avcodec: add RemotelyAnywhere Screen Capture decoder

1 files changed, 812 insertions, 0 deletions

diff --git a/libavcodec/rasc.c b/libavcodec/rasc.c
new file mode 100644
index 0000000000..fbbb134f4b
--- /dev/null
+++ b/libavcodec/rasc.c
@@ -0,0 +1,812 @@
+/*
+ * RemotelyAnywhere Screen Capture 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 "libavutil/avassert.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
+
+#include "avcodec.h"
+#include "bytestream.h"
+#include "internal.h"
+
+#include <zlib.h>
+
+#define KBND MKTAG('K', 'B', 'N', 'D')
+#define FINT MKTAG('F', 'I', 'N', 'T')
+#define INIT MKTAG('I', 'N', 'I', 'T')
+#define BNDL MKTAG('B', 'N', 'D', 'L')
+#define KFRM MKTAG('K', 'F', 'R', 'M')
+#define DLTA MKTAG('D', 'L', 'T', 'A')
+#define MOUS MKTAG('M', 'O', 'U', 'S')
+#define MPOS MKTAG('M', 'P', 'O', 'S')
+#define MOVE MKTAG('M', 'O', 'V', 'E')
+#define EMPT MKTAG('E', 'M', 'P', 'T')
+
+typedef struct RASCContext {
+    AVClass        *class;
+    int             skip_cursor;
+    GetByteContext  gb;
+    uint8_t        *delta;
+    int             delta_size;
+    uint8_t        *cursor;
+    int             cursor_size;
+    unsigned        cursor_w;
+    unsigned        cursor_h;
+    unsigned        cursor_x;
+    unsigned        cursor_y;
+    int             stride;
+    int             bpp;
+    z_stream        zstream;
+    AVFrame        *frame;
+    AVFrame        *frame1;
+    AVFrame        *frame2;
+} RASCContext;
+
+static void clear_plane(AVCodecContext *avctx, AVFrame *frame)
+{
+    RASCContext *s = avctx->priv_data;
+    uint8_t *dst = frame->data[0];
+
+    for (int y = 0; y < avctx->height; y++) {
+        memset(dst, 0, avctx->width * s->bpp);
+        dst += frame->linesize[0];
+    }
+}
+
+static void copy_plane(AVCodecContext *avctx, AVFrame *src, AVFrame *dst)
+{
+    RASCContext *s = avctx->priv_data;
+    uint8_t *srcp = src->data[0];
+    uint8_t *dstp = dst->data[0];
+
+    for (int y = 0; y < avctx->height; y++) {
+        memcpy(dstp, srcp, s->stride);
+        srcp += src->linesize[0];
+        dstp += dst->linesize[0];
+    }
+}
+
+static int init_frames(AVCodecContext *avctx)
+{
+    RASCContext *s = avctx->priv_data;
+    int ret;
+
+    av_frame_unref(s->frame1);
+    if ((ret = ff_get_buffer(avctx, s->frame1, 0)) < 0)
+        return ret;
+
+    av_frame_unref(s->frame2);
+    if ((ret = ff_get_buffer(avctx, s->frame2, 0)) < 0)
+        return ret;
+
+    clear_plane(avctx, s->frame2);
+    clear_plane(avctx, s->frame1);
+
+    return 0;
+}
+
+static int decode_fint(AVCodecContext *avctx,
+                       AVPacket *avpkt, unsigned size)
+{
+    RASCContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    unsigned w, h, fmt;
+    int ret;
+
+    if (bytestream2_peek_le32(gb) != 0x65) {
+        if (!s->frame2->data[0] || !s->frame1->data[0])
+            return AVERROR_INVALIDDATA;
+
+        clear_plane(avctx, s->frame2);
+        clear_plane(avctx, s->frame1);
+        return 0;
+    }
+
+    bytestream2_skip(gb, 8);
+    w = bytestream2_get_le32(gb);
+    h = bytestream2_get_le32(gb);
+    bytestream2_skip(gb, 30);
+    fmt = bytestream2_get_le16(gb);
+    bytestream2_skip(gb, 24);
+
+    switch (fmt) {
+    case 8:  s->stride = FFALIGN(w, 4);
+             s->bpp    = 1;
+             fmt = AV_PIX_FMT_PAL8; break;
