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     int pixel_size;
  40     AVPicture previous_frame;
  41     unsigned int max_buf_size;
  42     /**
  43      * This array will contain at ith position the value of the best RLE code
  44      * if the line started at pixel i
  45      * There can be 3 values :
  46      * skip (0)     : skip as much as possible pixels because they are equal to the
  47      *                previous frame ones
  48      * repeat (<-1) : repeat that pixel -rle_code times, still as much as
  49      *                possible
  50      * copy (>0)    : copy the raw next rle_code pixels */
  51     signed char *rlecode_table;
  52     /**
  53      * This array will contain the length of the best rle encoding of the line
  54      * starting at ith pixel */
  55     int *length_table;
  56     /**
  57      * Will contain at ith position the number of consecutive pixels equal to the previous
  58      * frame starting from pixel i */
  59     uint8_t* skip_table;
  60
  61     /** Encoded frame is a key frame */
  62     int key_frame;
  63 } QtrleEncContext;
  64
  65 static av_cold int qtrle_encode_end(AVCodecContext *avctx)
  66 {
  67     QtrleEncContext *s = avctx->priv_data;
  68
  69     avpicture_free(&s->previous_frame);
  70     av_free(s->rlecode_table);
  71     av_free(s->length_table);
  72     av_free(s->skip_table);
  73     return 0;
  74 }
  75
  76 static av_cold int qtrle_encode_init(AVCodecContext *avctx)
  77 {
  78     QtrleEncContext *s = avctx->priv_data;
  79
  80     if (av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
  81         return -1;
  82     }
  83     s->avctx=avctx;
  84
  85     switch (avctx->pix_fmt) {
  86     case AV_PIX_FMT_RGB555BE:
  87         s->pixel_size = 2;
  88         break;
  89     case AV_PIX_FMT_RGB24:
  90         s->pixel_size = 3;
  91         break;
  92     case AV_PIX_FMT_ARGB:
  93         s->pixel_size = 4;
  94         break;
  95     default:
  96         av_log(avctx, AV_LOG_ERROR, "Unsupported colorspace.\n");
  97         break;
  98     }
  99     avctx->bits_per_coded_sample = s->pixel_size*8;
 100
 101     s->rlecode_table = av_mallocz(s->avctx->width);
 102     s->skip_table    = av_mallocz(s->avctx->width);
 103     s->length_table  = av_mallocz((s->avctx->width + 1)*sizeof(int));
 104     if (!s->skip_table || !s->length_table || !s->rlecode_table) {
 105         av_log(avctx, AV_LOG_ERROR, "Error allocating memory.\n");
 106         return -1;
 107     }
 108     if (avpicture_alloc(&s->previous_frame, avctx->pix_fmt, avctx->width, avctx->height) < 0) {
 109         av_log(avctx, AV_LOG_ERROR, "Error allocating picture\n");
 110         return -1;
 111     }
 112
 113     s->max_buf_size = s->avctx->width*s->avctx->height*s->pixel_size*2 /* image base material */
 114                       + 15                                           /* header + footer */
 115                       + s->avctx->height*2                           /* skip code+rle end */
 116                       + s->avctx->width/MAX_RLE_BULK + 1             /* rle codes */;
 117
 118     return 0;
 119 }
 120
 121 /**
 122  * Compute the best RLE sequence for a line
 123  */
 124 static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, uint8_t **buf)
 125 {
 126     int width=s->avctx->width;
 127     int i;
 128     signed char rlecode;
 129
 130     /* We will use it to compute the best bulk copy sequence */
 131     unsigned int bulkcount;
 132     /* This will be the number of pixels equal to the preivous frame one's
 133      * starting from the ith pixel */
 134     unsigned int skipcount;
 135     /* This will be the number of consecutive equal pixels in the current
 136      * frame, starting from the ith one also */
 137     unsigned int repeatcount;
 138
 139     /* The cost of the three different possibilities */
 140     int total_bulk_cost;
 141     int total_skip_cost;
 142     int total_repeat_cost;
 143
 144     int temp_cost;
 145     int j;
 146
