diff options
Diffstat (limited to 'libavcodec/gif.c')
-rw-r--r-- | libavcodec/gif.c | 457 |
1 files changed, 381 insertions, 76 deletions
diff --git a/libavcodec/gif.c b/libavcodec/gif.c index 451e335991..9f2f30d863 100644 --- a/libavcodec/gif.c +++ b/libavcodec/gif.c @@ -1,113 +1,370 @@ /* - * GIF encoder. * Copyright (c) 2000 Fabrice Bellard * Copyright (c) 2002 Francois Revol * Copyright (c) 2006 Baptiste Coudurier + * Copyright (c) 2018 Bjorn Roche + * Copyright (c) 2018 Paul B Mahol * * first version by Francois Revol <revol@free.fr> * - * This file is part of Libav. + * This file is part of FFmpeg. * - * Libav is free software; you can redistribute it and/or + * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * - * Libav is distributed in the hope that it will be useful, + * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public - * License along with Libav; if not, write to the Free Software + * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ -/* - * Features and limitations: - * - currently no compression is performed, - * in fact the size of the data is 9/8 the size of the image in 8bpp - * - uses only a global standard palette - * - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS). - * - * Reference documents: - * http://www.goice.co.jp/member/mo/formats/gif.html - * http://astronomy.swin.edu.au/pbourke/dataformats/gif/ - * http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt - * - * this url claims to have an LZW algorithm not covered by Unisys patent: - * http://www.msg.net/utility/whirlgif/gifencod.html - * could help reduce the size of the files _a lot_... - * some sites mentions an RLE type compression also. +/** + * @file + * GIF encoder + * @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt */ +#define BITSTREAM_WRITER_LE +#include "libavutil/opt.h" +#include "libavutil/imgutils.h" #include "avcodec.h" #include "bytestream.h" #include "internal.h" #include "lzw.h" - -/* The GIF format uses reversed order for bitstreams... */ -/* at least they don't use PDP_ENDIAN :) */ -#define BITSTREAM_WRITER_LE +#include "gif.h" #include "put_bits.h" +#define DEFAULT_TRANSPARENCY_INDEX 0x1f + typedef struct GIFContext { + const AVClass *class; LZWState *lzw; uint8_t *buf; + int buf_size; + AVFrame *last_frame; + int flags; + int image; + uint32_t palette[AVPALETTE_COUNT]; ///< local reference palette for !pal8 + int palette_loaded; + int transparent_index; + uint8_t *tmpl; ///< temporary line buffer } GIFContext; -/* GIF header */ -static int gif_image_write_header(AVCodecContext *avctx, - uint8_t **bytestream, uint32_t *palette) +enum { + GF_OFFSETTING = 1<<0, + GF_TRANSDIFF = 1<<1, +}; + +static int is_image_translucent(AVCodecContext *avctx, + const uint8_t *buf, const int linesize) { - int i; - unsigned int v; - - bytestream_put_buffer(bytestream, "GIF", 3); - bytestream_put_buffer(bytestream, "89a", 3); - bytestream_put_le16(bytestream, avctx->width); - bytestream_put_le16(bytestream, avctx->height); - - bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */ - bytestream_put_byte(bytestream, 0x1f); /* background color index */ - bytestream_put_byte(bytestream, 0); /* aspect ratio */ - - /* the global palette */ - for(i=0;i<256;i++) { - v = palette[i]; - bytestream_put_be24(bytestream, v); + GIFContext *s = avctx->priv_data; + int trans = s->transparent_index; + + if (trans < 0) + return 0; + + for (int y = 0; y < avctx->height; y++) { + for (int x = 0; x < avctx->width; x++) { + if (buf[x] == trans) { + return 1; + } + } + buf += linesize; } return 0; } +static int get_palette_transparency_index(const uint32_t *palette) +{ + int transparent_color_index = -1; + unsigned i, smallest_alpha = 0xff; + + if (!palette) + return -1; + + for (i = 0; i < AVPALETTE_COUNT; i++) { + const uint32_t v = palette[i]; + if (v >> 24 < smallest_alpha) { + smallest_alpha = v >> 24; + transparent_color_index = i; + } + } + return smallest_alpha < 128 ? transparent_color_index : -1; +} + +static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h) +{ + int histogram[AVPALETTE_COUNT] = {0}; + int x, y, i; + + for (y = 0; y < h; y++) { + for (x = 0; x < w; x++) + histogram[buf[x]]++; + buf += linesize; + } + for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++) + if (!histogram[i]) + return i; + return -1; +} + +static void gif_crop_translucent(AVCodecContext *avctx, + const uint8_t *buf, const int linesize, + int *width, int *height, + int *x_start, int *y_start) +{ + GIFContext *s = avctx->priv_data; + int trans = s->transparent_index; + + /* Crop image */ + if ((s->flags & GF_OFFSETTING) && trans >= 0) { + const int w = avctx->width; + const int h = avctx->height; + int x_end = w - 1, + y_end = h - 1; + + // crop top + while (*y_start < y_end) { + int is_trans = 1; + for (int i = 0; i < w; i++) { + if (buf[w * *y_start + i] != trans) { + is_trans = 0; + break; + } + } + + if (!is_trans) + break; + (*y_start)++; + } + + // crop bottom + while (y_end < h) { + int is_trans = 1; + for (int i = 0; i < w; i++) { + if (buf[w * y_end + i] != trans) { + is_trans = 0; + break; + } + } + if (!is_trans) + break; + y_end--; + } + + // crop left + while (*x_start < x_end) { + int is_trans = 1; + for (int i = *y_start; i < y_end; i++) { + if (buf[w * i + *x_start] != trans) { + is_trans = 0; + break; + } + } + if (!is_trans) + break; + (*x_start)++; + } + + // crop right + while (x_end < w) { + int is_trans = 1; + for (int i = *y_start; i < y_end; i++) { + if (buf[w * i + x_end] != trans) { + is_trans = 0; + break; + } + } + if (!is_trans) + break; + x_end--; + } + + *height = y_end + 1 - *y_start; + *width = x_end + 1 - *x_start; + av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n", + *width, *height, *x_start, *y_start, avctx->width, avctx->height); + } +} + +static void gif_crop_opaque(AVCodecContext *avctx, + const uint32_t *palette, + const uint8_t *buf, const int linesize, + int *width, int *height, int *x_start, int *y_start) +{ + GIFContext *s = avctx->priv_data; + + /* Crop image */ + if ((s->flags & GF_OFFSETTING) && s->last_frame && !palette) { + const uint8_t *ref = s->last_frame->data[0]; + const int ref_linesize = s->last_frame->linesize[0]; + int x_end = avctx->width - 1, + y_end = avctx->height - 1; + + /* skip common lines */ + while (*y_start < y_end) { + if (memcmp(ref + *y_start*ref_linesize, buf + *y_start*linesize, *width)) + break; + (*y_start)++; + } + while (y_end > *y_start) { + if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, *width)) + break; + y_end--; + } + *height = y_end + 1 - *y_start; + + /* skip common columns */ + while (*x_start < x_end) { + int same_column = 1; + for (int y = *y_start; y <= y_end; y++) { + if (ref[y*ref_linesize + *x_start] != buf[y*linesize + *x_start]) { + same_column = 0; + break; + } + } + if (!same_column) + break; + (*x_start)++; + } + while (x_end > *x_start) { + int same_column = 1; + for (int y = *y_start; y <= y_end; y++) { + if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) { + same_column = 0; + break; + } + } + if (!same_column) + break; + x_end--; + } + *width = x_end + 1 - *x_start; + + av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n", + *width, *height, *x_start, *y_start, avctx->width, avctx->height); + } +} + static int gif_image_write_image(AVCodecContext *avctx, uint8_t **bytestream, uint8_t *end, - const uint8_t *buf, int linesize) + const uint32_t *palette, + const uint8_t *buf, const int linesize, + AVPacket *pkt) { GIFContext *s = avctx->priv_data; - int len = 0, height; + int disposal, len = 0, height = avctx->height, width = avctx->width, x, y; + int x_start = 0, y_start = 0, trans = s->transparent_index; + int bcid = -1, honor_transparency = (s->flags & GF_TRANSDIFF) && s->last_frame && !palette; const uint8_t *ptr; + + if (!s->image && avctx->frame_number && is_image_translucent(avctx, buf, linesize)) { + gif_crop_translucent(avctx, buf, linesize, &width, &height, &x_start, &y_start); + honor_transparency = 0; + disposal = GCE_DISPOSAL_BACKGROUND; + } else { + gif_crop_opaque(avctx, palette, buf, linesize, &width, &height, &x_start, &y_start); + disposal = GCE_DISPOSAL_INPLACE; + } + + if (s->image || !avctx->frame_number) { /* GIF header */ + const uint32_t *global_palette = palette ? palette : s->palette; + const AVRational sar = avctx->sample_aspect_ratio; + int64_t aspect = 0; + + if (sar.num > 0 && sar.den > 0) { + aspect = sar.num * 64LL / sar.den - 15; + if (aspect < 0 || aspect > 255) + aspect = 0; + } + + bytestream_put_buffer(bytestream, gif89a_sig, sizeof(gif89a_sig)); + bytestream_put_le16(bytestream, avctx->width); + bytestream_put_le16(bytestream, avctx->height); + + bcid = get_palette_transparency_index(global_palette); + + bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */ + bytestream_put_byte(bytestream, bcid < 0 ? DEFAULT_TRANSPARENCY_INDEX : bcid); /* background color index */ + bytestream_put_byte(bytestream, aspect); + for (int i = 0; i < 256; i++) { + const uint32_t v = global_palette[i] & 0xffffff; + bytestream_put_be24(bytestream, v); + } + } + + if (honor_transparency && trans < 0) { + trans = pick_palette_entry(buf + y_start*linesize + x_start, + linesize, width, height); + if (trans < 0) // TODO, patch welcome + av_log(avctx, AV_LOG_DEBUG, "No available color, can not use transparency\n"); + } + + if (trans < 0) + honor_transparency = 0; + + bcid = honor_transparency || disposal == GCE_DISPOSAL_BACKGROUND ? trans : get_palette_transparency_index(palette); + + /* graphic control extension */ + bytestream_put_byte(bytestream, GIF_EXTENSION_INTRODUCER); + bytestream_put_byte(bytestream, GIF_GCE_EXT_LABEL); + bytestream_put_byte(bytestream, 0x04); /* block size */ + bytestream_put_byte(bytestream, disposal<<2 | (bcid >= 0)); + bytestream_put_le16(bytestream, 5); // default delay + bytestream_put_byte(bytestream, bcid < 0 ? DEFAULT_TRANSPARENCY_INDEX : bcid); + bytestream_put_byte(bytestream, 0x00); + /* image block */ + bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR); + bytestream_put_le16(bytestream, x_start); + bytestream_put_le16(bytestream, y_start); + bytestream_put_le16(bytestream, width); + bytestream_put_le16(bytestream, height); - bytestream_put_byte(bytestream, 0x2c); - bytestream_put_le16(bytestream, 0); - bytestream_put_le16(bytestream, 0); - bytestream_put_le16(bytestream, avctx->width); - bytestream_put_le16(bytestream, avctx->height); - bytestream_put_byte(bytestream, 0x00); /* flags */ - /* no local clut */ + if (!palette) { + bytestream_put_byte(bytestream, 0x00); /* flags */ + } else { + unsigned i; + bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */ + for (i = 0; i < AVPALETTE_COUNT; i++) { + const uint32_t v = palette[i]; + bytestream_put_be24(bytestream, v); + } + } bytestream_put_byte(bytestream, 0x08); - ff_lzw_encode_init(s->lzw, s->buf, avctx->width*avctx->height, + ff_lzw_encode_init(s->lzw, s->buf, s->buf_size, 12, FF_LZW_GIF, put_bits); - ptr = buf; - for (height = avctx->height; height--;) { - len += ff_lzw_encode(s->lzw, ptr, avctx->width); - ptr += linesize; + ptr = buf + y_start*linesize + x_start; + if (honor_transparency) { + const int ref_linesize = s->last_frame->linesize[0]; + const uint8_t *ref = s->last_frame->data[0] + y_start*ref_linesize + x_start; + + for (y = 0; y < height; y++) { + memcpy(s->tmpl, ptr, width); + for (x = 0; x < width; x++) + if (ref[x] == ptr[x]) + s->tmpl[x] = trans; + len += ff_lzw_encode(s->lzw, s->tmpl, width); + ptr += linesize; + ref += ref_linesize; + } + } else { + for (y = 0; y < height; y++) { + len += ff_lzw_encode(s->lzw, ptr, width); + ptr += linesize; + } } len += ff_lzw_encode_flush(s->lzw, flush_put_bits); @@ -122,7 +379,6 @@ static int gif_image_write_image(AVCodecContext *avctx, len -= size; } bytestream_put_byte(bytestream, 0x00); /* end of image block */ - bytestream_put_byte(bytestream, 0x3b); return 0; } @@ -130,41 +386,69 @@ static av_cold int gif_encode_init(AVCodecContext *avctx) { GIFContext *s = avctx->priv_data; -#if FF_API_CODED_FRAME -FF_DISABLE_DEPRECATION_WARNINGS - avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I; - avctx->coded_frame->key_frame = 1; -FF_ENABLE_DEPRECATION_WARNINGS -#endif + if (avctx->width > 65535 || avctx->height > 65535) { + av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n"); + return AVERROR(EINVAL); + } + + s->transparent_index = -1; s->lzw = av_mallocz(ff_lzw_encode_state_size); - if (!s->lzw) + s->buf_size = avctx->width*avctx->height*2 + 1000; + s->buf = av_malloc(s->buf_size); + s->tmpl = av_malloc(avctx->width); + if (!s->tmpl || !s->buf || !s->lzw) return AVERROR(ENOMEM); - s->buf = av_malloc(avctx->width*avctx->height*2); - if (!s->buf) - return AVERROR(ENOMEM); + + if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0) + av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8); + return 0; } -/* better than nothing gif encoder */ static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFrame *pict, int *got_packet) { + GIFContext *s = avctx->priv_data; uint8_t *outbuf_ptr, *end; + const uint32_t *palette = NULL; int ret; - if ((ret = ff_alloc_packet(pkt, avctx->width*avctx->height*7/5 + AV_INPUT_BUFFER_MIN_SIZE)) < 0) { - av_log(avctx, AV_LOG_ERROR, "Error getting output packet.\n"); + if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + AV_INPUT_BUFFER_MIN_SIZE, 0)) < 0) return ret; - } outbuf_ptr = pkt->data; end = pkt->data + pkt->size; - gif_image_write_header(avctx, &outbuf_ptr, (uint32_t *)pict->data[1]); - gif_image_write_image(avctx, &outbuf_ptr, end, pict->data[0], pict->linesize[0]); + if (avctx->pix_fmt == AV_PIX_FMT_PAL8) { + palette = (uint32_t*)pict->data[1]; + + if (!s->palette_loaded) { + memcpy(s->palette, palette, AVPALETTE_SIZE); + s->transparent_index = get_palette_transparency_index(palette); + s->palette_loaded = 1; + } else if (!memcmp(s->palette, palette, AVPALETTE_SIZE)) { + palette = NULL; + } + } + + gif_image_write_image(avctx, &outbuf_ptr, end, palette, + pict->data[0], pict->linesize[0], pkt); + if (!s->last_frame && !s->image) { + s->last_frame = av_frame_alloc(); + if (!s->last_frame) + return AVERROR(ENOMEM); + } + + if (!s->image) { + av_frame_unref(s->last_frame); + ret = av_frame_ref(s->last_frame, (AVFrame*)pict); + if (ret < 0) + return ret; + } pkt->size = outbuf_ptr - pkt->data; - pkt->flags |= AV_PKT_FLAG_KEY; + if (s->image || !avctx->frame_number) + pkt->flags |= AV_PKT_FLAG_KEY; *got_packet = 1; return 0; @@ -176,9 +460,29 @@ static int gif_encode_close(AVCodecContext *avctx) av_freep(&s->lzw); av_freep(&s->buf); + s->buf_size = 0; + av_frame_free(&s->last_frame); + av_freep(&s->tmpl); return 0; } +#define OFFSET(x) offsetof(GIFContext, x) +#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM +static const AVOption gif_options[] = { + { "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" }, + { "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" }, + { "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" }, + { "gifimage", "enable encoding only images per frame", OFFSET(image), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS, "flags" }, + { NULL } +}; + +static const AVClass gif_class = { + .class_name = "GIF encoder", + .item_name = av_default_item_name, + .option = gif_options, + .version = LIBAVUTIL_VERSION_INT, +}; + AVCodec ff_gif_encoder = { .name = "gif", .long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"), @@ -192,4 +496,5 @@ AVCodec ff_gif_encoder = { AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE, AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE }, + .priv_class = &gif_class, }; |