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[FFmpeg-devel,2/3] avcodec: add SGA Video decoder

Message ID 20210226112919.20437-2-onemda@gmail.com
State Accepted
Headers show
Series [FFmpeg-devel,1/3] avcodec: add SGA PCM decoder
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Commit Message

Paul B Mahol Feb. 26, 2021, 11:29 a.m. UTC
Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 libavcodec/Makefile     |   1 +
 libavcodec/allcodecs.c  |   1 +
 libavcodec/codec_desc.c |   7 +
 libavcodec/codec_id.h   |   1 +
 libavcodec/sga.c        | 534 ++++++++++++++++++++++++++++++++++++++++
 5 files changed, 544 insertions(+)
 create mode 100644 libavcodec/sga.c

Comments

James Almer Feb. 27, 2021, 3:19 a.m. UTC | #1
On 2/26/2021 8:29 AM, Paul B Mahol wrote:
> Signed-off-by: Paul B Mahol <onemda@gmail.com>
> ---
>   libavcodec/Makefile     |   1 +
>   libavcodec/allcodecs.c  |   1 +
>   libavcodec/codec_desc.c |   7 +
>   libavcodec/codec_id.h   |   1 +
>   libavcodec/sga.c        | 534 ++++++++++++++++++++++++++++++++++++++++
>   5 files changed, 544 insertions(+)
>   create mode 100644 libavcodec/sga.c
> 
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index fe7026c1db..850657ae3c 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -609,6 +609,7 @@ OBJS-$(CONFIG_SANM_DECODER)            += sanm.o
>   OBJS-$(CONFIG_SCPR_DECODER)            += scpr.o
>   OBJS-$(CONFIG_SCREENPRESSO_DECODER)    += screenpresso.o
>   OBJS-$(CONFIG_SDX2_DPCM_DECODER)       += dpcm.o
> +OBJS-$(CONFIG_SGA_DECODER)             += sga.o
>   OBJS-$(CONFIG_SGI_DECODER)             += sgidec.o
>   OBJS-$(CONFIG_SGI_ENCODER)             += sgienc.o rle.o
>   OBJS-$(CONFIG_SGIRLE_DECODER)          += sgirledec.o
> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
> index 990998b64b..a04faead16 100644
> --- a/libavcodec/allcodecs.c
> +++ b/libavcodec/allcodecs.c
> @@ -289,6 +289,7 @@ extern AVCodec ff_s302m_decoder;
>   extern AVCodec ff_sanm_decoder;
>   extern AVCodec ff_scpr_decoder;
>   extern AVCodec ff_screenpresso_decoder;
> +extern AVCodec ff_sga_decoder;
>   extern AVCodec ff_sgi_encoder;
>   extern AVCodec ff_sgi_decoder;
>   extern AVCodec ff_sgirle_decoder;
> diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
> index f64ba488f2..17f8a14044 100644
> --- a/libavcodec/codec_desc.c
> +++ b/libavcodec/codec_desc.c
> @@ -1849,6 +1849,13 @@ static const AVCodecDescriptor codec_descriptors[] = {
>           .long_name = NULL_IF_CONFIG_SMALL("Simbiosis Interactive IMX Video"),
>           .props     = AV_CODEC_PROP_LOSSY,
>       },
> +    {
> +        .id        = AV_CODEC_ID_SGA_VIDEO,
> +        .type      = AVMEDIA_TYPE_VIDEO,
> +        .name      = "sga",
> +        .long_name = NULL_IF_CONFIG_SMALL("Digital Pictures SGA Video"),
> +        .props     = AV_CODEC_PROP_LOSSY,
> +    },
>   
>       /* various PCM "codecs" */
>       {
> diff --git a/libavcodec/codec_id.h b/libavcodec/codec_id.h
> index 7dd316afd2..ab7bc68ee2 100644
> --- a/libavcodec/codec_id.h
> +++ b/libavcodec/codec_id.h
> @@ -306,6 +306,7 @@ enum AVCodecID {
>       AV_CODEC_ID_ARGO,
>       AV_CODEC_ID_CRI,
>       AV_CODEC_ID_SIMBIOSIS_IMX,
> +    AV_CODEC_ID_SGA_VIDEO,
>   
>       /* various PCM "codecs" */
>       AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs
> diff --git a/libavcodec/sga.c b/libavcodec/sga.c
> new file mode 100644
> index 0000000000..00752a5843
> --- /dev/null
> +++ b/libavcodec/sga.c

sgadec.c?

