ffmpeg/libavcodec/gif.c

   1 /*
   2  * Copyright (c) 2000 Fabrice Bellard
   3  * Copyright (c) 2002 Francois Revol
   4  * Copyright (c) 2006 Baptiste Coudurier
   5  *
   6  * first version by Francois Revol <revol@free.fr>
   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 /**
  26  * @file
  27  * GIF encoder
  28  * @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt
  29  */
  30
  31 #define BITSTREAM_WRITER_LE
  32 #include "libavutil/opt.h"
  33 #include "libavutil/imgutils.h"
  34 #include "avcodec.h"
  35 #include "bytestream.h"
  36 #include "internal.h"
  37 #include "lzw.h"
  38 #include "gif.h"
  39
  40 #include "put_bits.h"
  41
  42 typedef struct {
  43     const AVClass *class;
  44     LZWState *lzw;
  45     uint8_t *buf;
  46     AVFrame *last_frame;
  47     int flags;
  48     uint32_t palette[AVPALETTE_COUNT];  ///< local reference palette for !pal8
  49     uint8_t *tmpl;                      ///< temporary line buffer
  50 } GIFContext;
  51
  52 enum {
  53     GF_OFFSETTING = 1<<0,
  54     GF_TRANSDIFF  = 1<<1,
  55 };
  56
  57 static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)
  58 {
  59     int histogram[AVPALETTE_COUNT] = {0};
  60     int x, y, i;
  61
  62     for (y = 0; y < h; y++) {
  63         for (x = 0; x < w; x++)
  64             histogram[buf[x]]++;
  65         buf += linesize;
  66     }
  67     for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++)
  68         if (!histogram[i])
  69             return i;
  70     return -1;
  71 }
  72
  73 static int gif_image_write_image(AVCodecContext *avctx,
  74                                  uint8_t **bytestream, uint8_t *end,
  75                                  const uint32_t *palette,
  76                                  const uint8_t *buf, const int linesize,
  77                                  AVPacket *pkt)
  78 {
  79     GIFContext *s = avctx->priv_data;
  80     int len = 0, height = avctx->height, width = avctx->width, x, y;
  81     int x_start = 0, y_start = 0, trans = -1;
  82     const uint8_t *ptr;
  83
  84     /* Crop image */
  85     // TODO support with palette change
  86     if ((s->flags & GF_OFFSETTING) && s->last_frame && !palette) {
  87         const uint8_t *ref = s->last_frame->data[0];
  88         const int ref_linesize = s->last_frame->linesize[0];
  89         int x_end = avctx->width  - 1,
  90             y_end = avctx->height - 1;
  91
  92         /* skip common lines */
  93         while (y_start < y_end) {
  94             if (memcmp(ref + y_start*ref_linesize, buf + y_start*linesize, width))
  95                 break;
  96             y_start++;
  97         }
  98         while (y_end > y_start) {
  99             if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, width))
 100                 break;
 101             y_end--;
 102         }
 103         height = y_end + 1 - y_start;
 104
 105         /* skip common columns */
 106         while (x_start < x_end) {
 107             int same_column = 1;
 108             for (y = y_start; y < y_end; y++) {
 109                 if (ref[y*ref_linesize + x_start] != buf[y*linesize + x_start]) {
 110                     same_column = 0;
 111                     break;
 112                 }
 113             }
 114             if (!same_column)
 115                 break;
 116             x_start++;
 117         }
 118         while (x_end > x_start) {
 119             int same_column = 1;
 120             for (y = y_start; y < y_end; y++) {
 121                 if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) {
 122                     same_column = 0;
 123                     break;
 124                 }
 125             }
 126             if (!same_column)
 127                 break;
 128             x_end--;
 129         }
 130         width = x_end + 1 - x_start;
 131
 132         av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",
 133                width, height, x_start, y_start, avctx->width, avctx->height);
 134     }
 135
 136     /* image block */
 137     bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR);
 138     bytestream_put_le16(bytestream, x_start);
 139     bytestream_put_le16(bytestream, y_start);
 140     bytestream_put_le16(bytestream, width);
 141     bytestream_put_le16(bytestream, height);
 142
 143     if (!palette) {
 144         bytestream_put_byte(bytestream, 0x00); /* flags */
 145     } else {
 146         unsigned i;
 147         bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */
 148         for (i = 0; i < AVPALETTE_COUNT; i++) {
 149             const uint32_t v = palette[i];
 150             bytestream_put_be24(bytestream, v);
 151         }
 152     }
 153
 154     /* TODO: support with palette change (pal8) */
 155     if ((s->flags & GF_TRANSDIFF) && s->last_frame && !palette) {
 156         trans = pick_palette_entry(buf + y_start*linesize + x_start,
 157                                    linesize, width, height);
 158         if (trans < 0) { // TODO, patch welcome
 159             av_log(avctx, AV_LOG_DEBUG, "No available color, can not use transparency\n");
 160         } else {
 161             uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
 162             if (!pal_exdata)
 163                 return AVERROR(ENOMEM);
 164             memcpy(pal_exdata, s->palette, AVPALETTE_SIZE);
 165             pal_exdata[trans*4 + 3*!HAVE_BIGENDIAN] = 0x00;
 166         }
 167     }
