diff mbox series

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

Message ID 20210223172509.29631-2-onemda@gmail.com
State Superseded
Headers show
Series [FFmpeg-devel,1/3] avcodec: add SGA PCM decoder
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Commit Message

Paul B Mahol Feb. 23, 2021, 5:25 p.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        | 525 ++++++++++++++++++++++++++++++++++++++++
 5 files changed, 535 insertions(+)
 create mode 100644 libavcodec/sga.c

Comments

James Almer Feb. 23, 2021, 5:49 p.m. UTC | #1
On 2/23/2021 2:25 PM, 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        | 525 ++++++++++++++++++++++++++++++++++++++++
>   5 files changed, 535 insertions(+)
>   create mode 100644 libavcodec/sga.c
> 
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 8685c15eeb..dfb4a89c92 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,

AV_CODEC_PROP_INTRA_ONLY? Judging by how the demuxer sets every packet 
as a key frame.

[...]

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

Missing frame->key_frame and frame->pict_type.

> +
> +    *got_frame = 1;
> +
> +    return avpkt->size;
> +}
Carl Eugen Hoyos Feb. 23, 2021, 6:50 p.m. UTC | #2
Am Di., 23. Feb. 2021 um 18:32 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);
> +        }
> +    }

This will not allow white to look white on the screen,
you have to add color more often to pal.

Carl Eugen
Paul B Mahol Feb. 23, 2021, 7:27 p.m. UTC | #3
On Tue, Feb 23, 2021 at 8:20 PM Carl Eugen Hoyos <ceffmpeg@gmail.com> wrote:

> Am Di., 23. Feb. 2021 um 18:32 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);
> > +        }
> > +    }
>
> This will not allow white to look white on the screen,
> you have to add color more often to pal.
>
>
What this even means?


> Carl Eugen
> _______________________________________________
> 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".
Carl Eugen Hoyos Feb. 23, 2021, 7:39 p.m. UTC | #4
Am Di., 23. Feb. 2021 um 20:27 Uhr schrieb Paul B Mahol <onemda@gmail.com>:
>
> On Tue, Feb 23, 2021 at 8:20 PM Carl Eugen Hoyos <ceffmpeg@gmail.com> wrote:
>
> > Am Di., 23. Feb. 2021 um 18:32 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);
> > > +        }
> > > +    }
> >
> > This will not allow white to look white on the screen,
> > you have to add color more often to pal.
> >
> >
> What this even means?

The value closest to white that is possible with above
code (please correct me if I am wrong) is:
0xE0E0E0
This is visually different than 0xFFFFFF

Something like the following is possible, simpler solutions
probably exist:
pal{15-index] |= color << 16+5 | color << 16+2 | (color & 6) << 16-1 ;

pal[15-index] |= color << 8+5 | color << 8+2 | (color & 6) << 8-1;

pal[15-index] |= color << 5 | color << 2 | color >> 1;


Carl Eugen
diff mbox series

Patch

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 8685c15eeb..dfb4a89c92 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..56e8fc9032
--- /dev/null
+++ b/libavcodec/sga.c
@@ -0,0 +1,525 @@ 
+/*
+ * 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;
+
+    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 = FFMAX((tilemap & 511) - 1, 0);
+            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;
+    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, 2);
+
+        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 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 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;
+
+    *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,
+};