[...]

> +    memcpy(frame->data[1], s->pal, AVPALETTE_SIZE);
> +    frame->palette_has_changed = 1;
> +    frame->pict_type = AV_PICTURE_TYPE_I;

Missing intra only in codec_desc.c, then?

> +    frame->key_frame = 1;

The demuxer does not seem to set every packet as key frame, only some. 
Which is it?

> +
> +    *got_frame = 1;
> +
> +    return avpkt->size;
> +}
> +
> +static av_cold int sga_decode_end(AVCodecContext *avctx)
> +{
> +    SGAVideoContext *s = avctx->priv_data;
> +
> +    av_freep(&s->tileindex_data);
> +    s->tileindex_size = 0;
> +
> +    av_freep(&s->palmapindex_data);
> +    s->palmapindex_size = 0;
> +
> +    return 0;
> +}
> +
> +AVCodec ff_sga_decoder = {
> +    .name           = "sga",
> +    .long_name      = NULL_IF_CONFIG_SMALL("Digital Pictures SGA Video"),
> +    .type           = AVMEDIA_TYPE_VIDEO,
> +    .id             = AV_CODEC_ID_SGA_VIDEO,
> +    .priv_data_size = sizeof(SGAVideoContext),
> +    .init           = sga_decode_init,
> +    .decode         = sga_decode_frame,
> +    .close          = sga_decode_end,
> +    .capabilities   = AV_CODEC_CAP_DR1,
> +    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
> +};
>
Carl Eugen Hoyos Feb. 27, 2021, 9:27 a.m. UTC | #2
Am Fr., 26. Feb. 2021 um 12:55 Uhr schrieb Paul B Mahol <onemda@gmail.com>:

> +static int decode_palette(GetByteContext *gb, uint32_t *pal)
> +{
> +    GetBitContext gbit;
> +
> +    if (bytestream2_get_bytes_left(gb) < 18)
> +        return AVERROR_INVALIDDATA;
> +
> +    memset(pal, 0, 16 * sizeof(*pal));
> +    init_get_bits8(&gbit, gb->buffer, 18);
> +
> +    for (int RGBIndex = 0; RGBIndex < 3; RGBIndex++) {
> +        for (int index = 0; index < 16; index++) {
> +            unsigned color = get_bits1(&gbit) << RGBIndex;
> +            pal[15 - index] |= color << (5 + 16);
> +        }
> +    }
> +
> +    for (int RGBIndex = 0; RGBIndex < 3; RGBIndex++) {
> +        for (int index = 0; index < 16; index++) {
> +            unsigned color = get_bits1(&gbit) << RGBIndex;
> +            pal[15 - index] |= color << (5 + 8);
> +        }
> +    }
> +
> +    for (int RGBIndex = 0; RGBIndex < 3; RGBIndex++) {
> +        for (int index = 0; index < 16; index++) {
> +            unsigned color = get_bits1(&gbit) << RGBIndex;
> +            pal[15 - index] |= color << (5 + 0);
> +        }
> +    }
> +
> +    for (int index = 0; index < 16; index++)
> +        pal[index] = (0xFFU << 24) | pal[index] | (pal[index] >> 3);

Looks much better than what I suggested but please
also fill the last two bits of each component.

Carl Eugen
Paul B Mahol Feb. 27, 2021, 12:18 p.m. UTC | #3
On Sat, Feb 27, 2021 at 4:19 AM James Almer <jamrial@gmail.com> wrote:

> On 2/26/2021 8:29 AM, Paul B Mahol wrote:
> > Signed-off-by: Paul B Mahol <onemda@gmail.com>
> > ---
> >   libavcodec/Makefile     |   1 +
> >   libavcodec/allcodecs.c  |   1 +
> >   libavcodec/codec_desc.c |   7 +
> >   libavcodec/codec_id.h   |   1 +
> >   libavcodec/sga.c        | 534 ++++++++++++++++++++++++++++++++++++++++
> >   5 files changed, 544 insertions(+)
> >   create mode 100644 libavcodec/sga.c
> >
> > diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> > index fe7026c1db..850657ae3c 100644
> > --- a/libavcodec/Makefile
> > +++ b/libavcodec/Makefile
> > @@ -609,6 +609,7 @@ OBJS-$(CONFIG_SANM_DECODER)            += sanm.o
> >   OBJS-$(CONFIG_SCPR_DECODER)            += scpr.o
> >   OBJS-$(CONFIG_SCREENPRESSO_DECODER)    += screenpresso.o
> >   OBJS-$(CONFIG_SDX2_DPCM_DECODER)       += dpcm.o
> > +OBJS-$(CONFIG_SGA_DECODER)             += sga.o
> >   OBJS-$(CONFIG_SGI_DECODER)             += sgidec.o
> >   OBJS-$(CONFIG_SGI_ENCODER)             += sgienc.o rle.o
> >   OBJS-$(CONFIG_SGIRLE_DECODER)          += sgirledec.o
> > diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
> > index 990998b64b..a04faead16 100644
> > --- a/libavcodec/allcodecs.c
> > +++ b/libavcodec/allcodecs.c
> > @@ -289,6 +289,7 @@ extern AVCodec ff_s302m_decoder;
> >   extern AVCodec ff_sanm_decoder;
> >   extern AVCodec ff_scpr_decoder;
> >   extern AVCodec ff_screenpresso_decoder;
> > +extern AVCodec ff_sga_decoder;
> >   extern AVCodec ff_sgi_encoder;
> >   extern AVCodec ff_sgi_decoder;
> >   extern AVCodec ff_sgirle_decoder;
> > diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
> > index f64ba488f2..17f8a14044 100644
> > --- a/libavcodec/codec_desc.c
> > +++ b/libavcodec/codec_desc.c
> > @@ -1849,6 +1849,13 @@ static const AVCodecDescriptor
> codec_descriptors[] = {
> >           .long_name = NULL_IF_CONFIG_SMALL("Simbiosis Interactive IMX
> Video"),
> >           .props     = AV_CODEC_PROP_LOSSY,
> >       },
> > +    {
> > +        .id        = AV_CODEC_ID_SGA_VIDEO,
> > +        .type      = AVMEDIA_TYPE_VIDEO,
> > +        .name      = "sga",
> > +        .long_name = NULL_IF_CONFIG_SMALL("Digital Pictures SGA Video"),
> > +        .props     = AV_CODEC_PROP_LOSSY,
> > +    },
> >
> >       /* various PCM "codecs" */
> >       {
> > diff --git a/libavcodec/codec_id.h b/libavcodec/codec_id.h
> > index 7dd316afd2..ab7bc68ee2 100644
> > --- a/libavcodec/codec_id.h
> > +++ b/libavcodec/codec_id.h
> > @@ -306,6 +306,7 @@ enum AVCodecID {
> >       AV_CODEC_ID_ARGO,
> >       AV_CODEC_ID_CRI,
> >       AV_CODEC_ID_SIMBIOSIS_IMX,
> > +    AV_CODEC_ID_SGA_VIDEO,
> >
> >       /* various PCM "codecs" */
> >       AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at
> the start of audio codecs
> > diff --git a/libavcodec/sga.c b/libavcodec/sga.c
> > new file mode 100644
> > index 0000000000..00752a5843
> > --- /dev/null
> > +++ b/libavcodec/sga.c
>
> sgadec.c?
>

Nope.


>
> [...]
>
> > +    memcpy(frame->data[1], s->pal, AVPALETTE_SIZE);
> > +    frame->palette_has_changed = 1;
> > +    frame->pict_type = AV_PICTURE_TYPE_I;
>
> Missing intra only in codec_desc.c, then?
>

Nope, codec have support for inter frames, just not implemented yet.

>
> > +    frame->key_frame = 1;
>
> The demuxer does not seem to set every packet as key frame, only some.


That is for working seeking, if you have not noticed there are not pure
chunks but chunks muxed
in sectors of 2048 bytes.



>
> Which is it?
>
> > +
> > +    *got_frame = 1;
> > +
> > +    return avpkt->size;
> > +}
> > +
> > +static av_cold int sga_decode_end(AVCodecContext *avctx)
> > +{
> > +    SGAVideoContext *s = avctx->priv_data;
> > +
> > +    av_freep(&s->tileindex_data);
> > +    s->tileindex_size = 0;
> > +
> > +    av_freep(&s->palmapindex_data);
> > +    s->palmapindex_size = 0;
> > +
> > +    return 0;
> > +}
> > +
> > +AVCodec ff_sga_decoder = {
> > +    .name           = "sga",
> > +    .long_name      = NULL_IF_CONFIG_SMALL("Digital Pictures SGA
> Video"),
> > +    .type           = AVMEDIA_TYPE_VIDEO,
> > +    .id             = AV_CODEC_ID_SGA_VIDEO,
> > +    .priv_data_size = sizeof(SGAVideoContext),
> > +    .init           = sga_decode_init,
> > +    .decode         = sga_decode_frame,
> > +    .close          = sga_decode_end,
> > +    .capabilities   = AV_CODEC_CAP_DR1,
> > +    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
> > +};
> >
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
diff mbox series

