[FFmpeg-devel,1/2] avcodec: add MatchWare Screen Capture Codec

Submitted by Paul B Mahol on Aug. 25, 2018, 8:03 p.m.

Details

Message ID 20180825200356.28361-1-onemda@gmail.com
State New
Headers show

Commit Message

Paul B Mahol Aug. 25, 2018, 8:03 p.m.
Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 configure               |   1 +
 libavcodec/Makefile     |   1 +
 libavcodec/allcodecs.c  |   1 +
 libavcodec/avcodec.h    |   1 +
 libavcodec/codec_desc.c |   7 ++
 libavcodec/mwsc.c       | 192 ++++++++++++++++++++++++++++++++++++++++
 libavformat/riff.c      |   1 +
 7 files changed, 204 insertions(+)
 create mode 100644 libavcodec/mwsc.c

Comments

Rostislav Pehlivanov Aug. 27, 2018, 6:20 p.m.
On Sat, 25 Aug 2018 at 21:04, Paul B Mahol <onemda@gmail.com> wrote:

> Signed-off-by: Paul B Mahol <onemda@gmail.com>
> ---
>  configure               |   1 +
>  libavcodec/Makefile     |   1 +
>  libavcodec/allcodecs.c  |   1 +
>  libavcodec/avcodec.h    |   1 +
>  libavcodec/codec_desc.c |   7 ++
>  libavcodec/mwsc.c       | 192 ++++++++++++++++++++++++++++++++++++++++
>  libavformat/riff.c      |   1 +
>  7 files changed, 204 insertions(+)
>  create mode 100644 libavcodec/mwsc.c
>
> diff --git a/configure b/configure
> index b9c9d0b307..0c1f6a79a7 100755
> --- a/configure
> +++ b/configure
> @@ -2679,6 +2679,7 @@ msmpeg4v3_decoder_select="h263_decoder"
>  msmpeg4v3_encoder_select="h263_encoder"
>  mss2_decoder_select="mpegvideo qpeldsp vc1_decoder"
>  mts2_decoder_select="mss34dsp"
> +mwsc_decoder_deps="zlib"
>  mxpeg_decoder_select="mjpeg_decoder"
>  nellymoser_decoder_select="mdct sinewin"
>  nellymoser_encoder_select="audio_frame_queue mdct sinewin"
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 9a309c348e..aee4f5431a 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -482,6 +482,7 @@ OBJS-$(CONFIG_MSZH_DECODER)            += lcldec.o
>  OBJS-$(CONFIG_MTS2_DECODER)            += mss4.o
>  OBJS-$(CONFIG_MVC1_DECODER)            += mvcdec.o
>  OBJS-$(CONFIG_MVC2_DECODER)            += mvcdec.o
> +OBJS-$(CONFIG_MWSC_DECODER)            += mwsc.o
>  OBJS-$(CONFIG_MXPEG_DECODER)           += mxpegdec.o
>  OBJS-$(CONFIG_NELLYMOSER_DECODER)      += nellymoserdec.o nellymoser.o
>  OBJS-$(CONFIG_NELLYMOSER_ENCODER)      += nellymoserenc.o nellymoser.o
> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
> index b1d1ef26c0..d41868c591 100644
> --- a/libavcodec/allcodecs.c
> +++ b/libavcodec/allcodecs.c
> @@ -212,6 +212,7 @@ extern AVCodec ff_mszh_decoder;
>  extern AVCodec ff_mts2_decoder;
>  extern AVCodec ff_mvc1_decoder;
>  extern AVCodec ff_mvc2_decoder;
> +extern AVCodec ff_mwsc_decoder;
>  extern AVCodec ff_mxpeg_decoder;
>  extern AVCodec ff_nuv_decoder;
>  extern AVCodec ff_paf_video_decoder;
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index 86a658a233..be41b8cf0e 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -449,6 +449,7 @@ enum AVCodecID {
>      AV_CODEC_ID_FITS,
>      AV_CODEC_ID_IMM4,
>      AV_CODEC_ID_PROSUMER,
> +    AV_CODEC_ID_MWSC,
>
>      /* 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 e611183599..129d0f1aac 100644
> --- a/libavcodec/codec_desc.c
> +++ b/libavcodec/codec_desc.c