 147     uint8_t *this_line = p->               data[0] + line*p->               linesize[0] +
 148         (width - 1)*s->pixel_size;
 149     uint8_t *prev_line = s->previous_frame.data[0] + line*s->previous_frame.linesize[0] +
 150         (width - 1)*s->pixel_size;
 151
 152     s->length_table[width] = 0;
 153     skipcount = 0;
 154
 155     for (i = width - 1; i >= 0; i--) {
 156
 157         if (!s->key_frame && !memcmp(this_line, prev_line, s->pixel_size))
 158             skipcount = FFMIN(skipcount + 1, MAX_RLE_SKIP);
 159         else
 160             skipcount = 0;
 161
 162         total_skip_cost  = s->length_table[i + skipcount] + 2;
 163         s->skip_table[i] = skipcount;
 164
 165
 166         if (i < width - 1 && !memcmp(this_line, this_line + s->pixel_size, s->pixel_size))
 167             repeatcount = FFMIN(repeatcount + 1, MAX_RLE_REPEAT);
 168         else
 169             repeatcount = 1;
 170
 171         total_repeat_cost = s->length_table[i + repeatcount] + 1 + s->pixel_size;
 172
 173         /* skip code is free for the first pixel, it costs one byte for repeat and bulk copy
 174          * so let's make it aware */
 175         if (i == 0) {
 176             total_skip_cost--;
 177             total_repeat_cost++;
 178         }
 179
 180         if (repeatcount > 1 && (skipcount == 0 || total_repeat_cost < total_skip_cost)) {
 181             /* repeat is the best */
 182             s->length_table[i]  = total_repeat_cost;
 183             s->rlecode_table[i] = -repeatcount;
 184         }
 185         else if (skipcount > 0) {
 186             /* skip is the best choice here */
 187             s->length_table[i]  = total_skip_cost;
 188             s->rlecode_table[i] = 0;
 189         }
 190         else {
 191             /* We cannot do neither skip nor repeat
 192              * thus we search for the best bulk copy to do */
 193
 194             int limit = FFMIN(width - i, MAX_RLE_BULK);
 195
 196             temp_cost = 1 + s->pixel_size + !i;
 197             total_bulk_cost = INT_MAX;
 198
 199             for (j = 1; j <= limit; j++) {
 200                 if (s->length_table[i + j] + temp_cost < total_bulk_cost) {
 201                     /* We have found a better bulk copy ... */
 202                     total_bulk_cost = s->length_table[i + j] + temp_cost;
 203                     bulkcount = j;
 204                 }
 205                 temp_cost += s->pixel_size;
 206             }
 207
 208             s->length_table[i]  = total_bulk_cost;
 209             s->rlecode_table[i] = bulkcount;
 210         }
 211
 212         this_line -= s->pixel_size;
 213         prev_line -= s->pixel_size;
 214     }
 215
 216     /* Good ! Now we have the best sequence for this line, let's ouput it */
 217
 218     /* We do a special case for the first pixel so that we avoid testing it in
 219      * the whole loop */
 220
 221     i=0;
 222     this_line = p->               data[0] + line*p->linesize[0];
 223
 224     if (s->rlecode_table[0] == 0) {
 225         bytestream_put_byte(buf, s->skip_table[0] + 1);
 226         i += s->skip_table[0];
 227     }
 228     else bytestream_put_byte(buf, 1);
 229
 230
 231     while (i < width) {
 232         rlecode = s->rlecode_table[i];
 233         bytestream_put_byte(buf, rlecode);
 234         if (rlecode == 0) {
 235             /* Write a skip sequence */
 236             bytestream_put_byte(buf, s->skip_table[i] + 1);
 237             i += s->skip_table[i];
 238         }
 239         else if (rlecode > 0) {
 240             /* bulk copy */
 241             bytestream_put_buffer(buf, this_line + i*s->pixel_size, rlecode*s->pixel_size);
 242             i += rlecode;
 243         }
 244         else {
 245             /* repeat the bits */
 246             bytestream_put_buffer(buf, this_line + i*s->pixel_size, s->pixel_size);
 247             i -= rlecode;
 248         }
 249     }
 250     bytestream_put_byte(buf, -1); // end RLE line
 251 }
 252
 253 /** Encode frame including header */