Patch

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index fe7026c1db..850657ae3c 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -609,6 +609,7 @@  OBJS-$(CONFIG_SANM_DECODER)            += sanm.o
 OBJS-$(CONFIG_SCPR_DECODER)            += scpr.o
 OBJS-$(CONFIG_SCREENPRESSO_DECODER)    += screenpresso.o
 OBJS-$(CONFIG_SDX2_DPCM_DECODER)       += dpcm.o
+OBJS-$(CONFIG_SGA_DECODER)             += sga.o
 OBJS-$(CONFIG_SGI_DECODER)             += sgidec.o
 OBJS-$(CONFIG_SGI_ENCODER)             += sgienc.o rle.o
 OBJS-$(CONFIG_SGIRLE_DECODER)          += sgirledec.o
diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
index 990998b64b..a04faead16 100644
--- a/libavcodec/allcodecs.c
+++ b/libavcodec/allcodecs.c
@@ -289,6 +289,7 @@  extern AVCodec ff_s302m_decoder;
 extern AVCodec ff_sanm_decoder;
 extern AVCodec ff_scpr_decoder;
 extern AVCodec ff_screenpresso_decoder;
+extern AVCodec ff_sga_decoder;
 extern AVCodec ff_sgi_encoder;
 extern AVCodec ff_sgi_decoder;
 extern AVCodec ff_sgirle_decoder;
diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
index f64ba488f2..17f8a14044 100644
--- a/libavcodec/codec_desc.c
+++ b/libavcodec/codec_desc.c
@@ -1849,6 +1849,13 @@  static const AVCodecDescriptor codec_descriptors[] = {
         .long_name = NULL_IF_CONFIG_SMALL("Simbiosis Interactive IMX Video"),
         .props     = AV_CODEC_PROP_LOSSY,
     },
+    {
+        .id        = AV_CODEC_ID_SGA_VIDEO,
+        .type      = AVMEDIA_TYPE_VIDEO,
+        .name      = "sga",
+        .long_name = NULL_IF_CONFIG_SMALL("Digital Pictures SGA Video"),
+        .props     = AV_CODEC_PROP_LOSSY,
+    },
 
     /* various PCM "codecs" */
     {
diff --git a/libavcodec/codec_id.h b/libavcodec/codec_id.h
index 7dd316afd2..ab7bc68ee2 100644
--- a/libavcodec/codec_id.h
+++ b/libavcodec/codec_id.h
@@ -306,6 +306,7 @@  enum AVCodecID {
     AV_CODEC_ID_ARGO,
     AV_CODEC_ID_CRI,
     AV_CODEC_ID_SIMBIOSIS_IMX,
+    AV_CODEC_ID_SGA_VIDEO,
 
