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