libavcodec/qtrleenc.c

   1 /*
   2  * Quicktime Animation (RLE) Video Encoder
   3  * Copyright (C) 2007 Clemens Fruhwirth
   4  * Copyright (C) 2007 Alexis Ballier
   5  *
   6  * This file is based on flashsvenc.c.
   7  *
   8  * This file is part of Libav.
   9  *
  10  * Libav is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2.1 of the License, or (at your option) any later version.
  14  *
  15  * Libav is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public
  21  * License along with Libav; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 #include "libavutil/imgutils.h"
  26 #include "avcodec.h"
  27 #include "bytestream.h"
  28 #include "internal.h"
  29
  30 /** Maximum RLE code for bulk copy */
  31 #define MAX_RLE_BULK   127
  32 /** Maximum RLE code for repeat */
  33 #define MAX_RLE_REPEAT 128
  34 /** Maximum RLE code for skip */
  35 #define MAX_RLE_SKIP   254
  36
  37 typedef struct QtrleEncContext {
  38     AVCodecContext *avctx;
  39     AVFrame frame;
  40     int pixel_size;
  41     AVPicture previous_frame;
  42     unsigned int max_buf_size;
  43     /**
  44      * This array will contain at ith position the value of the best RLE code
  45      * if the line started at pixel i
  46      * There can be 3 values :
  47      * skip (0)     : skip as much as possible pixels because they are equal to the
  48      *                previous frame ones
  49      * repeat (<-1) : repeat that pixel -rle_code times, still as much as
  50      *                possible
  51      * copy (>0)    : copy the raw next rle_code pixels */
  52     signed char *rlecode_table;
  53     /**
  54      * This array will contain the length of the best rle encoding of the line
  55      * starting at ith pixel */
  56     int *length_table;
  57     /**
  58      * Will contain at ith position the number of consecutive pixels equal to the previous
  59      * frame starting from pixel i */
  60     uint8_t* skip_table;
  61 } QtrleEncContext;
  62
  63 static av_cold int qtrle_encode_init(AVCodecContext *avctx)
  64 {
  65     QtrleEncContext *s = avctx->priv_data;
  66
  67     if (av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
  68         return -1;
  69     }
  70     s->avctx=avctx;
  71
  72     switch (avctx->pix_fmt) {
  73     case AV_PIX_FMT_RGB555BE:
  74         s->pixel_size = 2;
  75         break;
  76     case AV_PIX_FMT_RGB24:
  77         s->pixel_size = 3;
  78         break;
  79     case AV_PIX_FMT_ARGB:
  80         s->pixel_size = 4;
  81         break;
  82     default:
  83         av_log(avctx, AV_LOG_ERROR, "Unsupported colorspace.\n");
  84         break;
  85     }
  86     avctx->bits_per_coded_sample = s->pixel_size*8;
  87
  88     s->rlecode_table = av_mallocz(s->avctx->width);
  89     s->skip_table    = av_mallocz(s->avctx->width);
  90     s->length_table  = av_mallocz((s->avctx->width + 1)*sizeof(int));
  91     if (!s->skip_table || !s->length_table || !s->rlecode_table) {
  92         av_log(avctx, AV_LOG_ERROR, "Error allocating memory.\n");
  93         return -1;
  94     }
  95     if (avpicture_alloc(&s->previous_frame, avctx->pix_fmt, avctx->width, avctx->height) < 0) {
  96         av_log(avctx, AV_LOG_ERROR, "Error allocating picture\n");
  97         return -1;
  98     }
  99
 100     s->max_buf_size = s->avctx->width*s->avctx->height*s->pixel_size*2 /* image base material */
 101                       + 15                                           /* header + footer */
 102                       + s->avctx->height*2                           /* skip code+rle end */
 103                       + s->avctx->width/MAX_RLE_BULK + 1             /* rle codes */;
 104     avctx->coded_frame = &s->frame;
 105     return 0;
 106 }
 107
 108 /**
 109  * Compute the best RLE sequence for a line
 110  */
 111 static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, uint8_t **buf)
 112 {
 113     int width=s->avctx->width;
 114     int i;
 115     signed char rlecode;
 116
 117     /* We will use it to compute the best bulk copy sequence */
 118     unsigned int bulkcount;
 119     /* This will be the number of pixels equal to the preivous frame one's
 120      * starting from the ith pixel */
 121     unsigned int skipcount;
