* @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt
*/
+#include "libavutil/opt.h"
+#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#include "lzw.h"
+#include "gif.h"
-/* The GIF format uses reversed order for bitstreams... */
-/* at least they don't use PDP_ENDIAN :) */
#define BITSTREAM_WRITER_LE
-
#include "put_bits.h"
typedef struct {
+ const AVClass *class;
AVFrame picture;
LZWState *lzw;
uint8_t *buf;
AVFrame *last_frame;
+ int flags;
+ uint32_t palette[AVPALETTE_COUNT]; ///< local reference palette for !pal8
+ uint8_t *tmpl; ///< temporary line buffer
} GIFContext;
+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 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 int gif_image_write_image(AVCodecContext *avctx,
uint8_t **bytestream, uint8_t *end,
const uint32_t *palette,
- const uint8_t *buf, int linesize)
+ const uint8_t *buf, const int linesize,
+ AVPacket *pkt)
{
GIFContext *s = avctx->priv_data;
- int len = 0, height = avctx->height, width = avctx->width, y;
- int x_start = 0, y_start = 0;
+ int len = 0, height = avctx->height, width = avctx->width, x, y;
+ int x_start = 0, y_start = 0, trans = -1;
const uint8_t *ptr;
/* Crop image */
// TODO support with palette change
- if (s->last_frame && !palette) {
+ 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,
}
/* image block */
- bytestream_put_byte(bytestream, 0x2c);
+ bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR);
bytestream_put_le16(bytestream, x_start);
bytestream_put_le16(bytestream, y_start);
bytestream_put_le16(bytestream, width);
}
}
+ /* TODO: support with palette change (pal8) */
+ if ((s->flags & GF_TRANSDIFF) && s->last_frame && !palette) {
+ 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 = 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;
+ }
+ }
+
bytestream_put_byte(bytestream, 0x08);
ff_lzw_encode_init(s->lzw, s->buf, width * height,
12, FF_LZW_GIF, put_bits);
ptr = buf + y_start*linesize + x_start;
- for (y = 0; y < height; y++) {
- len += ff_lzw_encode(s->lzw, ptr, width);
- ptr += linesize;
+ if (trans >= 0) {
+ 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);
avctx->coded_frame = &s->picture;
s->lzw = av_mallocz(ff_lzw_encode_state_size);
s->buf = av_malloc(avctx->width*avctx->height*2);
- if (!s->buf || !s->lzw)
+ 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 */
static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
const AVFrame *pict, int *got_packet)
{
palette = (uint32_t*)p->data[1];
}
- gif_image_write_image(avctx, &outbuf_ptr, end, palette, pict->data[0], pict->linesize[0]);
+ 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)
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",
.type = AVMEDIA_TYPE_VIDEO,
AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE
},
.long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
+ .priv_class = &gif_class,
};
projects / ffmpeg / blobdiff