Initial version of the a64 (multicolor charset) codec

Originally committed as revision 24873 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/a64enc.h

+/*
+ * a64 video encoder - basic headers
+ * Copyright (c) 2009 Tobias Bindhammer
+ *
+ * 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
+ * a64 video encoder - basic headers
+ */
+
+#ifndef AVCODEC_A64ENC_H
+#define AVCODEC_A64ENC_H
+
+#include "libavutil/lfg.h"
+#include "avcodec.h"
+
+#define C64XRES 320
+#define C64YRES 200
+
+typedef struct A64Context {
+    /* general variables */
+    AVFrame picture;
+
+    /* variables for multicolor modes */
+    AVLFG randctx;
+    int mc_lifetime;
+    int mc_use_5col;
+    int mc_frame_counter;
+    int *mc_meta_charset;
+    int *mc_charmap;
+    int *mc_best_cb;
+} A64Context;
+
+#endif /* AVCODEC_A64ENC_H */

libavcodec/a64multienc.c

+/*
+ * a64 video encoder - multicolor modes
+ * Copyright (c) 2009 Tobias Bindhammer
+ *
+ * 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
+ * a64 video encoder - multicolor modes
+ */
+
+#include "a64enc.h"
+#include "a64tables.h"
+#include "elbg.h"
+#include "libavutil/intreadwrite.h"
+
+#define DITHERSTEPS 8
+
+static void to_meta_with_crop(AVCodecContext *avctx, AVFrame *p, int *dest)
+{
+    int blockx, blocky, x, y;
+    int luma = 0;
+    int height = FFMIN(avctx->height,C64YRES);
+    int width  = FFMIN(avctx->width ,C64XRES);
+    uint8_t *src = p->data[0];
+
+    for (blocky = 0; blocky < height; blocky += 8) {
+        for (blockx = 0; blockx < C64XRES; blockx += 8) {
+            for (y = blocky; y < blocky+8 && y < height; y++) {
+                for (x = blockx; x < blockx+8 && x < C64XRES; x += 2) {
+                    if(x < width) {
+                        /* build average over 2 pixels */
+                        luma = (src[(x + 0 + y * p->linesize[0])] +
+                                src[(x + 1 + y * p->linesize[0])]) / 2;
+                        /* write blocks as linear data now so they are suitable for elbg */
+                        dest[0] = luma;
+                    }
+                    dest++;
+                }
+            }
+        }
+    }
+}
+
+static void render_charset(AVCodecContext *avctx, uint8_t *charset,
+                           uint8_t *colrammap)
+{
+    A64Context *c = avctx->priv_data;
+    uint8_t row1;
+    int charpos, x, y;
+    int pix;
+    int dither;
+    int index1, index2;
+    int lowdiff, highdiff;
+    int maxindex = c->mc_use_5col + 3;
+    int maxsteps = DITHERSTEPS * maxindex + 1;
+    int *best_cb = c->mc_best_cb;
+
+    /* now reduce colors first */
+    for (x = 0; x < 256 * 32; x++) best_cb[x] = best_cb[x] * maxsteps / 255;
+
+    /* and render charset */
+    for (charpos = 0; charpos < 256; charpos++) {
+        lowdiff  = 0;
+        highdiff = 0;
+        for (y = 0; y < 8; y++) {
+            row1 = 0;
+            for (x = 0; x < 4; x++) {
+                pix = best_cb[y * 4 + x];
+                dither = pix % DITHERSTEPS;
+                index1 = pix / DITHERSTEPS;
+                index2 = FFMIN(index1 + 1, maxindex);
+
+                if (pix > 3 * DITHERSTEPS)
+                    highdiff += pix - 3 * DITHERSTEPS;
+                if (pix < DITHERSTEPS)
+                    lowdiff += DITHERSTEPS - pix;
+
+                row1 <<= 2;
+                if (prep_dither_patterns[dither][y & 3][x & 3]) {
+                    row1 |= 3-(index2 & 3);
+                } else {
+                    row1 |= 3-(index1 & 3);
+                }
+            }
+            charset[y] = row1;
+        }
+
+        /* are we in 5col mode and need to adjust pixels? */
+        if (c->mc_use_5col && highdiff > 0 && lowdiff > 0) {
+            if (lowdiff > highdiff) {
+                for (x = 0; x < 32; x++)
+                    best_cb[x] = FFMIN(3 * DITHERSTEPS, best_cb[x]);
+            } else {
+                for (x = 0; x < 32; x++)
+                    best_cb[x] = FFMAX(DITHERSTEPS, best_cb[x]);
+            }
+            charpos--;          /* redo char */
+        } else {
+            /* advance pointers */
+            best_cb += 32;
+            charset += 8;
+
+            if (highdiff > 0) {
+                colrammap[charpos] = 0x9;
+            } else {
+                colrammap[charpos] = 0x8;
