1 files changed, 236 insertions, 71 deletions

diff --git a/libavcodec/gif.c b/libavcodec/gif.c
index ae7fdfd818..cf5d438a72 100644
--- a/libavcodec/gif.c
+++ b/libavcodec/gif.c
@@ -1,113 +1,201 @@
 /*
- * 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;
+    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, 2 * width * height,
                        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 +210,6 @@ 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 +217,11 @@ 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);
+    }
+
     avctx->coded_frame = av_frame_alloc();
     if (!avctx->coded_frame)
         return AVERROR(ENOMEM);
@@ -137,31 +229,85 @@ static av_cold int gif_encode_init(AVCodecContext *avctx)
     avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
     avctx->coded_frame->key_frame = 1;
 
+    s->transparent_index = -1;
+
     s->lzw = av_mallocz(ff_lzw_encode_state_size);
-    if (!s->lzw)
-        return AVERROR(ENOMEM);
     s->buf = av_malloc(avctx->width*avctx->height*2);
-    if (!s->buf)
-         return AVERROR(ENOMEM);
+    s->tmpl = av_malloc(avctx->width);
+    if (!s->tmpl || !s->buf || !s->lzw)
+        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 + FF_MIN_BUFFER_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 + FF_MIN_BUFFER_SIZE)) < 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;
@@ -178,9 +324,27 @@ static int gif_encode_close(AVCodecContext *avctx)
 
     av_freep(&s->lzw);
     av_freep(&s->buf);
+    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)"),
@@ -194,4 +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,
 };