> @@ -1668,6 +1668,13 @@ static const AVCodecDescriptor codec_descriptors[]
> = {
>          .long_name = NULL_IF_CONFIG_SMALL("Brooktree ProSumer Video"),
>          .props     = AV_CODEC_PROP_INTRA_ONLY | AV_CODEC_PROP_LOSSY,
>      },
> +    {
> +        .id        = AV_CODEC_ID_MWSC,
> +        .type      = AVMEDIA_TYPE_VIDEO,
> +        .name      = "mwsc",
> +        .long_name = NULL_IF_CONFIG_SMALL("MatchWare Screen Capture
> Codec"),
> +        .props     = AV_CODEC_PROP_LOSSLESS,
> +    },
>
>      /* various PCM "codecs" */
>      {
> diff --git a/libavcodec/mwsc.c b/libavcodec/mwsc.c
> new file mode 100644
> index 0000000000..c1a5aca3c0
> --- /dev/null
> +++ b/libavcodec/mwsc.c
> @@ -0,0 +1,192 @@
> +/*
> + * MatchWare Screen Capture Codec 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 MWSCContext {
> +    unsigned int      decomp_size;
> +    uint8_t          *decomp_buf;
> +    z_stream          zstream;
> +    AVFrame          *prev_frame;
> +} MWSCContext;
> +
> +static int rle_uncompress(GetByteContext *gb, PutByteContext *pb,
> GetByteContext *gbp,
> +                          int width, int height, int stride, int
> pb_linesize, int gbp_linesize)
> +{
> +    int intra = 1, w = 0;
> +
> +    bytestream2_seek_p(pb, (height - 1) * pb_linesize, SEEK_SET);
> +
> +    while (bytestream2_get_bytes_left(gb) > 0) {
> +        uint32_t fill = bytestream2_get_le24(gb);
> +        unsigned run = bytestream2_get_byte(gb);
> +
> +        if (run == 0) {
> +            run = bytestream2_get_le32(gb);
> +            for (int j = 0; j < run; j++, w++) {
> +                if (w == width) {
> +                    w = 0;
> +                    bytestream2_seek_p(pb, -(pb_linesize + stride),
> SEEK_CUR);
> +                }
> +                bytestream2_put_le24(pb, fill);
> +            }
> +        } else if (run == 255) {
> +            int pos = bytestream2_tell_p(pb);
> +
> +            bytestream2_seek(gbp, pos, SEEK_SET);
> +            for (int j = 0; j < fill; j++, w++) {
> +                if (w == width) {
> +                    w = 0;
> +                    bytestream2_seek_p(pb, -(pb_linesize + stride),
> SEEK_CUR);
> +                    bytestream2_seek(gbp, -(gbp_linesize + stride),
> SEEK_CUR);
> +                }
> +                bytestream2_put_le24(pb, bytestream2_get_le24(gbp));
> +            }
> +
> +            intra = 0;
> +        } else {
> +            for (int j = 0; j < run; j++, w++) {
> +                if (w == width) {
> +                    w = 0;
> +                    bytestream2_seek_p(pb, -(pb_linesize + stride),
> SEEK_CUR);
> +                }
> +                bytestream2_put_le24(pb, fill);
> +            }
> +        }
> +    }
> +
> +    return intra;
> +}
> +
> +static int decode_frame(AVCodecContext *avctx,
> +                        void *data, int *got_frame,
> +                        AVPacket *avpkt)
> +{
> +    MWSCContext *s = avctx->priv_data;
> +    AVFrame *frame = data;
> +    uint8_t *buf = avpkt->data;
> +    int buf_size = avpkt->size;
> +    GetByteContext gb;
> +    GetByteContext gbp;
> +    PutByteContext pb;
> +    int ret;
>

Can you check that avpkt->size isn't larger than the deflate buffer you've
allocated?