+            }
+        }
+    }
+}
+
+static av_cold int a64multi_close_encoder(AVCodecContext *avctx)
+{
+    A64Context *c = avctx->priv_data;
+    av_free(c->mc_meta_charset);
+    av_free(c->mc_best_cb);
+    av_free(c->mc_charmap);
+    return 0;
+}
+
+static av_cold int a64multi_init_encoder(AVCodecContext *avctx)
+{
+    A64Context *c = avctx->priv_data;
+    av_lfg_init(&c->randctx, 1);
+
+    if (avctx->global_quality < 1) {
+        c->mc_lifetime = 4;
+    } else {
+        c->mc_lifetime = avctx->global_quality /= FF_QP2LAMBDA;
+    }
+
+    av_log(avctx, AV_LOG_INFO, "charset lifetime set to %d frame(s)\n", c->mc_lifetime);
+
+    c->mc_frame_counter = 0;
+    c->mc_use_5col      = avctx->codec->id == CODEC_ID_A64_MULTI5;
+    c->mc_meta_charset  = av_malloc(32000 * c->mc_lifetime * sizeof(int));
+    c->mc_best_cb       = av_malloc(256 * 32 * sizeof(int));
+    c->mc_charmap       = av_malloc(1000 * c->mc_lifetime * sizeof(int));
+
+    avcodec_get_frame_defaults(&c->picture);
+    avctx->coded_frame            = &c->picture;
+    avctx->coded_frame->pict_type = FF_I_TYPE;
+    avctx->coded_frame->key_frame = 1;
+    if (!avctx->codec_tag)
+         avctx->codec_tag = AV_RL32("a64m");
+
+    return 0;
+}
+
+static int a64multi_encode_frame(AVCodecContext *avctx, unsigned char *buf,
+                                 int buf_size, void *data)
+{
+    A64Context *c = avctx->priv_data;
+    AVFrame *pict = data;
+    AVFrame *const p = (AVFrame *) & c->picture;
+
+    int frame;
+    int a;
+
+    uint8_t colrammap[256];
+    int *charmap = c->mc_charmap;
+    int *meta    = c->mc_meta_charset;
+    int *best_cb = c->mc_best_cb;
+    int frm_size = 0x400 + 0x400 * c->mc_use_5col;
+    int req_size;
+
+    /* it is the last frame so prepare to flush */
+    if (!data)
+        c->mc_lifetime = c->mc_frame_counter;
+
+    req_size = 0x800 + frm_size * c->mc_lifetime;
+
+    if (req_size > buf_size) {
+        av_log(avctx, AV_LOG_ERROR, "buf size too small (need %d, got %d)\n", req_size, buf_size);
+        return -1;
+    }
+    /* fill up mc_meta_charset with framedata until lifetime exceeds */
+    if (c->mc_frame_counter < c->mc_lifetime) {
+        *p = *pict;
+        p->pict_type = FF_I_TYPE;
+        p->key_frame = 1;
+        to_meta_with_crop(avctx, p, meta + 32000 * c->mc_frame_counter);
+        c->mc_frame_counter++;
+        /* lifetime is not reached */
+        return 0;
+    }
+    /* lifetime exceeded so now convert X frames at once */
+    if (c->mc_frame_counter == c->mc_lifetime && c->mc_lifetime > 0) {
+        c->mc_frame_counter = 0;
+        ff_init_elbg(meta, 32, 1000 * c-> mc_lifetime, best_cb, 256, 5, charmap, &c->randctx);
+        ff_do_elbg  (meta, 32, 1000 * c-> mc_lifetime, best_cb, 256, 5, charmap, &c->randctx);
+
+        render_charset(avctx, buf, colrammap);
+
+        for (frame = 0; frame < c->mc_lifetime; frame++) {
+            for (a = 0; a < 1000; a++) {
+                buf[0x800 + a] = charmap[a];
+                if (c->mc_use_5col) buf[0xc00 + a] = colrammap[charmap[a]];
+            }
+            buf += frm_size;
+            charmap += 1000;
+        }
+        return req_size;
+    }
+    return 0;
+}
+
+AVCodec a64multi_encoder = {
+    .name           = "a64multi",
+    .type           = CODEC_TYPE_VIDEO,
+    .id             = CODEC_ID_A64_MULTI,
+    .priv_data_size = sizeof(A64Context),
+    .init           = a64multi_init_encoder,
+    .encode         = a64multi_encode_frame,
+    .close          = a64multi_close_encoder,
+    .pix_fmts       = (enum PixelFormat[]) {PIX_FMT_GRAY8, PIX_FMT_NONE},
+    .long_name      = NULL_IF_CONFIG_SMALL("Multicolor charset for Commodore 64"),
+    .capabilities   = CODEC_CAP_DELAY,
+};
+
+AVCodec a64multi5_encoder = {
+    .name           = "a64multi5",
+    .type           = CODEC_TYPE_VIDEO,
+    .id             = CODEC_ID_A64_MULTI5,
+    .priv_data_size = sizeof(A64Context),
+    .init           = a64multi_init_encoder,
+    .encode         = a64multi_encode_frame,
+    .close          = a64multi_close_encoder,
+    .pix_fmts       = (enum PixelFormat[]) {PIX_FMT_GRAY8, PIX_FMT_NONE},
+    .long_name      = NULL_IF_CONFIG_SMALL("Multicolor charset for Commodore 64, extended with 5th color (colram)"),
+    .capabilities   = CODEC_CAP_DELAY,
+};