+    case 16: s->stride = w * 2;
+             s->bpp    = 2;
+             fmt = AV_PIX_FMT_RGB555LE; break;
+    case 32: s->stride = w * 4;
+             s->bpp    = 4;
+             fmt = AV_PIX_FMT_BGR0; break;
+    default: return AVERROR_INVALIDDATA;
+    }
+
+    ret = ff_set_dimensions(avctx, w, h);
+    if (ret < 0)
+        return ret;
+    avctx->width  = w;
+    avctx->height = h;
+    avctx->pix_fmt = fmt;
+
+    ret = init_frames(avctx);
+    if (ret < 0)
+        return ret;
+
+    if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
+        uint32_t *pal = (uint32_t *)s->frame2->data[1];
+
+        for (int i = 0; i < 256; i++)
+            pal[i] = bytestream2_get_le32(gb) | 0xFF000000u;
+    }
+
+    return 0;
+}
+
+static int decode_zlib(AVCodecContext *avctx, AVPacket *avpkt,
+                       unsigned size, unsigned uncompressed_size)
+{
+    RASCContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    int zret;
+
+    zret = inflateReset(&s->zstream);
+    if (zret != Z_OK) {
+        av_log(avctx, AV_LOG_ERROR, "Inflate reset error: %d\n", zret);
+        return AVERROR_EXTERNAL;
+    }
+
+    av_fast_padded_malloc(&s->delta, &s->delta_size, uncompressed_size);
+    if (!s->delta)
+        return AVERROR(ENOMEM);
+
+    s->zstream.next_in  = avpkt->data + bytestream2_tell(gb);
+    s->zstream.avail_in = FFMIN(size, bytestream2_get_bytes_left(gb));
+
+    s->zstream.next_out  = s->delta;
+    s->zstream.avail_out = s->delta_size;
+
+    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;
+    }
+
+    return 0;
+}
+
+static int decode_move(AVCodecContext *avctx,
+                       AVPacket *avpkt, unsigned size)
+{
+    RASCContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    GetByteContext mc;
+    unsigned pos, compression, nb_moves;
+    unsigned uncompressed_size;
+    int ret;
+
+    pos = bytestream2_tell(gb);
+    bytestream2_skip(gb, 8);
+    nb_moves = bytestream2_get_le32(gb);
+    bytestream2_skip(gb, 8);
+    compression = bytestream2_get_le32(gb);
+
+    if (nb_moves > INT32_MAX / 16)
+        return AVERROR_INVALIDDATA;
+
+    uncompressed_size = 16 * nb_moves;
+
+    if (compression == 1) {
+        ret = decode_zlib(avctx, avpkt,
+                          size - (bytestream2_tell(gb) - pos),
+                          uncompressed_size);
+        if (ret < 0)
+            return ret;
+        bytestream2_init(&mc, s->delta, uncompressed_size);
+    } else if (compression == 0) {
+        bytestream2_init(&mc, avpkt->data + bytestream2_tell(gb),
+                         bytestream2_get_bytes_left(gb));
+    } else if (compression == 2) {
+        avpriv_request_sample(avctx, "compression %d", compression);
+        return AVERROR_PATCHWELCOME;
+    } else {
+        return AVERROR_INVALIDDATA;
+    }
+
+    if (bytestream2_get_bytes_left(&mc) < uncompressed_size)
+        return AVERROR_INVALIDDATA;
+
+    for (int i = 0; i < nb_moves; i++) {
+        int type, start_x, start_y, end_x, end_y, mov_x, mov_y;
+        uint8_t *e2, *b1, *b2;
+        int w, h;
+
+        type = bytestream2_get_le16(&mc);
+        start_x = bytestream2_get_le16(&mc);
+        start_y = bytestream2_get_le16(&mc);
+        end_x = bytestream2_get_le16(&mc);
+        end_y = bytestream2_get_le16(&mc);
+        mov_x = bytestream2_get_le16(&mc);
+        mov_y = bytestream2_get_le16(&mc);