+
>
+    ret = inflateReset(&s->zstream);
> +    if (ret != Z_OK) {
> +        av_log(avctx, AV_LOG_ERROR, "Inflate reset error: %d\n", ret);
> +        return AVERROR_EXTERNAL;
> +    }
> +    s->zstream.next_in   = buf;
> +    s->zstream.avail_in  = buf_size;
> +    s->zstream.next_out  = s->decomp_buf;
> +    s->zstream.avail_out = s->decomp_size;
> +    ret = inflate(&s->zstream, Z_FINISH);
> +    if (ret != Z_STREAM_END) {
> +        av_log(avctx, AV_LOG_ERROR, "Inflate error: %d\n", ret);
> +        return AVERROR_EXTERNAL;
> +    }
> +
> +    if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
> +        return ret;
> +
> +    bytestream2_init(&gb, s->decomp_buf, s->zstream.total_out);
> +    bytestream2_init(&gbp, s->prev_frame->data[0], avctx->height *
> frame->linesize[0]);
> +    bytestream2_init_writer(&pb, frame->data[0], avctx->height *
> frame->linesize[0]);
> +
> +    frame->key_frame = rle_uncompress(&gb, &pb, &gbp, avctx->width,
> avctx->height, avctx->width * 3,
> +                                      frame->linesize[0],
> s->prev_frame->linesize[0]);
> +
> +    frame->pict_type = frame->key_frame ? 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)
> +{
> +    MWSCContext *s = avctx->priv_data;
> +    int64_t size;
> +    int zret;
> +
> +    avctx->pix_fmt = AV_PIX_FMT_BGR24;
> +
> +    size = 8LL * avctx->height * ((avctx->width *
> avctx->bits_per_coded_sample + 31) / 32);
>

What sets bits_per_coded_samples? lavf/riff?


+    if (size >= INT32_MAX)
> +        return AVERROR_INVALIDDATA;
> +    s->decomp_size = size;
> +    if (!(s->decomp_buf = av_malloc(s->decomp_size)))
> +        return AVERROR(ENOMEM);
> +
> +    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)
> +{
> +    MWSCContext *s = avctx->priv_data;
> +
> +    av_frame_free(&s->prev_frame);
> +    av_freep(&s->decomp_buf);
> +    s->decomp_size = 0;
> +    inflateEnd(&s->zstream);
> +
> +    return 0;
> +}
> +
> +AVCodec ff_mwsc_decoder = {
> +    .name             = "mwsc",
> +    .long_name        = NULL_IF_CONFIG_SMALL("MatchWare Screen Capture
> Codec"),
> +    .type             = AVMEDIA_TYPE_VIDEO,
> +    .id               = AV_CODEC_ID_MWSC,
> +    .priv_data_size   = sizeof(MWSCContext),
> +    .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 cf27d0dfd5..aef3c047ac 100644
> --- a/libavformat/riff.c
> +++ b/libavformat/riff.c
> @@ -472,6 +472,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
>      { AV_CODEC_ID_SRGC,         MKTAG('S', 'R', 'G', 'C') },
>      { 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_NONE,         0 }
>  };
>
> --
> 2.17.1
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel


Apart from that I can't find something else that seems wrong. Just bump
lavc micro and put in a line in the changelog.
Rostislav Pehlivanov Aug. 27, 2018, 6:33 p.m.
On Mon, 27 Aug 2018 at 19:20, Rostislav Pehlivanov <atomnuker@gmail.com>
wrote:

>
>
> On Sat, 25 Aug 2018 at 21:04, Paul B Mahol <onemda@gmail.com> wrote:
>
>> Signed-off-by: Paul B Mahol <onemda@gmail.com>
>> ---
>>  configure               |   1 +
>>  libavcodec/Makefile     |   1 +
>>  libavcodec/allcodecs.c  |   1 +
>>  libavcodec/avcodec.h    |   1 +
>>  libavcodec/codec_desc.c |   7 ++
>>  libavcodec/mwsc.c       | 192 ++++++++++++++++++++++++++++++++++++++++
>>  libavformat/riff.c      |   1 +
>>  7 files changed, 204 insertions(+)
>>  create mode 100644 libavcodec/mwsc.c
>>
>> +static int decode_frame(AVCodecContext *avctx,
>> +                        void *data, int *got_frame,
>> +                        AVPacket *avpkt)
>> +{
>> +    MWSCContext *s = avctx->priv_data;
>> +    AVFrame *frame = data;
>> +    uint8_t *buf = avpkt->data;
>> +    int buf_size = avpkt->size;
>> +    GetByteContext gb;
>> +    GetByteContext gbp;
>> +    PutByteContext pb;
>> +    int ret;
>>
>
> Can you check that avpkt->size isn't larger than the deflate buffer you've
> allocated?
>

If zlib checks that the buffer size is smaller than what it has to unpack
don't, same as the wincam decoder.

