avcodec: add ARBC decoder

Thanks Kostya for great help in reversing binary.

1 files changed, 204 insertions, 0 deletions

diff --git a/libavcodec/arbc.c b/libavcodec/arbc.c
new file mode 100644
index 0000000000..01a146f934
--- /dev/null
+++ b/libavcodec/arbc.c
@@ -0,0 +1,204 @@
+/*
+ * Gryphon's Anim Compressor decoder
+ * Copyright (c) 2019 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/imgutils.h"
+#include "libavutil/internal.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/mem.h"
+
+#include "avcodec.h"
+#include "bytestream.h"
+#include "internal.h"
+
+typedef struct ARBCContext {
+    GetByteContext gb;
+
+    AVFrame *prev_frame;
+} ARBCContext;
+
+static void fill_tile4(AVCodecContext *avctx, uint8_t *color, AVFrame *frame)
+{
+    ARBCContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    int nb_tiles = bytestream2_get_le16(gb);
+    int h = avctx->height - 1;
+
+    for (int i = 0; i < nb_tiles; i++) {
+        int y = bytestream2_get_byte(gb);
+        int x = bytestream2_get_byte(gb);
+        uint16_t mask = bytestream2_get_le16(gb);
+        int start_y = y * 4, start_x = x * 4;
+        int end_y = start_y + 4, end_x = start_x + 4;
+
+        for (int j = start_y; j < end_y; j++) {
+            for (int k = start_x; k < end_x; k++) {
+                if (mask & 0x8000) {
+                    if (j >= avctx->height || k >= avctx->width) {
+                        mask = mask << 1;
+                        continue;
+                    }
+                    frame->data[0][frame->linesize[0] * (h - j) + 3 * k + 0] = color[0];
+                    frame->data[0][frame->linesize[0] * (h - j) + 3 * k + 1] = color[1];
+                    frame->data[0][frame->linesize[0] * (h - j) + 3 * k + 2] = color[2];
+                }
+                mask = mask << 1;
+            }
+        }
+    }
+}
+
+static void fill_tileX(AVCodecContext *avctx, int tile_width, int tile_height,
+                       uint8_t *color, AVFrame *frame)
+{
+    ARBCContext *s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    const int step_h = tile_height / 4;
+    const int step_w = tile_width / 4;
+    int nb_tiles = bytestream2_get_le16(gb);
+    int h = avctx->height - 1;
+
+    for (int i = 0; i < nb_tiles; i++) {
+        int y = bytestream2_get_byte(gb);
+        int x = bytestream2_get_byte(gb);
+        uint16_t mask = bytestream2_get_le16(gb);
+        int start_y = y * tile_height, start_x = x * tile_width;
+        int end_y = start_y + tile_height, end_x = start_x + tile_width;
+
+        for (int j = start_y; j < end_y; j += step_h) {
+            for (int k = start_x; k < end_x; k += step_w) {
+                if (mask & 0x8000U) {
+                    for (int m = 0; m < step_h; m++) {
+                        for (int n = 0; n < step_w; n++) {
+                            if (j + m >= avctx->height || k + n >= avctx->width)
+                                continue;
+                            frame->data[0][frame->linesize[0] * (h - (j + m)) + 3 * (k + n) + 0] = color[0];
+                            frame->data[0][frame->linesize[0] * (h - (j + m)) + 3 * (k + n) + 1] = color[1];
+                            frame->data[0][frame->linesize[0] * (h - (j + m)) + 3 * (k + n) + 2] = color[2];
+                        }
+                    }
+                }
+                mask = mask << 1;
+            }
+        }
+    }
+}
+
+static int decode_frame(AVCodecContext *avctx, void *data,
+                        int *got_frame, AVPacket *avpkt)
+{
+    ARBCContext *s = avctx->priv_data;
+    AVFrame *frame = data;
+    int ret, nb_segments, keyframe = 1;
+
+    if (avpkt->size < 10)
+        return AVERROR_INVALIDDATA;
+
+    if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
+        return ret;
+
+    if (s->prev_frame->data[0]) {
+        ret = av_frame_copy(frame, s->prev_frame);
+        if (ret < 0)
+            return ret;
+    }
+
+    bytestream2_init(&s->gb, avpkt->data, avpkt->size);
+    bytestream2_skip(&s->gb, 8);
+    nb_segments = bytestream2_get_le16(&s->gb);
+    if (nb_segments == 0)
+        keyframe = 0;
+
+    for (int i = 0; i < nb_segments; i++) {
+        int resolution_flag;
+        uint8_t fill[3];
+
+        if (bytestream2_get_bytes_left(&s->gb) <= 0)
+            return AVERROR_INVALIDDATA;
+
+        fill[0] = bytestream2_get_byte(&s->gb);
+        bytestream2_skip(&s->gb, 1);
+        fill[1] = bytestream2_get_byte(&s->gb);
+        bytestream2_skip(&s->gb, 1);
+        fill[2] = bytestream2_get_byte(&s->gb);
+        bytestream2_skip(&s->gb, 1);
+        resolution_flag = bytestream2_get_byte(&s->gb);
+
+        if (resolution_flag & 0x10)
+            fill_tileX(avctx, 1024, 1024, fill, frame);
+        if (resolution_flag & 0x08)
+            fill_tileX(avctx, 256, 256, fill, frame);
+        if (resolution_flag & 0x04)
+            fill_tileX(avctx, 64, 64, fill, frame);
+        if (resolution_flag & 0x02)
+            fill_tileX(avctx, 16, 16, fill, frame);
+        if (resolution_flag & 0x01)
+            fill_tile4(avctx, fill, frame);
+    }
+
+    av_frame_unref(s->prev_frame);
+    if ((ret = av_frame_ref(s->prev_frame, frame)) < 0)
+        return ret;
+
+    frame->pict_type = keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
+    frame->key_frame = keyframe;
+    *got_frame = 1;
+
+    return avpkt->size;
+}
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+    ARBCContext *s = avctx->priv_data;
+
+    avctx->pix_fmt = AV_PIX_FMT_RGB24;
+
+    s->prev_frame = av_frame_alloc();
+    if (!s->prev_frame)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+static av_cold int decode_close(AVCodecContext *avctx)
+{
+    ARBCContext *s = avctx->priv_data;
+
+    av_frame_free(&s->prev_frame);
+
+    return 0;
+}
+
+AVCodec ff_arbc_decoder = {
+    .name           = "arbc",
+    .long_name      = NULL_IF_CONFIG_SMALL("Gryphon's Anim Compressor"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_ARBC,
+    .priv_data_size = sizeof(ARBCContext),
+    .init           = decode_init,
+    .decode         = decode_frame,
+    .close          = decode_close,
+    .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
+};