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  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.     s->lzw = av_mallocz(ff_lzw_encode_state_size);
  220.     s->buf = av_malloc(avctx->width*avctx->height*2);
  221.     s->tmpl = av_malloc(avctx->width);
  222.     if (!s->tmpl || !s->buf || !s->lzw)
  223.         return AVERROR(ENOMEM);
  224.  
  225.     if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)
  226.         av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);
  227.  
  228.     return 0;
  229. }
  230.  
  231. static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
  232.                             const AVFrame *pict, int *got_packet)
  233. {
  234.     GIFContext *s = avctx->priv_data;
  235.     AVFrame *const p = (AVFrame *)pict;
  236.     uint8_t *outbuf_ptr, *end;
  237.     const uint32_t *palette = NULL;
  238.     int ret;
  239.  
  240.     if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + FF_MIN_BUFFER_SIZE)) < 0)
  241.         return ret;
  242.     outbuf_ptr = pkt->data;
  243.     end        = pkt->data + pkt->size;
  244.  
  245.     p->pict_type = AV_PICTURE_TYPE_I;
  246.     p->key_frame = 1;
  247.  
  248.     if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
  249.         uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
  250.         if (!pal_exdata)
  251.             return AVERROR(ENOMEM);
  252.         memcpy(pal_exdata, p->data[1], AVPALETTE_SIZE);
  253.         palette = (uint32_t*)p->data[1];
  254.     }
  255.  
  256.     gif_image_write_image(avctx, &outbuf_ptr, end, palette,
  257.                           pict->data[0], pict->linesize[0], pkt);
  258.     if (!s->last_frame) {
  259.         s->last_frame = av_frame_alloc();
  260.         if (!s->last_frame)
  261.             return AVERROR(ENOMEM);
  262.     }
  263.     av_frame_unref(s->last_frame);
  264.     ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
  265.     if (ret < 0)
  266.         return ret;
  267.  
  268.     pkt->size   = outbuf_ptr - pkt->data;
  269.     pkt->flags |= AV_PKT_FLAG_KEY;
  270.     *got_packet = 1;
  271.  
  272.     return 0;
  273. }
  274.  
  275. static int gif_encode_close(AVCodecContext *avctx)
  276. {
  277.     GIFContext *s = avctx->priv_data;
  278.  
  279.     av_freep(&s->lzw);
  280.     av_freep(&s->buf);
  281.     av_frame_free(&s->last_frame);
  282.     av_freep(&s->tmpl);
  283.     return 0;
  284. }
  285.  
  286. #define OFFSET(x) offsetof(GIFContext, x)
  287. #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
  288. static const AVOption gif_options[] = {
  289.     { "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },
  290.         { "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },
  291.         { "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" },
  292.     { NULL }
  293. };
  294.  
  295. static const AVClass gif_class = {
  296.     .class_name = "GIF encoder",
  297.     .item_name  = av_default_item_name,
  298.     .option     = gif_options,
  299.     .version    = LIBAVUTIL_VERSION_INT,
  300. };
  301.  
  302. AVCodec ff_gif_encoder = {
  303.     .name           = "gif",
  304.     .long_name      = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
  305.     .type           = AVMEDIA_TYPE_VIDEO,
  306.     .id             = AV_CODEC_ID_GIF,
  307.     .priv_data_size = sizeof(GIFContext),
  308.     .init           = gif_encode_init,
  309.     .encode2        = gif_encode_frame,
  310.     .close          = gif_encode_close,
  311.     .pix_fmts       = (const enum AVPixelFormat[]){
  312.         AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,
  313.         AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE
  314.     },
  315.     .priv_class     = &gif_class,
  316. };
  317.