Kega Game Video (KGV1) decoder

Originally committed as revision 22364 to svn://svn.ffmpeg.org/ffmpeg/trunk

Changelog

@@ -62,6 +62,7 @@ version <next>:
 - AMR-NB decoder
 - RTSP muxer
 - HE-AAC v1 decoder
+- Kega Game Video (KGV1) decoder
 
 
 

doc/general.texi

@@ -403,6 +403,8 @@ following image formats are supported:
     @tab Used in Interplay .MVE files.
 @item Karl Morton's video codec  @tab     @tab  X
     @tab Codec used in Worms games.
+@item Kega Game Video (KGV1) @tab      @tab  X
+    @tab Kega emulator screen capture codec.
 @item LCL (LossLess Codec Library) MSZH  @tab     @tab  X
 @item LCL (LossLess Codec Library) ZLIB  @tab  E  @tab  E
 @item LOCO                   @tab     @tab  X

libavcodec/Makefile

@@ -167,6 +167,7 @@ OBJS-$(CONFIG_INTERPLAY_VIDEO_DECODER) += interplayvideo.o
 OBJS-$(CONFIG_JPEGLS_DECODER)          += jpeglsdec.o jpegls.o \
                                           mjpegdec.o mjpeg.o
 OBJS-$(CONFIG_JPEGLS_ENCODER)          += jpeglsenc.o jpegls.o
+OBJS-$(CONFIG_KGV1_DECODER)            += kgv1dec.o
 OBJS-$(CONFIG_KMVC_DECODER)            += kmvc.o
 OBJS-$(CONFIG_LJPEG_ENCODER)           += ljpegenc.o mjpegenc.o mjpeg.o \
                                           mpegvideo_enc.o motion_est.o  \

libavcodec/allcodecs.c

@@ -122,6 +122,7 @@ void avcodec_register_all(void)
     REGISTER_DECODER (INDEO5, indeo5);
     REGISTER_DECODER (INTERPLAY_VIDEO, interplay_video);
     REGISTER_ENCDEC  (JPEGLS, jpegls);
+    REGISTER_DECODER (KGV1, kgv1);
     REGISTER_DECODER (KMVC, kmvc);
     REGISTER_ENCODER (LJPEG, ljpeg);
     REGISTER_DECODER (LOCO, loco);

libavcodec/avcodec.h

@@ -206,6 +206,7 @@ enum CodecID {
     CODEC_ID_BINKVIDEO,
     CODEC_ID_IFF_ILBM,
     CODEC_ID_IFF_BYTERUN1,
+    CODEC_ID_KGV1,
 
     /* various PCM "codecs" */
     CODEC_ID_PCM_S16LE= 0x10000,

libavcodec/kgv1dec.c

@@ -0,0 +1,176 @@
+/*
+ * 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 libavcodec/kgv1dec.c
+ * Kega Game Video decoder
+ */
+
+#include "libavutil/intreadwrite.h"
+#include "avcodec.h"
+
+typedef struct {
+    AVCodecContext *avctx;
+    AVFrame pic;
+    uint16_t *prev, *cur;
+} KgvContext;
+
+static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
+{
+    const uint8_t *buf = avpkt->data;
+    const uint8_t *buf_end = buf + avpkt->size;
+    KgvContext * const c = avctx->priv_data;
+    int offsets[7];
+    uint16_t *out, *prev;
+    int outcnt = 0, maxcnt;
+    int w, h, i;
+
+    if (avpkt->size < 2)
+        return -1;
+
+    w = (buf[0] + 1) * 8;
+    h = (buf[1] + 1) * 8;
+    buf += 2;
+
+    if (avcodec_check_dimensions(avctx, w, h))
+        return -1;
+
+    if (w != avctx->width || h != avctx->height)
+        avcodec_set_dimensions(avctx, w, h);
+
+    maxcnt = w * h;
+
+    out = av_realloc(c->cur, w * h * 2);
+    if (!out)
+        return -1;
+    c->cur = out;
+
+    prev = av_realloc(c->prev, w * h * 2);
+    if (!prev)
+        return -1;
+    c->prev = prev;
+
+    for (i = 0; i < 7; i++)
+        offsets[i] = -1;
+
+    while (outcnt < maxcnt && buf_end - 2 > buf) {
+        int code = AV_RL16(buf);
+        buf += 2;
+
+        if (!(code & 0x8000)) {
+            out[outcnt++] = code; // rgb555 pixel coded directly
+        } else {
+            int count;
+            uint16_t *inp;
+
+            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)
+                    break;
+
+                inp = prev + start;
+            } 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)
+                    break;
+
+                inp = out + outcnt - offset;
+            }
+
+            if (maxcnt - outcnt < count)
+                break;
+
+            for (i = 0; i < count; i++)
+                out[outcnt++] = inp[i];
+        }
+    }
+
+    if (outcnt - maxcnt)
+        av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
+
+    c->pic.data[0]     = (uint8_t *)c->cur;
+    c->pic.linesize[0] = w * 2;
+
+    *data_size = sizeof(AVFrame);
+    *(AVFrame*)data = c->pic;
+
+    FFSWAP(uint16_t *, c->cur, c->prev);
+
+    return avpkt->size;
+}
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+    KgvContext * const c = avctx->priv_data;
+
+    c->avctx = avctx;
+    avctx->pix_fmt = PIX_FMT_RGB555;
+
+    return 0;
+}
+
+static av_cold int decode_end(AVCodecContext *avctx)
+{
+    KgvContext * const c = avctx->priv_data;
+
+    av_freep(&c->cur);
+    av_freep(&c->prev);
+
+    return 0;
+}
+
+AVCodec kgv1_decoder = {
+    "kgv1",
+    CODEC_TYPE_VIDEO,
+    CODEC_ID_KGV1,
+    sizeof(KgvContext),
+    decode_init,
+    NULL,
+    decode_end,
+    decode_frame,
+    .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"),
+};

libavformat/riff.c

@@ -240,6 +240,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
     { CODEC_ID_AURA,         MKTAG('A', 'U', 'R', 'A') },
     { CODEC_ID_AURA2,        MKTAG('A', 'U', 'R', '2') },
     { CODEC_ID_DPX,          MKTAG('d', 'p', 'x', ' ') },
+    { CODEC_ID_KGV1,         MKTAG('K', 'G', 'V', '1') },
     { CODEC_ID_NONE,         0 }
 };