+        bytestream2_skip(&mc, 2);
+
+        if (start_x >= avctx->width || start_y >= avctx->height ||
+            end_x >= avctx->width || end_y >= avctx->height ||
+            mov_x >= avctx->width || mov_y >= avctx->height) {
+            continue;
+        }
+
+        if (start_x >= end_x || start_y >= end_y)
+            continue;
+
+        w = end_x - start_x;
+        h = end_y - start_y;
+
+        if (mov_x + w > avctx->width || mov_y + h > avctx->height)
+            continue;
+
+        if (!s->frame2->data[0] || !s->frame1->data[0])
+            return AVERROR_INVALIDDATA;
+
+        b1 = s->frame1->data[0] + s->frame1->linesize[0] * (start_y + h) + start_x * s->bpp;
+        b2 = s->frame2->data[0] + s->frame2->linesize[0] * (start_y + h) + start_x * s->bpp;
+        e2 = s->frame2->data[0] + s->frame2->linesize[0] * (mov_y + h) + mov_x * s->bpp;
+
+        if (type == 2) {
+            for (int j = 0; j < h; j++) {
+                memcpy(b1, b2, w * s->bpp);
+                b1 -= s->frame1->linesize[0];
+                b2 -= s->frame2->linesize[0];
+            }
+        } else if (type == 1) {
+            for (int j = 0; j < h; j++) {
+                memset(b2, 0, w * s->bpp);
+                b2 -= s->frame2->linesize[0];
+            }
+        } else if (type == 0) {
+            uint8_t *buffer;
+
+            av_fast_padded_malloc(&s->delta, &s->delta_size, w * h * s->bpp);
+            buffer = s->delta;
+            if (!buffer)
+                return AVERROR(ENOMEM);
+
+            for (int j = 0; j < h; j++) {
+                memcpy(buffer + j * w * s->bpp, e2, w * s->bpp);
+                e2 -= s->frame2->linesize[0];
+            }
+
+            for (int j = 0; j < h; j++) {
+                memcpy(b2, buffer + j * w * s->bpp, w * s->bpp);
+                b2 -= s->frame2->linesize[0];
+            }
+        } else {
+            return AVERROR_INVALIDDATA;
+        }
+    }
+
+    bytestream2_skip(gb, size - (bytestream2_tell(gb) - pos));
+
+    return 0;
+}
+
+#define NEXT_LINE                        \
+    if (cx >= w * s->bpp) {              \
+        cx = 0;                          \
+        cy--;                            \
+        b1 -= s->frame1->linesize[0];    \
+        b2 -= s->frame2->linesize[0];    \
+    }                                    \
+    len--;
+
+static int decode_dlta(AVCodecContext *avctx,
+                       AVPacket *avpkt, unsigned size)
+{
+    RASCContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    GetByteContext dc;
+    unsigned uncompressed_size, pos;
+    unsigned x, y, w, h;
+    int ret, cx, cy, compression;
+    uint8_t *b1, *b2;
+
+    pos = bytestream2_tell(gb);
+    bytestream2_skip(gb, 12);
+    uncompressed_size = bytestream2_get_le32(gb);
+    x = bytestream2_get_le32(gb);
+    y = bytestream2_get_le32(gb);
+    w = bytestream2_get_le32(gb);
+    h = bytestream2_get_le32(gb);
+
+    if (x >= avctx->width || y >= avctx->height ||
+        w > avctx->width || h > avctx->height)
+        return AVERROR_INVALIDDATA;
+
+    if (x + w > avctx->width || y + h > avctx->height)
+        return AVERROR_INVALIDDATA;
+
+    bytestream2_skip(gb, 4);
+    compression = bytestream2_get_le32(gb);
+
+    if (compression == 1) {
+        ret = decode_zlib(avctx, avpkt, size, uncompressed_size);
