avcodec: add Simbiosis IMX video decoder

1 files changed, 153 insertions, 0 deletions

diff --git a/libavcodec/imx.c b/libavcodec/imx.c
new file mode 100644
index 0000000000..1552a4ebea
--- /dev/null
+++ b/libavcodec/imx.c
@@ -0,0 +1,153 @@
+/*
+ * 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/common.h"
+#include "avcodec.h"
+#include "bytestream.h"
+#include "internal.h"
+
+typedef struct SimbiosisIMXContext {
+    uint32_t pal[256];
+    uint8_t history[32768];
+    int pos;
+} SimbiosisIMXContext;
+
+static av_cold int imx_decode_init(AVCodecContext *avctx)
+{
+    avctx->pix_fmt = AV_PIX_FMT_PAL8;
+    avctx->width   = 320;
+    avctx->height  = 160;
+    return 0;
+}
+
+static int imx_decode_frame(AVCodecContext *avctx, void *data,
+                            int *got_frame, AVPacket *avpkt)
+{
+    SimbiosisIMXContext *imx = avctx->priv_data;
+    int ret, x, y, pal_size;
+    const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, &pal_size);
+    AVFrame *frame = data;
+    GetByteContext gb;
+
+    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
+        return ret;
+
+    if (pal && pal_size == AVPALETTE_SIZE) {
+        memcpy(imx->pal, pal, pal_size);
+        frame->palette_has_changed = 1;
+    }
+
+    bytestream2_init(&gb, avpkt->data, avpkt->size);
+
+    memcpy(frame->data[1], imx->pal, AVPALETTE_SIZE);
+
+    x = 0, y = 0;
+    while (bytestream2_get_bytes_left(&gb) > 0 &&
+           x < 320 && y < 160) {
+        int b = bytestream2_get_byte(&gb);
+        int len = b & 0x3f;
+        int op = b >> 6;
+        int fill;
+
+        switch (op) {
+        case 3:
+            len = len * 64 + bytestream2_get_byte(&gb);
+        case 0:
+            while (len > 0) {
+                x++;
+                len--;
+                if (x >= 320) {
+                    x = 0;
+                    y++;
+                }
+                if (y >= 160)
+                    break;
+            }
+            break;
+        case 1:
+            if (len == 0) {
+                int offset = bytestream2_get_le16(&gb);
+
+                if (offset < 0 || offset >= 32768)
+                    return AVERROR_INVALIDDATA;
+
+                len = bytestream2_get_byte(&gb);
+                while (len > 0 && offset < 32768) {
+                    frame->data[0][x + y * frame->linesize[0]] = imx->history[offset++];
+                    x++;
+                    len--;
+                    if (x >= 320) {
+                        x = 0;
+                        y++;
+                    }
+                    if (y >= 160)
+                        break;
+                }
+            } else {
+                while (len > 0) {
+                    fill = bytestream2_get_byte(&gb);
+                    frame->data[0][x + y * frame->linesize[0]] = fill;
+                    if (imx->pos < 32768)
+                        imx->history[imx->pos++] = fill;
+                    x++;
+                    len--;
+                    if (x >= 320) {
+                        x = 0;
+                        y++;
+                    }
+                    if (y >= 160)
+                        break;
+                }
+            }
+            break;
+        case 2:
+            fill = bytestream2_get_byte(&gb);
+
+            while (len > 0) {
+                frame->data[0][x + y * frame->linesize[0]] = fill;
+                x++;
+                len--;
+                if (x >= 320) {
+                    x = 0;
+                    y++;
+                }
+                if (y >= 160)
+                    break;
+            }
+            break;
+        }
+    }
+
+    *got_frame = 1;
+
+    return avpkt->size;
+}
+
+AVCodec ff_simbiosis_imx_decoder = {
+    .name           = "simbiosis_imx",
+    .long_name      = NULL_IF_CONFIG_SMALL("Simbiosis Interactive IMX Video"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_SIMBIOSIS_IMX,
+    .priv_data_size = sizeof(SimbiosisIMXContext),
+    .init           = imx_decode_init,
+    .decode         = imx_decode_frame,
+    .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
+};