs
diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
index 129d0f1aac..46dfe3f5e5 100644
--- a/libavcodec/codec_desc.c
+++ b/libavcodec/codec_desc.c
@@ -1675,6 +1675,13 @@ static const AVCodecDescriptor codec_descriptors[] = {
         .long_name = NULL_IF_CONFIG_SMALL("MatchWare Screen Capture Codec"),
         .props     = AV_CODEC_PROP_LOSSLESS,
     },
+    {
+        .id        = AV_CODEC_ID_WCMV,
+        .type      = AVMEDIA_TYPE_VIDEO,
+        .name      = "wcmv",
+        .long_name = NULL_IF_CONFIG_SMALL("WinCAM Motion Video"),
+        .props     = AV_CODEC_PROP_LOSSLESS,
+    },
 
     /* various PCM "codecs" */
     {
diff --git a/libavcodec/wcmv.c b/libavcodec/wcmv.c
new file mode 100644
index 0000000000..74cb1166bb
--- /dev/null
+++ b/libavcodec/wcmv.c
@@ -0,0 +1,247 @@
+/*
+ * WinCAM Motion Video decoder
+ *
+ * Copyright (c) 2018 Paul B Mahol
+ *
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "avcodec.h"
+#include "bytestream.h"
+#include "internal.h"
+
+#include <zlib.h>
+
+typedef struct WCMVContext {
+    z_stream    zstream;
+    AVFrame    *prev_frame;
+    uint8_t     block_data[65536*8];
+} WCMVContext;
+
+static int decode_frame(AVCodecContext *avctx,
+                        void *data, int *got_frame,
+                        AVPacket *avpkt)
+{
+    WCMVContext *s = avctx->priv_data;
+    AVFrame *frame = data;
+    int skip, blocks, zret, ret, intra = 0;
+    GetByteContext gb;
+    uint8_t *dst;
+
+    ret = inflateReset(&s->zstream);
+    if (ret != Z_OK) {
+        av_log(avctx, AV_LOG_ERROR, "Inflate reset error: %d\n", ret);
+        return AVERROR_EXTERNAL;
+    }
+
+    bytestream2_init(&gb, avpkt->data, avpkt->size);
+
+    if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
+        return ret;
+
+    if (s->prev_frame->data[0]) {
+        ret = av_frame_copy(frame, s->prev_frame);
+        if (ret < 0)
+            return ret;
+    }
+
+    blocks = bytestream2_get_le16(&gb);
+    if (blocks > 5) {
+        GetByteContext bgb;
+        int x = 0, size;
+
+        if (blocks * 8 >= 0xFFFF) {
+            size = bytestream2_get_le24(&gb);
+        } else if (blocks * 8 >= 0xFF) {
+            size = bytestream2_get_le16(&gb);
+        } else {
+            size = bytestream2_get_byte(&gb);
+        }
+
+        skip = bytestream2_tell(&gb);
+        if (size > avpkt->size - skip)
+            return AVERROR_INVALIDDATA;
+
+        s->zstream.next_in  = avpkt->data + skip;
+        s->zstream.avail_in = size;
+        s->zstream.next_out  = s->block_data;
+        s->zstream.avail_out = sizeof(s->block_data);
+
+        zret = inflate(&s->zstream, Z_FINISH);
+        if (zret != Z_STREAM_END) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Inflate failed with return code: %d.\n", zret);
+            return AVERROR_INVALIDDATA;
+        }
+
+        ret = inflateReset(&s->zstream);
+        if (ret != Z_OK) {
+            av_log(avctx, AV_LOG_ERROR, "Inflate reset error: %d\n", ret);
+            return AVERROR_EXTERNAL;
+        }
+
+        bytestream2_skip(&gb, size);
+        bytestream2_init(&bgb, s->block_data, blocks * 8);
+
+        for (int i = 0; i < blocks; i++) {
+            int w, h;
+
+            bytestream2_skip(&bgb, 4);
+            w = bytestream2_get_le16(&bgb);
+            h = bytestream2_get_le16(&bgb);
+            x += 3 * w * h;
+        }
+
+        if (x >= 0xFFFF) {
+            bytestream2_skip(&gb, 3);
+        } else if (x >= 0xFF) {
+            bytestream2_skip(&gb, 2);
+        } else {
+            bytestream2_skip(&gb, 1);
+        }
+
+        skip = bytestream2_tell(&gb);
+
+        s->zstream.next_in  = avpkt->data + skip;
+        s->zstream.avail_in = avpkt->size - skip;
+
+        bytestream2_init(&gb, s->block_data, blocks * 8);
+    } else {
+        int x = 0;
+