 254 static int encode_frame(QtrleEncContext *s, const AVFrame *p, uint8_t *buf)
 255 {
 256     int i;
 257     int start_line = 0;
 258     int end_line = s->avctx->height;
 259     uint8_t *orig_buf = buf;
 260
 261     if (!s->key_frame) {
 262         unsigned line_size = s->avctx->width * s->pixel_size;
 263         for (start_line = 0; start_line < s->avctx->height; start_line++)
 264             if (memcmp(p->data[0] + start_line*p->linesize[0],
 265                        s->previous_frame.data[0] + start_line*s->previous_frame.linesize[0],
 266                        line_size))
 267                 break;
 268
 269         for (end_line=s->avctx->height; end_line > start_line; end_line--)
 270             if (memcmp(p->data[0] + (end_line - 1)*p->linesize[0],
 271                        s->previous_frame.data[0] + (end_line - 1)*s->previous_frame.linesize[0],
 272                        line_size))
 273                 break;
 274     }
 275
 276     bytestream_put_be32(&buf, 0);                         // CHUNK SIZE, patched later
 277
 278     if ((start_line == 0 && end_line == s->avctx->height) || start_line == s->avctx->height)
 279         bytestream_put_be16(&buf, 0);                     // header
 280     else {
 281         bytestream_put_be16(&buf, 8);                     // header
 282         bytestream_put_be16(&buf, start_line);            // starting line
 283         bytestream_put_be16(&buf, 0);                     // unknown
 284         bytestream_put_be16(&buf, end_line - start_line); // lines to update
 285         bytestream_put_be16(&buf, 0);                     // unknown
 286     }
 287     for (i = start_line; i < end_line; i++)
 288         qtrle_encode_line(s, p, i, &buf);
 289
 290     bytestream_put_byte(&buf, 0);                         // zero skip code = frame finished
 291     AV_WB32(orig_buf, buf - orig_buf);                    // patch the chunk size
 292     return buf - orig_buf;
 293 }
 294
 295 static int qtrle_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
 296                               const AVFrame *pict, int *got_packet)
 297 {
 298     QtrleEncContext * const s = avctx->priv_data;
 299     enum AVPictureType pict_type;
 300     int ret;
 301
 302     if ((ret = ff_alloc_packet(pkt, s->max_buf_size)) < 0) {
 303         /* Upper bound check for compressed data */
 304         av_log(avctx, AV_LOG_ERROR, "Error getting output packet of size %d.\n", s->max_buf_size);
 305         return ret;
 306     }
 307
 308     if (avctx->gop_size == 0 || (s->avctx->frame_number % avctx->gop_size) == 0) {
 309         /* I-Frame */
 310         pict_type = AV_PICTURE_TYPE_I;
 311         s->key_frame = 1;
 312     } else {
 313         /* P-Frame */
 314         pict_type = AV_PICTURE_TYPE_P;
 315         s->key_frame = 0;
 316     }
 317
 318     pkt->size = encode_frame(s, pict, pkt->data);
 319
 320     /* save the current frame */
 321     av_picture_copy(&s->previous_frame, (const AVPicture *)pict,
 322                     avctx->pix_fmt, avctx->width, avctx->height);
 323
 324 #if FF_API_CODED_FRAME
 325 FF_DISABLE_DEPRECATION_WARNINGS
 326     avctx->coded_frame->key_frame = s->key_frame;
 327     avctx->coded_frame->pict_type = pict_type;
 328 FF_ENABLE_DEPRECATION_WARNINGS
 329 #endif
 330
 331     if (s->key_frame)
 332         pkt->flags |= AV_PKT_FLAG_KEY;
 333     *got_packet = 1;
 334
 335     return 0;
 336 }
 337
 338 AVCodec ff_qtrle_encoder = {
 339     .name           = "qtrle",
 340     .long_name      = NULL_IF_CONFIG_SMALL("QuickTime Animation (RLE) video"),
 341     .type           = AVMEDIA_TYPE_VIDEO,
 342     .id             = AV_CODEC_ID_QTRLE,
 343     .priv_data_size = sizeof(QtrleEncContext),
 344     .init           = qtrle_encode_init,
 345     .encode2        = qtrle_encode_frame,
 346     .close          = qtrle_encode_end,
 347     .pix_fmts       = (const enum AVPixelFormat[]){
 348         AV_PIX_FMT_RGB24, AV_PIX_FMT_RGB555BE, AV_PIX_FMT_ARGB, AV_PIX_FMT_NONE
 349     },
 350 };