+        if (ret < 0)
+            return ret;
+        bytestream2_init(&dc, s->delta, uncompressed_size);
+    } else if (compression == 0) {
+        if (bytestream2_get_bytes_left(gb) < uncompressed_size)
+            return AVERROR_INVALIDDATA;
+        bytestream2_init(&dc, avpkt->data + bytestream2_tell(gb),
+                         uncompressed_size);
+    } else if (compression == 2) {
+        avpriv_request_sample(avctx, "compression %d", compression);
+        return AVERROR_PATCHWELCOME;
+    } else {
+        return AVERROR_INVALIDDATA;
+    }
+
+    if (!s->frame2->data[0] || !s->frame1->data[0])
+        return AVERROR_INVALIDDATA;
+
+    b1  = s->frame1->data[0] + s->frame1->linesize[0] * (y + h - 1) + x * s->bpp;
+    b2  = s->frame2->data[0] + s->frame2->linesize[0] * (y + h - 1) + x * s->bpp;
+    cx = 0, cy = h;
+    while (bytestream2_get_bytes_left(&dc) > 0) {
+        int type = bytestream2_get_byte(&dc);
+        int len = bytestream2_get_byte(&dc);
+        unsigned fill;
+
+        switch (type) {
+        case 1:
+            while (len > 0 && cy > 0) {
+                cx++;
+                NEXT_LINE
+            }
+            break;
+        case 2:
+            while (len > 0 && cy > 0) {
+                int v0 = b1[cx];
+                int v1 = b2[cx];
+
+                b2[cx] = v0;
+                b1[cx] = v1;
+                cx++;
+                NEXT_LINE
+            }
+            break;
+        case 3:
+            while (len > 0 && cy > 0) {
+                fill = bytestream2_get_byte(&dc);
+                b1[cx] = b2[cx];
+                b2[cx] = fill;
+                cx++;
+                NEXT_LINE
+            }
+            break;
+        case 4:
+            fill = bytestream2_get_byte(&dc);
+            while (len > 0 && cy > 0) {
+                AV_WL32(b1 + cx, AV_RL32(b2 + cx));
+                AV_WL32(b2 + cx, fill);
+                cx++;
+                NEXT_LINE
+            }
+            break;
+        case 7:
+            fill = bytestream2_get_le32(&dc);
+            while (len > 0 && cy > 0) {
+                AV_WL32(b1 + cx, AV_RL32(b2 + cx));
+                AV_WL32(b2 + cx, fill);
+                cx += 4;
+                NEXT_LINE
+            }
+            break;
+        case 10:
+            while (len > 0 && cy > 0) {
+                cx += 4;
+                NEXT_LINE
+            }
+            break;
+        case 12:
+            while (len > 0 && cy > 0) {
+                unsigned v0, v1;
+
+                v0 = AV_RL32(b2 + cx);
+                v1 = AV_RL32(b1 + cx);
+                AV_WL32(b2 + cx, v1);
+                AV_WL32(b1 + cx, v0);
+                cx += 4;
+                NEXT_LINE
+            }
+            break;
+        case 13:
+            while (len > 0 && cy > 0) {
+                fill = bytestream2_get_le32(&dc);
+                AV_WL32(b1 + cx, AV_RL32(b2 + cx));
+                AV_WL32(b2 + cx, fill);
+                cx += 4;
+                NEXT_LINE
+            }
+            break;
+        default:
+            avpriv_request_sample(avctx, "runlen %d", type);
+            return AVERROR_INVALIDDATA;
+        }
+    }
+
+    bytestream2_skip(gb, size - (bytestream2_tell(gb) - pos));
+
+    return 0;
+}
+
+static int decode_kfrm(AVCodecContext *avctx,