     /* various PCM "codecs" */
     AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs
diff --git a/libavcodec/sga.c b/libavcodec/sga.c
new file mode 100644
index 0000000000..00752a5843
--- /dev/null
+++ b/libavcodec/sga.c
@@ -0,0 +1,534 @@ 
+/*
+ * Copyright (c) 2021 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 "libavutil/avassert.h"
+#include "libavutil/common.h"
+#include "avcodec.h"
+#include "get_bits.h"
+#include "bytestream.h"
+#include "internal.h"
+
+#define PALDATA_FOLLOWS_TILEDATA 4
+#define HAVE_COMPRESSED_TILEMAP 32
+#define HAVE_TILEMAP 128
+
+typedef struct SGAVideoContext {
+    GetByteContext gb;
+
+    int metadata_size;
+    int tiledata_size;
+    int tiledata_offset;
+    int tilemapdata_size;
+    int tilemapdata_offset;
+    int paldata_size;
+    int paldata_offset;
+    int palmapdata_offset;
+    int palmapdata_size;
+
+    int flags;
+    int nb_pal;
+    int nb_tiles;
+    int tiles_w, tiles_h;
+    int shift;
+    int plus;
+    int swap;
+
+    uint32_t pal[256];
+    uint8_t *tileindex_data;
+    unsigned tileindex_size;
+    uint8_t *palmapindex_data;
+    unsigned palmapindex_size;
+    uint8_t uncompressed[65536];
+} SGAVideoContext;
+
+static av_cold int sga_decode_init(AVCodecContext *avctx)
+{
+    avctx->pix_fmt = AV_PIX_FMT_PAL8;
+    return 0;
+}
+
+static int decode_palette(GetByteContext *gb, uint32_t *pal)
+{
+    GetBitContext gbit;
+
+    if (bytestream2_get_bytes_left(gb) < 18)
+        return AVERROR_INVALIDDATA;
+
+    memset(pal, 0, 16 * sizeof(*pal));
+    init_get_bits8(&gbit, gb->buffer, 18);
+
+    for (int RGBIndex = 0; RGBIndex < 3; RGBIndex++) {
+        for (int index = 0; index < 16; index++) {
+            unsigned color = get_bits1(&gbit) << RGBIndex;
+            pal[15 - index] |= color << (5 + 16);
+        }
+    }
+
+    for (int RGBIndex = 0; RGBIndex < 3; RGBIndex++) {
+        for (int index = 0; index < 16; index++) {
+            unsigned color = get_bits1(&gbit) << RGBIndex;
+            pal[15 - index] |= color << (5 + 8);
+        }
+    }
+
+    for (int RGBIndex = 0; RGBIndex < 3; RGBIndex++) {
+        for (int index = 0; index < 16; index++) {
+            unsigned color = get_bits1(&gbit) << RGBIndex;
+            pal[15 - index] |= color << (5 + 0);
+        }
+    }
+
+    for (int index = 0; index < 16; index++)
+        pal[index] = (0xFFU << 24) | pal[index] | (pal[index] >> 3);
+
+    bytestream2_skip(gb, 18);
+
+    return 0;
+}
+
+static int decode_index_palmap(SGAVideoContext *s, AVFrame *frame)
+{
+    const uint8_t *tt = s->tileindex_data;
+
+    for (int y = 0; y < s->tiles_h; y++) {
+        for (int x = 0; x < s->tiles_w; x++) {
+            int pal_idx = s->palmapindex_data[y * s->tiles_w + x] * 16;
+            uint8_t *dst = frame->data[0] + y * 8 * frame->linesize[0] + x * 8;
+
+            for (int yy = 0; yy < 8; yy++) {
+                for (int xx = 0; xx < 8; xx++)
+                    dst[xx] = pal_idx + tt[xx];
+                tt += 8;
+
+                dst += frame->linesize[0];
+            }
+        }
+    }
+
+    return 0;
+}
+
+static int decode_index_tilemap(SGAVideoContext *s, AVFrame *frame)
+{
+    GetByteContext *gb = &s->gb;
+    GetBitContext pm;
+
+    bytestream2_seek(gb, s->tilemapdata_offset, SEEK_SET);
+    if (bytestream2_get_bytes_left(gb) < s->tilemapdata_size)
+        return AVERROR_INVALIDDATA;
+
+    init_get_bits8(&pm, gb->buffer, s->tilemapdata_size);
+
+    for (int y = 0; y < s->tiles_h; y++) {
+        for (int x = 0; x < s->tiles_w; x++) {
+            uint8_t tile[64];
+            int tilemap = get_bits(&pm, 16);
+            int flip_x = (tilemap >> 11) & 1;
+            int flip_y = (tilemap >> 12) & 1;
+            int tindex = av_clip((tilemap & 511) - 1, 0, s->nb_tiles - 1);
+            const uint8_t *tt = s->tileindex_data + tindex * 64;
+            int pal_idx = ((tilemap >> 13) & 3) * 16;
+            uint8_t *dst = frame->data[0] + y * 8 * frame->linesize[0] + x * 8;
