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lavc/gif: crop image when possible.

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Increase compression when pictures are similar.

-f lavfi testsrc=300: 61M -> 21M
This commit is contained in:
Clément Bœsch 2013-04-17 16:19:00 +02:00
parent 635389ccfa
commit e065e8a4ea
1 changed files with 73 additions and 9 deletions
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82
libavcodec/gif.c
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@ -49,6 +49,7 @@ typedef struct {
AVFrame picture;
LZWState *lzw;
uint8_t *buf;
AVFrame *last_frame;
} GIFContext;
static int gif_image_write_image(AVCodecContext *avctx,
@ -57,7 +58,8 @@ static int gif_image_write_image(AVCodecContext *avctx,
const uint8_t *buf, int linesize)
{
GIFContext *s = avctx->priv_data;
int len = 0, height;
int len = 0, height = avctx->height, width = avctx->width, y;
int x_start = 0, y_start = 0;
const uint8_t *ptr;
/* Mark one colour as transparent if the input palette contains at least
@ -82,12 +84,64 @@ static int gif_image_write_image(AVCodecContext *avctx,
}
}
/* Crop image */
// TODO support with palette change
if (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 < height) {
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 < width) {
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, 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_le16(bytestream, x_start);
bytestream_put_le16(bytestream, y_start);
bytestream_put_le16(bytestream, width);
bytestream_put_le16(bytestream, height);
if (!palette) {
bytestream_put_byte(bytestream, 0x00); /* flags */
@ -102,12 +156,12 @@ static int gif_image_write_image(AVCodecContext *avctx,
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, 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 = buf + y_start*linesize + x_start;
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);
@ -168,6 +222,15 @@ static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
palette = (uint32_t*)p->data[1];
gif_image_write_image(avctx, &outbuf_ptr, end, palette, pict->data[0], pict->linesize[0]);
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;
@ -182,6 +245,7 @@ static int gif_encode_close(AVCodecContext *avctx)
av_freep(&s->lzw);
av_freep(&s->buf);
av_frame_free(&s->last_frame);
return 0;
}