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 FFmpeg.
   9  *
  10  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 #include "avcodec.h"
  26 #include "bytestream.h"
  27
  28 /** Maximum RLE code for bulk copy */
  29 #define MAX_RLE_BULK   127
  30 /** Maximum RLE code for repeat */
  31 #define MAX_RLE_REPEAT 128
  32 /** Maximum RLE code for skip */
  33 #define MAX_RLE_SKIP   254
  34
  35 typedef struct QtrleEncContext {
  36     AVCodecContext *avctx;
  37     AVFrame frame;
  38     int pixel_size;
  39     AVPicture previous_frame;
  40     unsigned int max_buf_size;
  41     /**
  42      * This array will contain at ith position the value of the best RLE code
  43      * if the line started at pixel i
  44      * There can be 3 values :
  45      * skip (0)     : skip as much as possible pixels because they are equal to the
  46      *                previous frame ones
  47      * repeat (<-1) : repeat that pixel -rle_code times, still as much as
  48      *                possible
  49      * copy (>0)    : copy the raw next rle_code pixels */
  50     signed char *rlecode_table;
  51     /**
  52      * This array will contain the length of the best rle encoding of the line
  53      * starting at ith pixel */
  54     int *length_table;
  55     /**
  56      * Will contain at ith position the number of consecutive pixels equal to the previous
  57      * frame starting from pixel i */
  58     uint8_t* skip_table;
  59 } QtrleEncContext;
  60
  61 static av_cold int qtrle_encode_init(AVCodecContext *avctx)
  62 {
  63     QtrleEncContext *s = avctx->priv_data;
  64
  65     if (avcodec_check_dimensions(avctx, avctx->width, avctx->height) < 0) {
  66         return -1;
  67     }
  68     s->avctx=avctx;
  69
  70     switch (avctx->pix_fmt) {
  71 /*    case PIX_FMT_RGB555:
  72         s->pixel_size = 2;
  73         break;*/
  74     case PIX_FMT_RGB24:
  75         s->pixel_size = 3;
  76         break;
  77     case PIX_FMT_ARGB:
  78         s->pixel_size = 4;
  79         break;
  80     default:
  81         av_log(avctx, AV_LOG_ERROR, "Unsupported colorspace.\n");
  82         break;
  83     }
  84     avctx->bits_per_coded_sample = s->pixel_size*8;
  85
  86     s->rlecode_table = av_mallocz(s->avctx->width);
  87     s->skip_table    = av_mallocz(s->avctx->width);
  88     s->length_table  = av_mallocz((s->avctx->width + 1)*sizeof(int));
  89     if (!s->skip_table || !s->length_table || !s->rlecode_table) {
  90         av_log(avctx, AV_LOG_ERROR, "Error allocating memory.\n");
  91         return -1;
  92     }
  93     if (avpicture_alloc(&s->previous_frame, avctx->pix_fmt, avctx->width, avctx->height) < 0) {
  94         av_log(avctx, AV_LOG_ERROR, "Error allocating picture\n");
  95         return -1;
  96     }
  97
  98     s->max_buf_size = s->avctx->width*s->avctx->height*s->pixel_size /* image base material */
  99                       + 15                                           /* header + footer */
 100                       + s->avctx->height*2                           /* skip code+rle end */
 101                       + s->avctx->width/MAX_RLE_BULK + 1             /* rle codes */;
 102     avctx->coded_frame = &s->frame;
 103     return 0;
 104 }
 105
 106 /**
 107  * Computes the best RLE sequence for a line
 108  */
 109 static void qtrle_encode_line(QtrleEncContext *s, AVFrame *p, int line, uint8_t **buf)
 110 {
 111     int width=s->avctx->width;
 112     int i;
 113     signed char rlecode;
 114
 115     /* We will use it to compute the best bulk copy sequence */
 116     unsigned int bulkcount;
 117     /* This will be the number of pixels equal to the preivous frame one's
 118      * starting from the ith pixel */
 119     unsigned int skipcount;
 120     /* This will be the number of consecutive equal pixels in the current
 121      * frame, starting from the ith one also */
 122     unsigned int av_uninit(repeatcount);
 123