+
+            if (!flip_x && !flip_y) {
+                memcpy(tile, tt, 64);
+            } else if (flip_x && flip_y) {
+                for (int i = 0; i < 8; i++) {
+                    for (int j = 0; j < 8; j++)
+                        tile[i * 8 + j] = tt[(7 - i) * 8 + 7 - j];
+                }
+            } else if (flip_x) {
+                for (int i = 0; i < 8; i++) {
+                    for (int j = 0; j < 8; j++)
+                        tile[i * 8 + j] = tt[i * 8 + 7 - j];
+                }
+            } else {
+                for (int i = 0; i < 8; i++) {
+                    for (int j = 0; j < 8; j++)
+                        tile[i * 8 + j] = tt[(7 - i) * 8 + j];
+                }
+            }
+
+            for (int yy = 0; yy < 8; yy++) {
+                for (int xx = 0; xx < 8; xx++)
+                    dst[xx] = pal_idx + tile[xx + yy * 8];
+
+                dst += frame->linesize[0];
+            }
+        }
+    }
+
+    return 0;
+}
+
+static int decode_index(SGAVideoContext *s, AVFrame *frame)
+{
+    const uint8_t *src = s->tileindex_data;
+    uint8_t *dst = frame->data[0];
+
+    for (int y = 0; y < frame->height; y += 8) {
+        for (int x = 0; x < frame->width; x += 8) {
+            for (int yy = 0; yy < 8; yy++) {
+                for (int xx = 0; xx < 8; xx++)
+                    dst[x + xx + yy * frame->linesize[0]] = src[xx];
+                src += 8;
+            }
+        }
+
+        dst += 8 * frame->linesize[0];
+    }
+
+    return 0;
+}
+
+static int lzss_decompress(AVCodecContext *avctx,
+                           GetByteContext *gb, uint8_t *dst,
+                           int dst_size, int shift, int plus)
+{
+    int oi = 0;
+
+    while (bytestream2_get_bytes_left(gb) > 0 && oi < dst_size) {
+        uint16_t displace, header = bytestream2_get_be16(gb);
+        int count, offset;
+
+        for (int i = 0; i < 16; i++) {
+            switch (header >> 15) {
+            case 0:
+                if (oi + 2 < dst_size) {
+                    dst[oi++] = bytestream2_get_byte(gb);
+                    dst[oi++] = bytestream2_get_byte(gb);
+                }
+                break;
+            case 1:
+                displace = bytestream2_get_be16(gb);
+                count = displace >> shift;
+                offset = displace & ((1 << shift) - 1);
+
+                if (displace == 0) {
+                    while (bytestream2_get_bytes_left(gb) > 0 &&
+                           oi < dst_size)
+                        dst[oi++] = bytestream2_get_byte(gb);
+                    return oi;
+                }
+
+                count += plus;
+
+                if (offset <= 0)
+                    offset = 1;
+                if (oi < offset)
+                    return AVERROR_INVALIDDATA;
+                for (int j = 0; j < count * 2; j++) {
+                    dst[oi] = dst[oi - offset];
+                    oi++;
+                }
+                break;
+            }
+
+            header <<= 1;
+        }
+    }
+
+    return AVERROR_INVALIDDATA;
+}
+
+static int decode_palmapdata(AVCodecContext *avctx)
+{
+    SGAVideoContext *s = avctx->priv_data;
+    const int bits = (s->nb_pal + 1) / 2;
+    GetByteContext *gb = &s->gb;
+    GetBitContext pm;
+
+    bytestream2_seek(gb, s->palmapdata_offset, SEEK_SET);
+    if (bytestream2_get_bytes_left(gb) < s->palmapdata_size)
+        return AVERROR_INVALIDDATA;
+    init_get_bits8(&pm, gb->buffer, s->palmapdata_size);
+
+    for (int y = 0; y < s->tiles_h; y++) {
+        uint8_t *dst = s->palmapindex_data + y * s->tiles_w;
+
+        for (int x = 0; x < s->tiles_w; x++)
+            dst[x] = get_bits(&pm, bits);
+
+        dst += s->tiles_w;
+    }
+
+    return 0;
+}
+
+static int decode_tiledata(AVCodecContext *avctx)
+{
+    SGAVideoContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    GetBitContext tm;
+