 122     /* This will be the number of consecutive equal pixels in the current
 123      * frame, starting from the ith one also */
 124     unsigned int repeatcount;
 125
 126     /* The cost of the three different possibilities */
 127     int total_bulk_cost;
 128     int total_skip_cost;
 129     int total_repeat_cost;
 130
 131     int temp_cost;
 132     int j;
 133
 134     uint8_t *this_line = p->               data[0] + line*p->               linesize[0] +
 135         (width - 1)*s->pixel_size;
 136     uint8_t *prev_line = s->previous_frame.data[0] + line*s->previous_frame.linesize[0] +
 137         (width - 1)*s->pixel_size;
 138
 139     s->length_table[width] = 0;
 140     skipcount = 0;
 141
 142     for (i = width - 1; i >= 0; i--) {
 143
 144         if (!s->frame.key_frame && !memcmp(this_line, prev_line, s->pixel_size))
 145             skipcount = FFMIN(skipcount + 1, MAX_RLE_SKIP);
 146         else
 147             skipcount = 0;
 148
 149         total_skip_cost  = s->length_table[i + skipcount] + 2;
 150         s->skip_table[i] = skipcount;
 151
 152
 153         if (i < width - 1 && !memcmp(this_line, this_line + s->pixel_size, s->pixel_size))
 154             repeatcount = FFMIN(repeatcount + 1, MAX_RLE_REPEAT);
 155         else
 156             repeatcount = 1;
 157
 158         total_repeat_cost = s->length_table[i + repeatcount] + 1 + s->pixel_size;
 159
 160         /* skip code is free for the first pixel, it costs one byte for repeat and bulk copy
 161          * so let's make it aware */
 162         if (i == 0) {
 163             total_skip_cost--;
 164             total_repeat_cost++;
 165         }
 166
 167         if (repeatcount > 1 && (skipcount == 0 || total_repeat_cost < total_skip_cost)) {
 168             /* repeat is the best */
 169             s->length_table[i]  = total_repeat_cost;
 170             s->rlecode_table[i] = -repeatcount;
 171         }
 172         else if (skipcount > 0) {
 173             /* skip is the best choice here */
 174             s->length_table[i]  = total_skip_cost;
 175             s->rlecode_table[i] = 0;
 176         }
 177         else {
 178             /* We cannot do neither skip nor repeat
 179              * thus we search for the best bulk copy to do */
 180
 181             int limit = FFMIN(width - i, MAX_RLE_BULK);
 182
 183             temp_cost = 1 + s->pixel_size + !i;
 184             total_bulk_cost = INT_MAX;
 185
 186             for (j = 1; j <= limit; j++) {
 187                 if (s->length_table[i + j] + temp_cost < total_bulk_cost) {
 188                     /* We have found a better bulk copy ... */
 189                     total_bulk_cost = s->length_table[i + j] + temp_cost;
 190                     bulkcount = j;
 191                 }
 192                 temp_cost += s->pixel_size;
 193             }
 194
 195             s->length_table[i]  = total_bulk_cost;
 196             s->rlecode_table[i] = bulkcount;
 197         }
 198
 199         this_line -= s->pixel_size;
 200         prev_line -= s->pixel_size;
 201     }
 202
 203     /* Good ! Now we have the best sequence for this line, let's ouput it */
 204
 205     /* We do a special case for the first pixel so that we avoid testing it in
 206      * the whole loop */
 207
 208     i=0;
 209     this_line = p->               data[0] + line*p->linesize[0];
 210
 211     if (s->rlecode_table[0] == 0) {
 212         bytestream_put_byte(buf, s->skip_table[0] + 1);
 213         i += s->skip_table[0];
 214     }
 215     else bytestream_put_byte(buf, 1);
 216
 217
 218     while (i < width) {
 219         rlecode = s->rlecode_table[i];
 220         bytestream_put_byte(buf, rlecode);
 221         if (rlecode == 0) {
 222             /* Write a skip sequence */
 223             bytestream_put_byte(buf, s->skip_table[i] + 1);
 224             i += s->skip_table[i];
 225         }
 226         else if (rlecode > 0) {
 227             /* bulk copy */
 228             bytestream_put_buffer(buf, this_line + i*s->pixel_size, rlecode*s->pixel_size);
 229             i += rlecode;
 230         }
 231         else {
 232             /* repeat the bits */
 233             bytestream_put_buffer(buf, this_line + i*s->pixel_size, s->pixel_size);
 234             i -= rlecode;
