summaryrefslogtreecommitdiff
path: root/libavcodec/gif.c
diff options
context:
space:
mode:
Diffstat (limited to 'libavcodec/gif.c')
-rw-r--r--libavcodec/gif.c309
1 files changed, 238 insertions, 71 deletions
diff --git a/libavcodec/gif.c b/libavcodec/gif.c
index 451e335991..6af1f4abe2 100644
--- a/libavcodec/gif.c
+++ b/libavcodec/gif.c
@@ -1,113 +1,202 @@
/*
- * GIF encoder.
* Copyright (c) 2000 Fabrice Bellard
* Copyright (c) 2002 Francois Revol
* Copyright (c) 2006 Baptiste Coudurier
*
* 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"
typedef struct GIFContext {
+ const AVClass *class;
LZWState *lzw;
uint8_t *buf;
+ int buf_size;
+ AVFrame *last_frame;
+ int flags;
+ uint32_t palette[AVPALETTE_COUNT]; ///< local reference palette for !pal8
+ int palette_loaded;
+ int transparent_index;
+ uint8_t *pal_exdata;
+ 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 pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)
{
- 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);
- }
+ int histogram[AVPALETTE_COUNT] = {0};
+ int x, y, i;
- return 0;
+ 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 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 len = 0, height = avctx->height, width = avctx->width, x, y;
+ int x_start = 0, y_start = 0, trans = s->transparent_index;
+ int honor_transparency = (s->flags & GF_TRANSDIFF) && s->last_frame;
const uint8_t *ptr;
+
+ /* 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 (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 (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);
+ }
+
/* 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);
+ }
+ }
+
+ 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");
+ } else {
+ uint8_t *pal_exdata = s->pal_exdata;
+ if (!pal_exdata)
+ pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
+ if (!pal_exdata)
+ return AVERROR(ENOMEM);
+ memcpy(pal_exdata, s->palette, AVPALETTE_SIZE);
+ pal_exdata[trans*4 + 3*!HAVE_BIGENDIAN] = 0x00;
+ }
+ }
+ if (trans < 0)
+ honor_transparency = 0;
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 +211,6 @@ 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;
}
@@ -130,6 +218,10 @@ static av_cold int gif_encode_init(AVCodecContext *avctx)
{
GIFContext *s = avctx->priv_data;
+ if (avctx->width > 65535 || avctx->height > 65535) {
+ av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n");
+ return AVERROR(EINVAL);
+ }
#if FF_API_CODED_FRAME
FF_DISABLE_DEPRECATION_WARNINGS
avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
@@ -137,31 +229,86 @@ FF_DISABLE_DEPRECATION_WARNINGS
FF_ENABLE_DEPRECATION_WARNINGS
#endif
+ 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 */
+/* FIXME: duplicated with lavc */
+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 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) {
+ uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
+ if (!pal_exdata)
+ return AVERROR(ENOMEM);
+ memcpy(pal_exdata, pict->data[1], AVPALETTE_SIZE);
+ palette = (uint32_t*)pict->data[1];
+
+ s->pal_exdata = pal_exdata;
+
+ /* The first palette with PAL8 will be used as generic palette by the
+ * muxer so we don't need to write it locally in the packet. We store
+ * it as a reference here in case it changes later. */
+ if (!s->palette_loaded) {
+ memcpy(s->palette, palette, AVPALETTE_SIZE);
+ s->transparent_index = get_palette_transparency_index(palette);
+ s->palette_loaded = 1;
+ palette = NULL;
+ } 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->last_frame = av_frame_alloc();
+ if (!s->last_frame)
+ return AVERROR(ENOMEM);
+ }
+ 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;
@@ -176,9 +323,28 @@ 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" },
+ { 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 +358,5 @@ 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,
};
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-02 23:18:52 +0000