From e1b35bdde2fc84de0435a1ab2d085452a0d5ad00 Mon Sep 17 00:00:00 2001 From: Clément Bœsch Date: Fri, 19 Apr 2013 19:01:37 +0200 Subject: lavc/gif: add flag to enable transparency detection between frames. While this is not always optimal, in practice most of the common cases are. ffmpeg -i big_buck_bunny_1080p_h264.mov -ss 45 -vf scale=320:160 -gifflags -transdiff -frames:v 50 -y bbb-notrans.gif ffmpeg -i big_buck_bunny_1080p_h264.mov -ss 45 -vf scale=320:160 -gifflags +transdiff -frames:v 50 -y bbb-trans.gif -rw-r--r-- 1 ubitux ubitux 1.1M Apr 19 19:00 bbb-notrans.gif -rw-r--r-- 1 ubitux ubitux 378K Apr 19 19:00 bbb-trans.gif --- libavcodec/gif.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 66 insertions(+), 6 deletions(-) (limited to 'libavcodec/gif.c') diff --git a/libavcodec/gif.c b/libavcodec/gif.c index c17a23f920..1dcb676869 100644 --- a/libavcodec/gif.c +++ b/libavcodec/gif.c @@ -29,6 +29,7 @@ */ #include "libavutil/opt.h" +#include "libavutil/imgutils.h" #include "avcodec.h" #include "bytestream.h" #include "internal.h" @@ -47,20 +48,40 @@ typedef struct { 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 */ @@ -133,16 +154,47 @@ static int gif_image_write_image(AVCodecContext *avctx, } } + /* 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] = 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; + 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 { + /* TODO: reindent */ 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); ptr = s->buf; @@ -171,8 +223,13 @@ static av_cold int gif_encode_init(AVCodecContext *avctx) 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; } @@ -203,7 +260,8 @@ 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]); + 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) @@ -228,14 +286,16 @@ 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}, 0, INT_MAX, FLAGS, "flags" }, + { "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 } }; -- cgit v1.2.3