Interplay C93 demuxer and video decoder

patch by Anssi Hannula, anssi.hannula gmail com

Originally committed as revision 8643 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 253 insertions, 0 deletions

diff --git a/libavcodec/c93.c b/libavcodec/c93.c
new file mode 100644
index 0000000000..1e90efbc2a
--- /dev/null
+++ b/libavcodec/c93.c
@@ -0,0 +1,253 @@
+/*
+ * Interplay C93 video decoder
+ * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
+ *
+ * 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 "avcodec.h"
+#include "bytestream.h"
+
+typedef struct {
+    AVFrame pictures[2];
+    int currentpic;
+} C93DecoderContext;
+
+typedef enum {
+    C93_8X8_FROM_PREV  = 0x02,
+    C93_4X4_FROM_PREV  = 0x06,
+    C93_4X4_FROM_CURR  = 0x07,
+    C93_8X8_2COLOR     = 0x08,
+    C93_4X4_2COLOR     = 0x0A,
+    C93_4X4_4COLOR_GRP = 0x0B,
+    C93_4X4_4COLOR     = 0x0D,
+    C93_NOOP           = 0x0E,
+    C93_8X8_INTRA      = 0x0F,
+} C93BlockType;
+
+#define WIDTH   320
+#define HEIGHT  192
+
+#define C93_HAS_PALETTE 0x01
+#define C93_FIRST_FRAME 0x02
+
+static int c93_decode_init(AVCodecContext *avctx)
+{
+    avctx->pix_fmt = PIX_FMT_PAL8;
+    return 0;
+}
+
+static int c93_decode_end(AVCodecContext *avctx)
+{
+    C93DecoderContext * const c93 = avctx->priv_data;
+
+    if (c93->pictures[0].data[0])
+        avctx->release_buffer(avctx, &c93->pictures[0]);
+    if (c93->pictures[1].data[0])
+        avctx->release_buffer(avctx, &c93->pictures[1]);
+    return 0;
+}
+
+static inline int c93_copy_block(AVCodecContext *avctx, uint8_t *to,
+        uint8_t *from, int offset, int height, int stride)
+{
+    int i;
+    int width = height;
+    int from_x = offset % WIDTH;
+    int from_y = offset / WIDTH;
+    int overflow = from_x + width - WIDTH;
+
+    if (!from) {
+        /* silently ignoring predictive blocks in first frame */
+        return 0;
+    }
+
+    if (from_y + height > HEIGHT) {
+        av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
+               offset);
+        return -1;
+    }
+
+    if (overflow > 0) {
+        width -= overflow;
+        for (i = 0; i < height; i++) {
+            memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
+        }
+    }
+
+    for (i = 0; i < height; i++) {
+        memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
+    }
+
+    return 0;
+}
+
+static inline void c93_draw_n_color(uint8_t *out, int stride, int width,
+         int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
+{
+    int x, y;
+    for (y = 0; y < height; y++) {
+        if (grps)
+            cols[0] = grps[3 * (y >> 1)];
+        for (x = 0; x < width; x++) {
+            if (grps)
+                cols[1]= grps[(x >> 1) + 1];
+            out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
+            col >>= bpp;
+        }
+    }
+}
+
+static int c93_decode_frame(AVCodecContext *avctx, void *data,
+                            int *data_size, uint8_t * buf, int buf_size)
+{
+    C93DecoderContext * const c93 = avctx->priv_data;
+    AVFrame * const newpic = &c93->pictures[c93->currentpic];
+    AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
+    AVFrame *picture = data;
+    uint8_t *out;
+    int stride, i, x, y;
+    C93BlockType bt = 0;
+
+    c93->currentpic ^= 1;
+
+    newpic->reference = 1;
+    newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
+                         FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
+    if (avctx->reget_buffer(avctx, newpic)) {
+        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
+        return -1;
+    }
+
+    stride = newpic->linesize[0];
+
+    if (buf[0] & C93_FIRST_FRAME) {
+        newpic->pict_type = FF_I_TYPE;
+        newpic->key_frame = 1;
+    } else {