+    bytestream2_seek(gb, s->tiledata_offset, SEEK_SET);
+    if (bytestream2_get_bytes_left(gb) < s->tiledata_size)
+        return AVERROR_INVALIDDATA;
+    init_get_bits8(&tm, gb->buffer, s->tiledata_size);
+
+    for (int n = 0; n < s->nb_tiles; n++) {
+        uint8_t *dst = s->tileindex_data + n * 64;
+
+        for (int yy = 0; yy < 8; yy++) {
+            for (int xx = 0; xx < 8; xx++)
+                dst[xx] = get_bits(&tm, 4);
+
+            dst += 8;
+        }
+    }
+
+    for (int i = 0; i < s->nb_tiles && s->swap; i++) {
+        uint8_t *dst = s->tileindex_data + i * 64;
+
+        for (int j = 8; j < 64; j += 16) {
+            for (int k = 0; k < 8; k += 2)
+                FFSWAP(uint8_t, dst[j + k], dst[j+k+1]);
+        }
+    }
+
+    return 0;
+}
+
+static int sga_decode_frame(AVCodecContext *avctx, void *data,
+                            int *got_frame, AVPacket *avpkt)
+{
+    SGAVideoContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    AVFrame *frame = data;
+    int ret, type;
+
+    if (avpkt->size <= 14)
+        return AVERROR_INVALIDDATA;
+
+    s->flags  = avpkt->data[8];
+    s->nb_pal = avpkt->data[9];
+    s->tiles_w = avpkt->data[10];
+    s->tiles_h = avpkt->data[11];
+
+    if (s->nb_pal > 4)
+        return AVERROR_INVALIDDATA;
+
+    if ((ret = ff_set_dimensions(avctx,
+                                 s->tiles_w * 8,
+                                 s->tiles_h * 8)) < 0)
+        return ret;
+
+    av_fast_padded_malloc(&s->tileindex_data, &s->tileindex_size,
+                          avctx->width * avctx->height);
+    if (!s->tileindex_data)
+        return AVERROR(ENOMEM);
+
+    av_fast_padded_malloc(&s->palmapindex_data, &s->palmapindex_size,
+                          s->tiles_w * s->tiles_h);
+    if (!s->palmapindex_data)
+        return AVERROR(ENOMEM);
+
+    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
+        return ret;
+
+    bytestream2_init(gb, avpkt->data, avpkt->size);
+
+    type = bytestream2_get_byte(gb);
+    s->metadata_size = 12 + ((!!(s->flags & HAVE_TILEMAP)) * 2);
+    s->nb_tiles = s->flags & HAVE_TILEMAP ? AV_RB16(avpkt->data + 12) : s->tiles_w * s->tiles_h;
+    if (s->nb_tiles > s->tiles_w * s->tiles_h)
+        return AVERROR_INVALIDDATA;
+
+    av_log(avctx, AV_LOG_DEBUG, "type: %X flags: %X nb_tiles: %d\n", type, s->flags, s->nb_tiles);
+
+    switch (type) {
+    case 0xE7:
+    case 0xCB:
+    case 0xCD:
+        s->swap = 1;
+        s->shift = 12;
+        s->plus = 1;
+        break;
+    case 0xC9:
+        s->swap = 1;
+        s->shift = 13;
+        s->plus = 1;
+        break;
+    case 0xC8:
+        s->swap = 1;
+        s->shift = 13;
+        s->plus = 0;
+        break;
+    case 0xC7:
+        s->swap = 0;
+        s->shift = 13;
+        s->plus = 1;
+        break;
+    case 0xC6:
+        s->swap = 0;
+        s->shift = 13;
+        s->plus = 0;
+        break;
+    }
+
+    if (type == 0xE7) {
+        int offset = s->metadata_size, left;
+        int sizes[3];
+
+        bytestream2_seek(gb, s->metadata_size, SEEK_SET);
+
+        for (int i = 0; i < 3; i++)
+            sizes[i] = bytestream2_get_be16(gb);
+
+        for (int i = 0; i < 3; i++) {
+            int size = sizes[i];
+            int raw = size >> 15;
+
+            size &= (1 << 15) - 1;
+
+            if (raw) {
+                if (bytestream2_get_bytes_left(gb) < size)
+                    return AVERROR_INVALIDDATA;
+
+                if (sizeof(s->uncompressed) - offset < size)
+                    return AVERROR_INVALIDDATA;
+
+                memcpy(s->uncompressed + offset, gb->buffer, size);
+                bytestream2_skip(gb, size);
+            } else {
+                GetByteContext gb2;
+
+                if (bytestream2_get_bytes_left(gb) < size)
+                    return AVERROR_INVALIDDATA;
+
+                bytestream2_init(&gb2, gb->buffer, size);
+                ret = lzss_decompress(avctx, &gb2, s->uncompressed + offset,