+        bytestream2_seek(&gb, 2, SEEK_SET);
+
+        for (int i = 0; i < blocks; i++) {
+            int w, h;
+
+            bytestream2_skip(&gb, 4);
+            w = bytestream2_get_le16(&gb);
+            h = bytestream2_get_le16(&gb);
+            x += 3 * w * h;
+        }
+
+        if (x >= 0xFFFF) {
+            bytestream2_skip(&gb, 3);
+        } else if (x >= 0xFF) {
+            bytestream2_skip(&gb, 2);
+        } else {
+            bytestream2_skip(&gb, 1);
+        }
+
+        skip = bytestream2_tell(&gb);
+
+        s->zstream.next_in  = avpkt->data + skip;
+        s->zstream.avail_in = avpkt->size - skip;
+
+        bytestream2_seek(&gb, 2, SEEK_SET);
+    }
+
+    for (int block = 0; block < blocks; block++) {
+        int x, y, w, h;
+
+        x = bytestream2_get_le16(&gb);
+        y = bytestream2_get_le16(&gb);
+        w = bytestream2_get_le16(&gb);
+        h = bytestream2_get_le16(&gb);
+
+        if (blocks == 1 && x == 0 && y == 0 && w == avctx->width && h == avctx->height)
+            intra = 1;
+
+        if (x + w > avctx->width || y + h > avctx->height)
+            return AVERROR_INVALIDDATA;
+
+        if (w > avctx->width || h > avctx->height)
+            return AVERROR_INVALIDDATA;
+
+        dst = frame->data[0] + (avctx->height - y - 1) * frame->linesize[0] + x * 3;
+        for (int i = 0; i < h; i++) {
+            s->zstream.next_out  = dst;
+            s->zstream.avail_out = w * 3;
+
+            zret = inflate(&s->zstream, Z_SYNC_FLUSH);
+            if (zret != Z_OK && zret != Z_STREAM_END) {
+                av_log(avctx, AV_LOG_ERROR,
+                       "Inflate failed with return code: %d.\n", zret);
+                return AVERROR_INVALIDDATA;
+            }
+
+            dst -= frame->linesize[0];
+        }
+    }
+
+    frame->key_frame = intra;
+    frame->pict_type = intra ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
+
+    av_frame_unref(s->prev_frame);
+    if ((ret = av_frame_ref(s->prev_frame, frame)) < 0)
+        return ret;
+
+    *got_frame = 1;
+
+    return avpkt->size;
+}
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+    WCMVContext *s = avctx->priv_data;
+    int zret;
+
+    avctx->pix_fmt = AV_PIX_FMT_BGR24;
+
+    s->zstream.zalloc = Z_NULL;
+    s->zstream.zfree = Z_NULL;
+    s->zstream.opaque = Z_NULL;
+    zret = inflateInit(&s->zstream);
+    if (zret != Z_OK) {
+        av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
+        return AVERROR_EXTERNAL;
+    }
+
+    s->prev_frame = av_frame_alloc();
+    if (!s->prev_frame)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+static av_cold int decode_close(AVCodecContext *avctx)
+{
+    WCMVContext *s = avctx->priv_data;
+
+    av_frame_free(&s->prev_frame);
+    inflateEnd(&s->zstream);
+
+    return 0;
+}
+
+AVCodec ff_wcmv_decoder = {
+    .name             = "wcmv",
+    .long_name        = NULL_IF_CONFIG_SMALL("WinCAM Motion Video"),
+    .type             = AVMEDIA_TYPE_VIDEO,
+    .id               = AV_CODEC_ID_WCMV,
+    .priv_data_size   = sizeof(WCMVContext),
+    .init             = decode_init,
+    .close            = decode_close,
+    .decode           = decode_frame,
+    .capabilities     = AV_CODEC_CAP_DR1,
+    .caps_internal    = FF_CODEC_CAP_INIT_THREADSAFE |
+                        FF_CODEC_CAP_INIT_CLEANUP,
+};
diff --git a/libavformat/riff.c b/libavformat/riff.c
index aef3c047ac..5f1aafe514 100644
--- a/libavformat/riff.c
+++ b/libavformat/riff.c
@@ -473,6 +473,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
     { AV_CODEC_ID_IMM4,         MKTAG('I', 'M', 'M', '4') },
     { AV_CODEC_ID_PROSUMER,     MKTAG('B', 'T', '2', '0') },
     { AV_CODEC_ID_MWSC,         MKTAG('M', 'W', 'S', 'C') },
+    { AV_CODEC_ID_WCMV,         MKTAG('W', 'C', 'M', 'V') },
     { AV_CODEC_ID_NONE,         0 }
 };
 