 124     /* The cost of the three different possibilities */
 125     int total_bulk_cost;
 126     int total_skip_cost;
 127     int total_repeat_cost;
 128
 129     int temp_cost;
 130     int j;
 131
 132     uint8_t *this_line = p->               data[0] + line*p->               linesize[0] +
 133         (width - 1)*s->pixel_size;
 134     uint8_t *prev_line = s->previous_frame.data[0] + line*s->previous_frame.linesize[0] +
 135         (width - 1)*s->pixel_size;
 136
 137     s->length_table[width] = 0;
 138     skipcount = 0;
 139
 140     for (i = width - 1; i >= 0; i--) {
 141
 142         if (!s->frame.key_frame && !memcmp(this_line, prev_line, s->pixel_size))
 143             skipcount = FFMIN(skipcount + 1, MAX_RLE_SKIP);
 144         else
 145             skipcount = 0;
 146
 147         total_skip_cost  = s->length_table[i + skipcount] + 2;
 148         s->skip_table[i] = skipcount;
 149
 150
 151         if (i < width - 1 && !memcmp(this_line, this_line + s->pixel_size, s->pixel_size))
 152             repeatcount = FFMIN(repeatcount + 1, MAX_RLE_REPEAT);
 153         else
 154             repeatcount = 1;
 155
 156         total_repeat_cost = s->length_table[i + repeatcount] + 1 + s->pixel_size;
 157
 158         /* skip code is free for the first pixel, it costs one byte for repeat and bulk copy
 159          * so let's make it aware */
 160         if (i == 0) {
 161             total_skip_cost--;
 162             total_repeat_cost++;
 163         }
 164
 165         if (repeatcount > 1 && (skipcount == 0 || total_repeat_cost < total_skip_cost)) {
 166             /* repeat is the best */
 167             s->length_table[i]  = total_repeat_cost;
 168             s->rlecode_table[i] = -repeatcount;
 169         }
 170         else if (skipcount > 0) {
 171             /* skip is the best choice here */
 172             s->length_table[i]  = total_skip_cost;
 173             s->rlecode_table[i] = 0;
 174         }
 175         else {
 176             /* We cannot do neither skip nor repeat
 177              * thus we search for the best bulk copy to do */
 178
 179             int limit = FFMIN(width - i, MAX_RLE_BULK);
 180
 181             temp_cost = 1 + s->pixel_size + !i;
 182             total_bulk_cost = INT_MAX;
 183
 184             for (j = 1; j <= limit; j++) {
 185                 if (s->length_table[i + j] + temp_cost < total_bulk_cost) {
 186                     /* We have found a better bulk copy ... */
 187                     total_bulk_cost = s->length_table[i + j] + temp_cost;
 188                     bulkcount = j;
 189                 }
 190                 temp_cost += s->pixel_size;
 191             }
 192
 193             s->length_table[i]  = total_bulk_cost;
 194             s->rlecode_table[i] = bulkcount;
 195         }
 196
 197         this_line -= s->pixel_size;
 198         prev_line -= s->pixel_size;
 199     }
 200
 201     /* Good ! Now we have the best sequence for this line, let's ouput it */
 202
 203     /* We do a special case for the first pixel so that we avoid testing it in
 204      * the whole loop */
 205
 206     i=0;
 207     this_line = p->               data[0] + line*p->linesize[0];
 208
 209     if (s->rlecode_table[0] == 0) {
 210         bytestream_put_byte(buf, s->skip_table[0] + 1);
 211         i += s->skip_table[0];
 212     }
 213     else bytestream_put_byte(buf, 1);
 214
 215
 216     while (i < width) {
 217         rlecode = s->rlecode_table[i];
 218         bytestream_put_byte(buf, rlecode);
 219         if (rlecode == 0) {
 220             /* Write a skip sequence */
 221             bytestream_put_byte(buf, s->skip_table[i] + 1);
 222             i += s->skip_table[i];
 223         }
 224         else if (rlecode > 0) {
 225             /* bulk copy */
 226             bytestream_put_buffer(buf, this_line + i*s->pixel_size, rlecode*s->pixel_size);
 227             i += rlecode;
 228         }
 229         else {
 230             /* repeat the bits */