+        newpic->pict_type = FF_P_TYPE;
+        newpic->key_frame = 0;
+    }
+
+    if (*buf++ & C93_HAS_PALETTE) {
+        uint32_t *palette = (uint32_t *) newpic->data[1];
+        uint8_t *palbuf = buf + buf_size - 768 - 1;
+        for (i = 0; i < 256; i++) {
+            palette[i] = bytestream_get_be24(&palbuf);
+        }
+    } else {
+        if (oldpic->data[1])
+            memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
+    }
+
+    for (y = 0; y < HEIGHT; y += 8) {
+        out = newpic->data[0] + y * stride;
+        for (x = 0; x < WIDTH; x += 8) {
+            uint8_t *copy_from = oldpic->data[0];
+            unsigned int offset, j;
+            uint8_t cols[4], grps[4];
+
+            if (!bt)
+                bt = *buf++;
+
+            switch (bt & 0x0F) {
+            case C93_8X8_FROM_PREV:
+                offset = bytestream_get_le16(&buf);
+                if (c93_copy_block(avctx, out, copy_from, offset, 8, stride))
+                    return -1;
+                break;
+
+            case C93_4X4_FROM_CURR:
+                copy_from = newpic->data[0];
+            case C93_4X4_FROM_PREV:
+                for (j = 0; j < 8; j += 4) {
+                    for (i = 0; i < 8; i += 4) {
+                        offset = bytestream_get_le16(&buf);
+                        if (c93_copy_block(avctx, &out[j*stride+i],
+                                           copy_from, offset, 4, stride))
+                            return -1;
+                    }
+                }
+                break;
+
+            case C93_8X8_2COLOR:
+                bytestream_get_buffer(&buf, cols, 2);
+                for (i = 0; i < 8; i++) {
+                    c93_draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
+                                     NULL, *buf++);
+                }
+
+                break;
+
+            case C93_4X4_2COLOR:
+            case C93_4X4_4COLOR:
+            case C93_4X4_4COLOR_GRP:
+                for (j = 0; j < 8; j += 4) {
+                    for (i = 0; i < 8; i += 4) {
+                        if ((bt & 0x0F) == C93_4X4_2COLOR) {
+                            bytestream_get_buffer(&buf, cols, 2);
+                            c93_draw_n_color(out + i + j*stride, stride, 4, 4,
+                                    1, cols, NULL, bytestream_get_le16(&buf));
+                        } else if ((bt & 0x0F) == C93_4X4_4COLOR) {
+                            bytestream_get_buffer(&buf, cols, 4);
+                            c93_draw_n_color(out + i + j*stride, stride, 4, 4,
+                                    2, cols, NULL, bytestream_get_le32(&buf));
+                        } else {
+                            bytestream_get_buffer(&buf, grps, 4);
+                            c93_draw_n_color(out + i + j*stride, stride, 4, 4,
+                                    1, cols, grps, bytestream_get_le16(&buf));
+                        }
+                    }
+                }
+                break;
+
+            case C93_NOOP:
+                break;
+
+            case C93_8X8_INTRA:
+                for (j = 0; j < 8; j++)
+                    bytestream_get_buffer(&buf, out + j*stride, 8);
+                break;
+
+            default:
+                av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
+                       bt & 0x0F, x, y);
+                return -1;
+            }
+            bt >>= 4;
+            out += 8;
+        }
+    }
+
+    *picture = *newpic;
+    *data_size = sizeof(AVFrame);
+
+    return buf_size;
+}
+
+AVCodec c93_decoder = {
+    "c93",
+    CODEC_TYPE_VIDEO,
+    CODEC_ID_C93,
+    sizeof(C93DecoderContext),
+    c93_decode_init,
+    NULL,
+    c93_decode_end,
+    c93_decode_frame,
+    CODEC_CAP_DR1,
+};