 235         }
 236     }
 237     bytestream_put_byte(buf, -1); // end RLE line
 238 }
 239
 240 /** Encode frame including header */
 241 static int encode_frame(QtrleEncContext *s, const AVFrame *p, uint8_t *buf)
 242 {
 243     int i;
 244     int start_line = 0;
 245     int end_line = s->avctx->height;
 246     uint8_t *orig_buf = buf;
 247
 248     if (!s->frame.key_frame) {
 249         unsigned line_size = s->avctx->width * s->pixel_size;
 250         for (start_line = 0; start_line < s->avctx->height; start_line++)
 251             if (memcmp(p->data[0] + start_line*p->linesize[0],
 252                        s->previous_frame.data[0] + start_line*s->previous_frame.linesize[0],
 253                        line_size))
 254                 break;
 255
 256         for (end_line=s->avctx->height; end_line > start_line; end_line--)
 257             if (memcmp(p->data[0] + (end_line - 1)*p->linesize[0],
 258                        s->previous_frame.data[0] + (end_line - 1)*s->previous_frame.linesize[0],
 259                        line_size))
 260                 break;
 261     }
 262
 263     bytestream_put_be32(&buf, 0);                         // CHUNK SIZE, patched later
 264
 265     if ((start_line == 0 && end_line == s->avctx->height) || start_line == s->avctx->height)
 266         bytestream_put_be16(&buf, 0);                     // header
 267     else {
 268         bytestream_put_be16(&buf, 8);                     // header
 269         bytestream_put_be16(&buf, start_line);            // starting line
 270         bytestream_put_be16(&buf, 0);                     // unknown
 271         bytestream_put_be16(&buf, end_line - start_line); // lines to update
 272         bytestream_put_be16(&buf, 0);                     // unknown
 273     }
 274     for (i = start_line; i < end_line; i++)
 275         qtrle_encode_line(s, p, i, &buf);
 276
 277     bytestream_put_byte(&buf, 0);                         // zero skip code = frame finished
 278     AV_WB32(orig_buf, buf - orig_buf);                    // patch the chunk size
 279     return buf - orig_buf;
 280 }
 281
 282 static int qtrle_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
 283                               const AVFrame *pict, int *got_packet)
 284 {
 285     QtrleEncContext * const s = avctx->priv_data;
 286     AVFrame * const p = &s->frame;
 287     int ret;
 288
 289     *p = *pict;
 290
 291     if ((ret = ff_alloc_packet(pkt, s->max_buf_size)) < 0) {
 292         /* Upper bound check for compressed data */
 293         av_log(avctx, AV_LOG_ERROR, "Error getting output packet of size %d.\n", s->max_buf_size);
 294         return ret;
 295     }
 296
 297     if (avctx->gop_size == 0 || (s->avctx->frame_number % avctx->gop_size) == 0) {
 298         /* I-Frame */
 299         p->pict_type = AV_PICTURE_TYPE_I;
 300         p->key_frame = 1;
 301     } else {
 302         /* P-Frame */
 303         p->pict_type = AV_PICTURE_TYPE_P;
 304         p->key_frame = 0;
 305     }
 306
 307     pkt->size = encode_frame(s, pict, pkt->data);
 308
 309     /* save the current frame */
 310     av_picture_copy(&s->previous_frame, (AVPicture *)p, avctx->pix_fmt, avctx->width, avctx->height);
 311
 312     if (p->key_frame)
 313         pkt->flags |= AV_PKT_FLAG_KEY;
 314     *got_packet = 1;
 315
 316     return 0;
 317 }
 318
 319 static av_cold int qtrle_encode_end(AVCodecContext *avctx)
 320 {
 321     QtrleEncContext *s = avctx->priv_data;
 322
 323     avpicture_free(&s->previous_frame);
 324     av_free(s->rlecode_table);
 325     av_free(s->length_table);
 326     av_free(s->skip_table);
 327     return 0;
 328 }
 329
 330 AVCodec ff_qtrle_encoder = {
 331     .name           = "qtrle",
 332     .type           = AVMEDIA_TYPE_VIDEO,
 333     .id             = AV_CODEC_ID_QTRLE,
 334     .priv_data_size = sizeof(QtrleEncContext),
 335     .init           = qtrle_encode_init,
 336     .encode2        = qtrle_encode_frame,
 337     .close          = qtrle_encode_end,
 338     .pix_fmts       = (const enum AVPixelFormat[]){
 339         AV_PIX_FMT_RGB24, AV_PIX_FMT_RGB555BE, AV_PIX_FMT_ARGB, AV_PIX_FMT_NONE
 340     },
 341     .long_name      = NULL_IF_CONFIG_SMALL("QuickTime Animation (RLE) video"),
 342 };