 231             bytestream_put_buffer(buf, this_line + i*s->pixel_size, s->pixel_size);
 232             i -= rlecode;
 233         }
 234     }
 235     bytestream_put_byte(buf, -1); // end RLE line
 236 }
 237
 238 /** Encodes frame including header */
 239 static int encode_frame(QtrleEncContext *s, AVFrame *p, uint8_t *buf)
 240 {
 241     int i;
 242     int start_line = 0;
 243     int end_line = s->avctx->height;
 244     uint8_t *orig_buf = buf;
 245
 246     if (!s->frame.key_frame) {
 247         unsigned line_size = s->avctx->width * s->pixel_size;
 248         for (start_line = 0; start_line < s->avctx->height; start_line++)
 249             if (memcmp(p->data[0] + start_line*p->linesize[0],
 250                        s->previous_frame.data[0] + start_line*s->previous_frame.linesize[0],
 251                        line_size))
 252                 break;
 253
 254         for (end_line=s->avctx->height; end_line > start_line; end_line--)
 255             if (memcmp(p->data[0] + (end_line - 1)*p->linesize[0],
 256                        s->previous_frame.data[0] + (end_line - 1)*s->previous_frame.linesize[0],
 257                        line_size))
 258                 break;
 259     }
 260
 261     bytestream_put_be32(&buf, 0);                         // CHUNK SIZE, patched later
 262
 263     if ((start_line == 0 && end_line == s->avctx->height) || start_line == s->avctx->height)
 264         bytestream_put_be16(&buf, 0);                     // header
 265     else {
 266         bytestream_put_be16(&buf, 8);                     // header
 267         bytestream_put_be16(&buf, start_line);            // starting line
 268         bytestream_put_be16(&buf, 0);                     // unknown
 269         bytestream_put_be16(&buf, end_line - start_line); // lines to update
 270         bytestream_put_be16(&buf, 0);                     // unknown
 271     }
 272     for (i = start_line; i < end_line; i++)
 273         qtrle_encode_line(s, p, i, &buf);
 274
 275     bytestream_put_byte(&buf, 0);                         // zero skip code = frame finished
 276     AV_WB32(orig_buf, buf - orig_buf);                    // patch the chunk size
 277     return buf - orig_buf;
 278 }
 279
 280 static int qtrle_encode_frame(AVCodecContext *avctx, uint8_t *buf, int buf_size, void *data)
 281 {
 282     QtrleEncContext * const s = avctx->priv_data;
 283     AVFrame *pict = data;
 284     AVFrame * const p = &s->frame;
 285     int chunksize;
 286
 287     *p = *pict;
 288
 289     if (buf_size < s->max_buf_size) {
 290         /* Upper bound check for compressed data */
 291         av_log(avctx, AV_LOG_ERROR, "buf_size %d <  %d\n", buf_size, s->max_buf_size);
 292         return -1;
 293     }
 294
 295     if (avctx->gop_size == 0 || (s->avctx->frame_number % avctx->gop_size) == 0) {
 296         /* I-Frame */
 297         p->pict_type = FF_I_TYPE;
 298         p->key_frame = 1;
 299     } else {
 300         /* P-Frame */
 301         p->pict_type = FF_P_TYPE;
 302         p->key_frame = 0;
 303     }
 304
 305     chunksize = encode_frame(s, pict, buf);
 306
 307     /* save the current frame */
 308     av_picture_copy(&s->previous_frame, (AVPicture *)p, avctx->pix_fmt, avctx->width, avctx->height);
 309     return chunksize;
 310 }
 311
 312 static av_cold int qtrle_encode_end(AVCodecContext *avctx)
 313 {
 314     QtrleEncContext *s = avctx->priv_data;
 315
 316     avpicture_free(&s->previous_frame);
 317     av_free(s->rlecode_table);
 318     av_free(s->length_table);
 319     av_free(s->skip_table);
 320     return 0;
 321 }
 322
 323 AVCodec qtrle_encoder = {
 324     "qtrle",
 325     CODEC_TYPE_VIDEO,
 326     CODEC_ID_QTRLE,
 327     sizeof(QtrleEncContext),
 328     qtrle_encode_init,
 329     qtrle_encode_frame,
 330     qtrle_encode_end,
 331     .pix_fmts = (enum PixelFormat[]){PIX_FMT_RGB24, PIX_FMT_ARGB, PIX_FMT_NONE},
 332     .long_name = NULL_IF_CONFIG_SMALL("QuickTime Animation (RLE) video"),
 333 };