libavcodec/a64tables.h

+/*
+ * a64 video encoder - tables used by a64 encoders
+ * Copyright (c) 2009 Tobias Bindhammer
+ *
+ * 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
+ * a64 video encoder - tables used by a64 encoders
+ */
+
+#ifndef AVCODEC_A64TABLES_H
+#define AVCODEC_A64TABLES_H
+
+#include <stdint.h>
+
+/**
+ * dither patterns used vor rendering the multicolor charset
+ */
+static const uint8_t prep_dither_patterns[9][4][4] = {
+    {
+     {0, 0, 0, 0},
+     {0, 0, 0, 0},
+     {0, 0, 0, 0},
+     {0, 0, 0, 0}
+     },
+    {
+     {1, 0, 0, 0},
+     {0, 0, 0, 0},
+     {0, 0, 1, 0},
+     {0, 0, 0, 0}
+     },
+    {
+     {1, 0, 0, 0},
+     {0, 0, 1, 0},
+     {0, 1, 0, 0},
+     {0, 0, 0, 1}
+     },
+    {
+     {1, 0, 0, 0},
+     {0, 1, 0, 1},
+     {0, 0, 1, 0},
+     {0, 1, 0, 1}
+     },
+    {
+     {1, 0, 1, 0},
+     {0, 1, 0, 1},
+     {1, 0, 1, 0},
+     {0, 1, 0, 1}
+     },
+    {
+     {1, 1, 1, 0},
+     {0, 1, 0, 1},
+     {1, 0, 1, 1},
+     {0, 1, 0, 1}
+     },
+    {
+     {0, 1, 1, 1},
+     {1, 1, 0, 1},
+     {1, 0, 1, 1},
+     {1, 1, 1, 0}
+     },
+    {
+     {0, 1, 1, 1},
+     {1, 1, 1, 1},
+     {1, 1, 0, 1},
+     {1, 1, 1, 1}
+     },
+    {
+     {1, 1, 1, 1},
+     {1, 1, 1, 1},
+     {1, 1, 1, 1},
+     {1, 1, 1, 1}
+     },
+};
+
+#endif /* AVCODEC_A64TABLES_H */