+                       AVPacket *avpkt, unsigned size)
+{
+    RASCContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    uint8_t *dst;
+    unsigned pos;
+    int zret, ret;
+
+    pos = bytestream2_tell(gb);
+    if (bytestream2_peek_le32(gb) == 0x65) {
+        ret = decode_fint(avctx, avpkt, size);
+        if (ret < 0)
+            return ret;
+    }
+
+    if (!s->frame2->data[0])
+        return AVERROR_INVALIDDATA;
+
+    zret = inflateReset(&s->zstream);
+    if (zret != Z_OK) {
+        av_log(avctx, AV_LOG_ERROR, "Inflate reset error: %d\n", zret);
+        return AVERROR_EXTERNAL;
+    }
+
+    s->zstream.next_in  = avpkt->data + bytestream2_tell(gb);
+    s->zstream.avail_in = bytestream2_get_bytes_left(gb);
+
+    dst = s->frame2->data[0] + (avctx->height - 1) * s->frame2->linesize[0];
+    for (int i = 0; i < avctx->height; i++) {
+        s->zstream.next_out  = dst;
+        s->zstream.avail_out = s->stride;
+
+        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 -= s->frame2->linesize[0];
+    }
+
+    dst = s->frame1->data[0] + (avctx->height - 1) * s->frame1->linesize[0];
+    for (int i = 0; i < avctx->height; i++) {
+        s->zstream.next_out  = dst;
+        s->zstream.avail_out = s->stride;
+
+        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 -= s->frame1->linesize[0];
+    }
+
+    bytestream2_skip(gb, size - (bytestream2_tell(gb) - pos));
+
+    return 0;
+}
+
+static int decode_mous(AVCodecContext *avctx,
+                       AVPacket *avpkt, unsigned size)
+{
+    RASCContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    unsigned w, h, pos, uncompressed_size;
+    int ret;
+
+    pos = bytestream2_tell(gb);
+    bytestream2_skip(gb, 8);
+    w = bytestream2_get_le32(gb);
+    h = bytestream2_get_le32(gb);
+    bytestream2_skip(gb, 12);
+    uncompressed_size = bytestream2_get_le32(gb);
+
+    if (w > avctx->width || h > avctx->height)
+        return AVERROR_INVALIDDATA;
+
+    if (uncompressed_size != 3 * w * h)
+        return AVERROR_INVALIDDATA;
+
+    av_fast_padded_malloc(&s->cursor, &s->cursor_size, uncompressed_size);
+    if (!s->cursor)
+        return AVERROR(ENOMEM);
+
+    ret = decode_zlib(avctx, avpkt,
+                      size - (bytestream2_tell(gb) - pos),
+                      uncompressed_size);
+    if (ret < 0)
+        return ret;
+    memcpy(s->cursor, s->delta, uncompressed_size);
+
+    bytestream2_skip(gb, size - (bytestream2_tell(gb) - pos));
+
+    s->cursor_w = w;
+    s->cursor_h = h;
+
+    return 0;
+}
+
+static int decode_mpos(AVCodecContext *avctx,
+                       AVPacket *avpkt, unsigned size)
+{
+    RASCContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    unsigned pos;
+
+    pos = bytestream2_tell(gb);
+    bytestream2_skip(gb, 8);
+    s->cursor_x = bytestream2_get_le32(gb);
+    s->cursor_y = bytestream2_get_le32(gb);
+
+    bytestream2_skip(gb, size - (bytestream2_tell(gb) - pos));
+
+    return 0;
+}
+
+static void draw_cursor(AVCodecContext *avctx)
+{
+    RASCContext *s = avctx->priv_data;
+    uint8_t *dst, *pal;
+
+    if (!s->cursor)
+        return;
+
+    if (s->cursor_x >= avctx->width || s->cursor_y >= avctx->height)
+        return;
+
+    if (s->cursor_x + s->cursor_w > avctx->width ||
+        s->cursor_y + s->cursor_h > avctx->height)
+        return;
+