Patch hide | download patch | download mbox

diff --git a/configure b/configure
index b9c9d0b307..0c1f6a79a7 100755
--- a/configure
+++ b/configure
@@ -2679,6 +2679,7 @@  msmpeg4v3_decoder_select="h263_decoder"
 msmpeg4v3_encoder_select="h263_encoder"
 mss2_decoder_select="mpegvideo qpeldsp vc1_decoder"
 mts2_decoder_select="mss34dsp"
+mwsc_decoder_deps="zlib"
 mxpeg_decoder_select="mjpeg_decoder"
 nellymoser_decoder_select="mdct sinewin"
 nellymoser_encoder_select="audio_frame_queue mdct sinewin"
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 9a309c348e..aee4f5431a 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -482,6 +482,7 @@  OBJS-$(CONFIG_MSZH_DECODER)            += lcldec.o
 OBJS-$(CONFIG_MTS2_DECODER)            += mss4.o
 OBJS-$(CONFIG_MVC1_DECODER)            += mvcdec.o
 OBJS-$(CONFIG_MVC2_DECODER)            += mvcdec.o
+OBJS-$(CONFIG_MWSC_DECODER)            += mwsc.o
 OBJS-$(CONFIG_MXPEG_DECODER)           += mxpegdec.o
 OBJS-$(CONFIG_NELLYMOSER_DECODER)      += nellymoserdec.o nellymoser.o
 OBJS-$(CONFIG_NELLYMOSER_ENCODER)      += nellymoserenc.o nellymoser.o
diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
index b1d1ef26c0..d41868c591 100644
--- a/libavcodec/allcodecs.c
+++ b/libavcodec/allcodecs.c
@@ -212,6 +212,7 @@  extern AVCodec ff_mszh_decoder;
 extern AVCodec ff_mts2_decoder;
 extern AVCodec ff_mvc1_decoder;
 extern AVCodec ff_mvc2_decoder;
+extern AVCodec ff_mwsc_decoder;
 extern AVCodec ff_mxpeg_decoder;
 extern AVCodec ff_nuv_decoder;
 extern AVCodec ff_paf_video_decoder;
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 86a658a233..be41b8cf0e 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -449,6 +449,7 @@  enum AVCodecID {
     AV_CODEC_ID_FITS,
     AV_CODEC_ID_IMM4,
     AV_CODEC_ID_PROSUMER,
+    AV_CODEC_ID_MWSC,
 
     /* 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 e611183599..129d0f1aac 100644
--- a/libavcodec/codec_desc.c
+++ b/libavcodec/codec_desc.c
@@ -1668,6 +1668,13 @@  static const AVCodecDescriptor codec_descriptors[] = {
         .long_name = NULL_IF_CONFIG_SMALL("Brooktree ProSumer Video"),
         .props     = AV_CODEC_PROP_INTRA_ONLY | AV_CODEC_PROP_LOSSY,
     },
+    {
+        .id        = AV_CODEC_ID_MWSC,
+        .type      = AVMEDIA_TYPE_VIDEO,
+        .name      = "mwsc",
+        .long_name = NULL_IF_CONFIG_SMALL("MatchWare Screen Capture Codec"),
+        .props     = AV_CODEC_PROP_LOSSLESS,
+    },
 