+                                      sizeof(s->uncompressed) - offset, s->shift, s->plus);
+                if (ret < 0)
+                    return ret;
+                bytestream2_skip(gb, size);
+                size = ret;
+            }
+
+            offset += size;
+        }
+
+        left = bytestream2_get_bytes_left(gb);
+        if (sizeof(s->uncompressed) - offset < left)
+            return AVERROR_INVALIDDATA;
+
+        bytestream2_get_buffer(gb, s->uncompressed + offset, left);
+
+        offset += left;
+        bytestream2_init(gb, s->uncompressed, offset);
+    }
+
+    switch (type) {
+    case 0xCD:
+    case 0xCB:
+    case 0xC9:
+    case 0xC8:
+    case 0xC7:
+    case 0xC6:
+        bytestream2_seek(gb, s->metadata_size, SEEK_SET);
+        ret = lzss_decompress(avctx, gb, s->uncompressed + s->metadata_size,
+                              sizeof(s->uncompressed) - s->metadata_size, s->shift, s->plus);
+        if (ret < 0)
+            return ret;
+        bytestream2_init(gb, s->uncompressed, ret + s->metadata_size);
+    case 0xE7:
+    case 0xC1:
+        s->tiledata_size = s->nb_tiles * 32;
+        s->paldata_size = s->nb_pal * 18;
+        s->tiledata_offset = s->flags & PALDATA_FOLLOWS_TILEDATA ? s->metadata_size : s->metadata_size + s->paldata_size;
+        s->paldata_offset = s->flags & PALDATA_FOLLOWS_TILEDATA ? s->metadata_size + s->tiledata_size : s->metadata_size;
+        s->palmapdata_offset = (s->flags & HAVE_TILEMAP) ? -1 : s->paldata_offset + s->paldata_size;
+        s->palmapdata_size = (s->flags & HAVE_TILEMAP) || s->nb_pal < 2 ? 0 : (s->tiles_w * s->tiles_h * ((s->nb_pal + 1) / 2) + 7) / 8;
+        s->tilemapdata_size = (s->flags & HAVE_TILEMAP) ? s->tiles_w * s->tiles_h * 2 : 0;
+        s->tilemapdata_offset = (s->flags & HAVE_TILEMAP) ? s->paldata_offset + s->paldata_size: -1;
+
+        bytestream2_seek(gb, s->paldata_offset, SEEK_SET);
+        for (int n = 0; n < s->nb_pal; n++) {
+            ret = decode_palette(gb, s->pal + 16 * n);
+            if (ret < 0)
+                return ret;
+        }
+
+        if (s->tiledata_size > 0) {
+            ret = decode_tiledata(avctx);
+            if (ret < 0)
+                return ret;
+        }
+
+        if (s->palmapdata_size > 0) {
+            ret = decode_palmapdata(avctx);
+            if (ret < 0)
+                return ret;
+        }
+
+        if (s->palmapdata_size > 0 && s->tiledata_size > 0) {
+            ret = decode_index_palmap(s, frame);
+            if (ret < 0)
+                return ret;
+        } else if (s->tilemapdata_size > 0 && s->tiledata_size > 0) {
+            ret = decode_index_tilemap(s, frame);
+            if (ret < 0)
+                return ret;
+        } else if (s->tiledata_size > 0) {
+            ret = decode_index(s, frame);
+            if (ret < 0)
+                return ret;
+        }
+        break;
+    default:
+        av_log(avctx, AV_LOG_ERROR, "Unknown type: %X\n", type);
+        return AVERROR_INVALIDDATA;
+    }
+
+    memcpy(frame->data[1], s->pal, AVPALETTE_SIZE);
+    frame->palette_has_changed = 1;
+    frame->pict_type = AV_PICTURE_TYPE_I;
+    frame->key_frame = 1;
+
+    *got_frame = 1;
+
+    return avpkt->size;
+}
+
+static av_cold int sga_decode_end(AVCodecContext *avctx)
+{
+    SGAVideoContext *s = avctx->priv_data;
+
+    av_freep(&s->tileindex_data);
+    s->tileindex_size = 0;
+
+    av_freep(&s->palmapindex_data);
+    s->palmapindex_size = 0;
+
+    return 0;
+}
+
+AVCodec ff_sga_decoder = {
+    .name           = "sga",
+    .long_name      = NULL_IF_CONFIG_SMALL("Digital Pictures SGA Video"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_SGA_VIDEO,
+    .priv_data_size = sizeof(SGAVideoContext),
+    .init           = sga_decode_init,
+    .decode         = sga_decode_frame,
+    .close          = sga_decode_end,
+    .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
+};