 168
 169     bytestream_put_byte(bytestream, 0x08);
 170
 171     ff_lzw_encode_init(s->lzw, s->buf, 2 * width * height,
 172                        12, FF_LZW_GIF, put_bits);
 173
 174     ptr = buf + y_start*linesize + x_start;
 175     if (trans >= 0) {
 176         const int ref_linesize = s->last_frame->linesize[0];
 177         const uint8_t *ref = s->last_frame->data[0] + y_start*ref_linesize + x_start;
 178
 179         for (y = 0; y < height; y++) {
 180             memcpy(s->tmpl, ptr, width);
 181             for (x = 0; x < width; x++)
 182                 if (ref[x] == ptr[x])
 183                     s->tmpl[x] = trans;
 184             len += ff_lzw_encode(s->lzw, s->tmpl, width);
 185             ptr += linesize;
 186             ref += ref_linesize;
 187         }
 188     } else {
 189         for (y = 0; y < height; y++) {
 190             len += ff_lzw_encode(s->lzw, ptr, width);
 191             ptr += linesize;
 192         }
 193     }
 194     len += ff_lzw_encode_flush(s->lzw, flush_put_bits);
 195
 196     ptr = s->buf;
 197     while (len > 0) {
 198         int size = FFMIN(255, len);
 199         bytestream_put_byte(bytestream, size);
 200         if (end - *bytestream < size)
 201             return -1;
 202         bytestream_put_buffer(bytestream, ptr, size);
 203         ptr += size;
 204         len -= size;
 205     }
 206     bytestream_put_byte(bytestream, 0x00); /* end of image block */
 207     return 0;
 208 }
 209
 210 static av_cold int gif_encode_init(AVCodecContext *avctx)
 211 {
 212     GIFContext *s = avctx->priv_data;
 213
 214     if (avctx->width > 65535 || avctx->height > 65535) {
 215         av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n");
 216         return AVERROR(EINVAL);
 217     }
 218
 219     avctx->coded_frame = av_frame_alloc();
 220     if (!avctx->coded_frame)
 221         return AVERROR(ENOMEM);
 222
 223     avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
 224     avctx->coded_frame->key_frame = 1;
 225
 226     s->lzw = av_mallocz(ff_lzw_encode_state_size);
 227     s->buf = av_malloc(avctx->width*avctx->height*2);
 228     s->tmpl = av_malloc(avctx->width);
 229     if (!s->tmpl || !s->buf || !s->lzw)
 230         return AVERROR(ENOMEM);
 231
 232     if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)
 233         av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);
 234
 235     return 0;
 236 }
 237
 238 static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
 239                             const AVFrame *pict, int *got_packet)
 240 {
 241     GIFContext *s = avctx->priv_data;
 242     uint8_t *outbuf_ptr, *end;
 243     const uint32_t *palette = NULL;
 244     int ret;
 245
 246     if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + FF_MIN_BUFFER_SIZE)) < 0)
 247         return ret;
 248     outbuf_ptr = pkt->data;
 249     end        = pkt->data + pkt->size;
 250
 251     if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
 252         uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
 253         if (!pal_exdata)
 254             return AVERROR(ENOMEM);
 255         memcpy(pal_exdata, pict->data[1], AVPALETTE_SIZE);
 256         palette = (uint32_t*)pict->data[1];
 257     }
 258
 259     gif_image_write_image(avctx, &outbuf_ptr, end, palette,
 260                           pict->data[0], pict->linesize[0], pkt);
 261     if (!s->last_frame) {
 262         s->last_frame = av_frame_alloc();
 263         if (!s->last_frame)
 264             return AVERROR(ENOMEM);
 265     }
 266     av_frame_unref(s->last_frame);
 267     ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
 268     if (ret < 0)
 269         return ret;
 270
 271     pkt->size   = outbuf_ptr - pkt->data;
 272     pkt->flags |= AV_PKT_FLAG_KEY;
 273     *got_packet = 1;
 274
 275     return 0;
 276 }
 277
 278 static int gif_encode_close(AVCodecContext *avctx)
 279 {
 280     GIFContext *s = avctx->priv_data;
 281
 282     av_frame_free(&avctx->coded_frame);
 283
 284     av_freep(&s->lzw);
 285     av_freep(&s->buf);
 286     av_frame_free(&s->last_frame);
 287     av_freep(&s->tmpl);
 288     return 0;
 289 }
 290
 291 #define OFFSET(x) offsetof(GIFContext, x)
 292 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
 293 static const AVOption gif_options[] = {
 294     { "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },
 295         { "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },
 296         { "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" },
 297     { NULL }
 298 };
 299
 300 static const AVClass gif_class = {
 301     .class_name = "GIF encoder",
 302     .item_name  = av_default_item_name,
 303     .option     = gif_options,
 304     .version    = LIBAVUTIL_VERSION_INT,
 305 };
 306
 307 AVCodec ff_gif_encoder = {
 308     .name           = "gif",
 309     .long_name      = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
 310     .type           = AVMEDIA_TYPE_VIDEO,
 311     .id             = AV_CODEC_ID_GIF,
 312     .priv_data_size = sizeof(GIFContext),
 313     .init           = gif_encode_init,
 314     .encode2        = gif_encode_frame,
 315     .close          = gif_encode_close,
 316     .pix_fmts       = (const enum AVPixelFormat[]){
 317         AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,
 318         AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE
 319     },
 320     .priv_class     = &gif_class,
 321 };