+    if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
+        pal = s->frame->data[1];
+        for (int i = 0; i < s->cursor_h; i++) {
+            for (int j = 0; j < s->cursor_w; j++) {
+                int cr = s->cursor[3 * s->cursor_w * (s->cursor_h - i - 1) + 3 * j + 0];
+                int cg = s->cursor[3 * s->cursor_w * (s->cursor_h - i - 1) + 3 * j + 1];
+                int cb = s->cursor[3 * s->cursor_w * (s->cursor_h - i - 1) + 3 * j + 2];
+                int best = INT_MAX;
+                int index = 0;
+                int dist;
+
+                if (cr == s->cursor[0] && cg == s->cursor[1] && cb == s->cursor[2])
+                    continue;
+
+                dst = s->frame->data[0] + s->frame->linesize[0] * (s->cursor_y + i) + (s->cursor_x + j);
+                for (int k = 0; k < 256; k++) {
+                    int pr = pal[k * 4 + 0];
+                    int pg = pal[k * 4 + 1];
+                    int pb = pal[k * 4 + 2];
+
+                    dist = FFABS(cr - pr) + FFABS(cg - pg) + FFABS(cb - pb);
+                    if (dist < best) {
+                        best = dist;
+                        index = k;
+                    }
+                }
+                dst[0] = index;
+            }
+        }
+    } else if (avctx->pix_fmt == AV_PIX_FMT_RGB555LE) {
+        for (int i = 0; i < s->cursor_h; i++) {
+            for (int j = 0; j < s->cursor_w; j++) {
+                int cr = s->cursor[3 * s->cursor_w * (s->cursor_h - i - 1) + 3 * j + 0];
+                int cg = s->cursor[3 * s->cursor_w * (s->cursor_h - i - 1) + 3 * j + 1];
+                int cb = s->cursor[3 * s->cursor_w * (s->cursor_h - i - 1) + 3 * j + 2];
+
+                if (cr == s->cursor[0] && cg == s->cursor[1] && cb == s->cursor[2])
+                    continue;
+
+                cr >>= 3; cg >>=3; cb >>= 3;
+                dst = s->frame->data[0] + s->frame->linesize[0] * (s->cursor_y + i) + 2 * (s->cursor_x + j);
+                AV_WL16(dst, cr | cg << 5 | cb << 10);
+            }
+        }
+    } else if (avctx->pix_fmt == AV_PIX_FMT_BGR0) {
+        for (int i = 0; i < s->cursor_h; i++) {
+            for (int j = 0; j < s->cursor_w; j++) {
+                int cr = s->cursor[3 * s->cursor_w * (s->cursor_h - i - 1) + 3 * j + 0];
+                int cg = s->cursor[3 * s->cursor_w * (s->cursor_h - i - 1) + 3 * j + 1];
+                int cb = s->cursor[3 * s->cursor_w * (s->cursor_h - i - 1) + 3 * j + 2];
+
+                if (cr == s->cursor[0] && cg == s->cursor[1] && cb == s->cursor[2])
+                    continue;
+
+                dst = s->frame->data[0] + s->frame->linesize[0] * (s->cursor_y + i) + 4 * (s->cursor_x + j);
+                dst[0] = cb;
+                dst[1] = cg;
+                dst[2] = cr;
+            }
+        }
+    }
+}
+
+static int decode_frame(AVCodecContext *avctx,
+                        void *data, int *got_frame,
+                        AVPacket *avpkt)
+{
+    RASCContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    int ret, intra = 0;
+    AVFrame *frame = data;
+
+    bytestream2_init(gb, avpkt->data, avpkt->size);
+
+    if (bytestream2_peek_le32(gb) == EMPT)
+        return avpkt->size;
+
+    s->frame = frame;
+
+    while (bytestream2_get_bytes_left(gb) > 0) {
+        unsigned type, size = 0;
+
+        type = bytestream2_get_le32(gb);
