diff ffmpeg/libavcodec/kgv1dec.c @ 10:6840f77b83aa

commit

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ffmpeg/libavcodec/kgv1dec.c	Sun Apr 21 10:55:35 2013 +0200
@@ -0,0 +1,185 @@
+/*
+ * Kega Game Video (KGV1) decoder
+ * Copyright (c) 2010 Daniel Verkamp
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * Kega Game Video decoder
+ */
+
+#include "libavutil/common.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/imgutils.h"
+#include "avcodec.h"
+#include "internal.h"
+
+typedef struct {
+    AVCodecContext *avctx;
+    AVFrame prev;
+} KgvContext;
+
+static void decode_flush(AVCodecContext *avctx)
+{
+    KgvContext * const c = avctx->priv_data;
+
+    av_frame_unref(&c->prev);
+}
+
+static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
+                        AVPacket *avpkt)
+{
+    AVFrame *frame = data;
+    const uint8_t *buf = avpkt->data;
+    const uint8_t *buf_end = buf + avpkt->size;
+    KgvContext * const c = avctx->priv_data;
+    int offsets[8];
+    uint8_t *out, *prev;
+    int outcnt = 0, maxcnt;
+    int w, h, i, res;
+
+    if (avpkt->size < 2)
+        return AVERROR_INVALIDDATA;
+
+    w = (buf[0] + 1) * 8;
+    h = (buf[1] + 1) * 8;
+    buf += 2;
+
+    if ((res = av_image_check_size(w, h, 0, avctx)) < 0)
+        return res;
+
+    if (w != avctx->width || h != avctx->height) {
+        av_frame_unref(&c->prev);
+        avcodec_set_dimensions(avctx, w, h);
+    }
+
+    maxcnt = w * h;
+
+    if ((res = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
+        return res;
+    out  = frame->data[0];
+    if (c->prev.data[0]) {
+        prev = c->prev.data[0];
+    } else {
+        prev = NULL;
+    }
+
+    for (i = 0; i < 8; i++)
+        offsets[i] = -1;
+
+    while (outcnt < maxcnt && buf_end - 2 >= buf) {
+        int code = AV_RL16(buf);
+        buf += 2;
+
+        if (!(code & 0x8000)) {
+            AV_WN16A(&out[2 * outcnt], code); // rgb555 pixel coded directly
+            outcnt++;
+        } else {
+            int count;
+
+            if ((code & 0x6000) == 0x6000) {
+                // copy from previous frame
+                int oidx = (code >> 10) & 7;
+                int start;
+
+                count = (code & 0x3FF) + 3;
+
+                if (offsets[oidx] < 0) {
+                    if (buf_end - 3 < buf)
+                        break;
+                    offsets[oidx] = AV_RL24(buf);
+                    buf += 3;
+                }
+
+                start = (outcnt + offsets[oidx]) % maxcnt;
+
+                if (maxcnt - start < count || maxcnt - outcnt < count)
+                    break;
+
+                if (!prev) {
+                    av_log(avctx, AV_LOG_ERROR,
+                           "Frame reference does not exist\n");
+                    break;
+                }
+
+                memcpy(out + 2 * outcnt, prev + 2 * start, 2 * count);
+            } else {
+                // copy from earlier in this frame
+                int offset = (code & 0x1FFF) + 1;
+
+                if (!(code & 0x6000)) {
+                    count = 2;
+                } else if ((code & 0x6000) == 0x2000) {
+                    count = 3;
+                } else {
+                    if (buf_end - 1 < buf)
+                        break;
+                    count = 4 + *buf++;
+                }
+
+                if (outcnt < offset || maxcnt - outcnt < count)
+                    break;
+
+                av_memcpy_backptr(out + 2 * outcnt, 2 * offset, 2 * count);
+            }
+            outcnt += count;
+        }
+    }
+
+    if (outcnt - maxcnt)
+        av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
+
+    av_frame_unref(&c->prev);
+    if ((res = av_frame_ref(&c->prev, frame)) < 0)
+        return res;
+
+    *got_frame = 1;
+
+    return avpkt->size;
+}
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+    KgvContext * const c = avctx->priv_data;
+
+    c->avctx = avctx;
+    avctx->pix_fmt = AV_PIX_FMT_RGB555;
+    avctx->flags  |= CODEC_FLAG_EMU_EDGE;
+
+    return 0;
+}
+
+static av_cold int decode_end(AVCodecContext *avctx)
+{
+    decode_flush(avctx);
+    return 0;
+}
+
+AVCodec ff_kgv1_decoder = {
+    .name           = "kgv1",
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_KGV1,
+    .priv_data_size = sizeof(KgvContext),
+    .init           = decode_init,
+    .close          = decode_end,
+    .decode         = decode_frame,
+    .flush          = decode_flush,
+    .long_name      = NULL_IF_CONFIG_SMALL("Kega Game Video"),
+    .capabilities   = CODEC_CAP_DR1,
+};