     /* various PCM "codecs" */
     {
diff --git a/libavcodec/mwsc.c b/libavcodec/mwsc.c
new file mode 100644
index 0000000000..c1a5aca3c0
--- /dev/null
+++ b/libavcodec/mwsc.c
@@ -0,0 +1,192 @@ 
+/*
+ * MatchWare Screen Capture Codec 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 MWSCContext {
+    unsigned int      decomp_size;
+    uint8_t          *decomp_buf;
+    z_stream          zstream;
+    AVFrame          *prev_frame;
+} MWSCContext;
+
+static int rle_uncompress(GetByteContext *gb, PutByteContext *pb, GetByteContext *gbp,
+                          int width, int height, int stride, int pb_linesize, int gbp_linesize)
+{
+    int intra = 1, w = 0;
+
+    bytestream2_seek_p(pb, (height - 1) * pb_linesize, SEEK_SET);
+
+    while (bytestream2_get_bytes_left(gb) > 0) {
+        uint32_t fill = bytestream2_get_le24(gb);
+        unsigned run = bytestream2_get_byte(gb);
+
+        if (run == 0) {
+            run = bytestream2_get_le32(gb);
+            for (int j = 0; j < run; j++, w++) {
+                if (w == width) {
+                    w = 0;
+                    bytestream2_seek_p(pb, -(pb_linesize + stride), SEEK_CUR);
+                }
+                bytestream2_put_le24(pb, fill);
+            }
+        } else if (run == 255) {
+            int pos = bytestream2_tell_p(pb);
+
+            bytestream2_seek(gbp, pos, SEEK_SET);
+            for (int j = 0; j < fill; j++, w++) {
+                if (w == width) {
+                    w = 0;
+                    bytestream2_seek_p(pb, -(pb_linesize + stride), SEEK_CUR);
+                    bytestream2_seek(gbp, -(gbp_linesize + stride), SEEK_CUR);
+                }
+                bytestream2_put_le24(pb, bytestream2_get_le24(gbp));
+            }
+
+            intra = 0;
+        } else {
+            for (int j = 0; j < run; j++, w++) {
+                if (w == width) {
+                    w = 0;
+                    bytestream2_seek_p(pb, -(pb_linesize + stride), SEEK_CUR);
+                }
+                bytestream2_put_le24(pb, fill);
+            }
+        }
+    }
+
+    return intra;
+}
+
+static int decode_frame(AVCodecContext *avctx,
+                        void *data, int *got_frame,
+                        AVPacket *avpkt)
+{
+    MWSCContext *s = avctx->priv_data;
+    AVFrame *frame = data;
+    uint8_t *buf = avpkt->data;
+    int buf_size = avpkt->size;
+    GetByteContext gb;
+    GetByteContext gbp;
+    PutByteContext pb;
+    int ret;
+
+    ret = inflateReset(&s->zstream);
+    if (ret != Z_OK) {
+        av_log(avctx, AV_LOG_ERROR, "Inflate reset error: %d\n", ret);
+        return AVERROR_EXTERNAL;
+    }
+    s->zstream.next_in   = buf;
+    s->zstream.avail_in  = buf_size;
+    s->zstream.next_out  = s->decomp_buf;
+    s->zstream.avail_out = s->decomp_size;
+    ret = inflate(&s->zstream, Z_FINISH);
+    if (ret != Z_STREAM_END) {
+        av_log(avctx, AV_LOG_ERROR, "Inflate error: %d\n", ret);
+        return AVERROR_EXTERNAL;
+    }
+
+    if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
+        return ret;
+
+    bytestream2_init(&gb, s->decomp_buf, s->zstream.total_out);
+    bytestream2_init(&gbp, s->prev_frame->data[0], avctx->height * frame->linesize[0]);
+    bytestream2_init_writer(&pb, frame->data[0], avctx->height * frame->linesize[0]);
+
+    frame->key_frame = rle_uncompress(&gb, &pb, &gbp, avctx->width, avctx->height, avctx->width * 3,
+                                      frame->linesize[0], s->prev_frame->linesize[0]);
+
+    frame->pict_type = frame->key_frame ? 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)
+{
+    MWSCContext *s = avctx->priv_data;
+    int64_t size;
+    int zret;
+
+    avctx->pix_fmt = AV_PIX_FMT_BGR24;
+
+    size = 8LL * avctx->height * ((avctx->width * avctx->bits_per_coded_sample + 31) / 32);
+    if (size >= INT32_MAX)
+        return AVERROR_INVALIDDATA;
+    s->decomp_size = size;
+    if (!(s->decomp_buf = av_malloc(s->decomp_size)))
+        return AVERROR(ENOMEM);
+
+    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)
+{
+    MWSCContext *s = avctx->priv_data;
+
+    av_frame_free(&s->prev_frame);
+    av_freep(&s->decomp_buf);
+    s->decomp_size = 0;
+    inflateEnd(&s->zstream);
+
+    return 0;
+}
+
+AVCodec ff_mwsc_decoder = {
+    .name             = "mwsc",
+    .long_name        = NULL_IF_CONFIG_SMALL("MatchWare Screen Capture Codec"),
+    .type             = AVMEDIA_TYPE_VIDEO,
+    .id               = AV_CODEC_ID_MWSC,
+    .priv_data_size   = sizeof(MWSCContext),
+    .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 cf27d0dfd5..aef3c047ac 100644
--- a/libavformat/riff.c
+++ b/libavformat/riff.c
@@ -472,6 +472,7 @@  const AVCodecTag ff_codec_bmp_tags[] = {
     { AV_CODEC_ID_SRGC,         MKTAG('S', 'R', 'G', 'C') },
     { 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_NONE,         0 }
 };