+        if (type == KBND || type == BNDL) {
+            intra = type == KBND;
+            type = bytestream2_get_le32(gb);
+        }
+
+        size = bytestream2_get_le32(gb);
+        if (bytestream2_get_bytes_left(gb) < size)
+            return AVERROR_INVALIDDATA;
+
+        switch (type) {
+        case FINT:
+        case INIT:
+            ret = decode_fint(avctx, avpkt, size);
+            break;
+        case KFRM:
+            ret = decode_kfrm(avctx, avpkt, size);
+            break;
+        case DLTA:
+            ret = decode_dlta(avctx, avpkt, size);
+            break;
+        case MOVE:
+            ret = decode_move(avctx, avpkt, size);
+            break;
+        case MOUS:
+            ret = decode_mous(avctx, avpkt, size);
+            break;
+        case MPOS:
+            ret = decode_mpos(avctx, avpkt, size);
+            break;
+        default:
+            bytestream2_skip(gb, size);
+        }
+
+        if (ret < 0)
+            return ret;
+    }
+
+    if ((ret = ff_get_buffer(avctx, s->frame, 0)) < 0)
+        return ret;
+
+    if (!s->frame2->data[0] || !s->frame1->data[0])
+        return AVERROR_INVALIDDATA;
+
+    copy_plane(avctx, s->frame2, s->frame);
+    if (avctx->pix_fmt == AV_PIX_FMT_PAL8)
+        memcpy(s->frame->data[1], s->frame2->data[1], 1024);
+    if (!s->skip_cursor)
+        draw_cursor(avctx);
+
+    s->frame->key_frame = intra;
+    s->frame->pict_type = intra ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
+
+    *got_frame = 1;
+
+    return avpkt->size;
+}
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+    RASCContext *s = avctx->priv_data;
+    int zret;
+
+    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->frame1 = av_frame_alloc();
+    s->frame2 = av_frame_alloc();
+    if (!s->frame1 || !s->frame2)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+static av_cold int decode_close(AVCodecContext *avctx)
+{
+    RASCContext *s = avctx->priv_data;
+
+    av_freep(&s->cursor);
+    s->cursor_size = 0;
+    av_freep(&s->delta);
+    s->delta_size = 0;
+    av_frame_free(&s->frame1);
+    av_frame_free(&s->frame2);
+    inflateEnd(&s->zstream);
+
+    return 0;
+}
+
+static void decode_flush(AVCodecContext *avctx)
+{
+    RASCContext *s = avctx->priv_data;
+
+    clear_plane(avctx, s->frame1);
+    clear_plane(avctx, s->frame2);
+}
+
+static const AVOption options[] = {
+{ "skip_cursor", "skip the cursor", offsetof(RASCContext, skip_cursor), AV_OPT_TYPE_BOOL, {.i64 = 0 }, 0, 1, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_VIDEO_PARAM },
+{ NULL },
+};
+
+static const AVClass rasc_decoder_class = {
+    .class_name = "rasc decoder",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVCodec ff_rasc_decoder = {
+    .name             = "rasc",
+    .long_name        = NULL_IF_CONFIG_SMALL("RemotelyAnywhere Screen Capture"),
+    .type             = AVMEDIA_TYPE_VIDEO,
+    .id               = AV_CODEC_ID_RASC,
+    .priv_data_size   = sizeof(RASCContext),
+    .init             = decode_init,
+    .close            = decode_close,
+    .decode           = decode_frame,
+    .flush            = decode_flush,
+    .capabilities     = AV_CODEC_CAP_DR1,
+    .caps_internal    = FF_CODEC_CAP_INIT_THREADSAFE |
+                        FF_CODEC_CAP_INIT_CLEANUP,
+    .priv_class       = &rasc_decoder_class,
+};