diff options
Diffstat (limited to 'libavcodec')
| -rw-r--r-- | libavcodec/gif.c | 72 |
1 files changed, 68 insertions, 4 deletions
diff --git a/libavcodec/gif.c b/libavcodec/gif.c index 8c07ee2769..938bc0e928 100644 --- a/libavcodec/gif.c +++ b/libavcodec/gif.c @@ -47,6 +47,7 @@ typedef struct GIFContext { const AVClass *class; LZWState *lzw; uint8_t *buf; + uint8_t *shrunk_buf; int buf_size; AVFrame *last_frame; int flags; @@ -63,6 +64,38 @@ enum { GF_TRANSDIFF = 1<<1, }; +static void shrink_palette(const uint32_t *src, uint8_t *map, + uint32_t *dst, size_t *palette_count) +{ + size_t colors_seen = 0; + + for (size_t i = 0; i < AVPALETTE_COUNT; i++) { + int seen = 0; + for (size_t c = 0; c < colors_seen; c++) { + if (src[i] == dst[c]) { + seen = 1; + break; + } + } + if (!seen) { + dst[colors_seen] = src[i]; + map[i] = colors_seen; + colors_seen++; + } + } + + *palette_count = colors_seen; +} + +static void remap_frame_to_palette(const uint8_t *src, int src_linesize, + uint8_t *dst, int dst_linesize, + int w, int h, uint8_t *map) +{ + for (int i = 0; i < h; i++) + for (int j = 0; j < w; j++) + dst[i * dst_linesize + j] = map[src[i * src_linesize + j]]; +} + static int is_image_translucent(AVCodecContext *avctx, const uint8_t *buf, const int linesize) { @@ -267,6 +300,17 @@ static int gif_image_write_image(AVCodecContext *avctx, int x_start = 0, y_start = 0, trans = s->transparent_index; int bcid = -1, honor_transparency = (s->flags & GF_TRANSDIFF) && s->last_frame && !palette; const uint8_t *ptr; + uint32_t shrunk_palette[AVPALETTE_COUNT]; + uint8_t map[AVPALETTE_COUNT] = { 0 }; + size_t shrunk_palette_count = 0; + + /* + * We memset to 0xff instead of 0x00 so that the transparency detection + * doesn't pick anything after the palette entries as the transparency + * index, and because GIF89a requires us to always write a power-of-2 + * number of palette entries. + */ + memset(shrunk_palette, 0xff, AVPALETTE_SIZE); if (!s->image && is_image_translucent(avctx, buf, linesize)) { gif_crop_translucent(avctx, buf, linesize, &width, &height, &x_start, &y_start); @@ -315,6 +359,11 @@ static int gif_image_write_image(AVCodecContext *avctx, if (trans < 0) honor_transparency = 0; + if (palette || !s->use_global_palette) { + const uint32_t *pal = palette ? palette : s->palette; + shrink_palette(pal, map, shrunk_palette, &shrunk_palette_count); + } + bcid = honor_transparency || disposal == GCE_DISPOSAL_BACKGROUND ? trans : get_palette_transparency_index(palette); /* graphic control extension */ @@ -323,7 +372,7 @@ static int gif_image_write_image(AVCodecContext *avctx, bytestream_put_byte(bytestream, 0x04); /* block size */ bytestream_put_byte(bytestream, disposal<<2 | (bcid >= 0)); bytestream_put_le16(bytestream, 5); // default delay - bytestream_put_byte(bytestream, bcid < 0 ? DEFAULT_TRANSPARENCY_INDEX : bcid); + bytestream_put_byte(bytestream, bcid < 0 ? DEFAULT_TRANSPARENCY_INDEX : (shrunk_palette_count ? map[bcid] : bcid)); bytestream_put_byte(bytestream, 0x00); /* image block */ @@ -335,9 +384,11 @@ static int gif_image_write_image(AVCodecContext *avctx, if (palette || !s->use_global_palette) { const uint32_t *pal = palette ? palette : s->palette; + unsigned pow2_count = av_log2(shrunk_palette_count - 1); unsigned i; - bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */ - for (i = 0; i < AVPALETTE_COUNT; i++) { + + bytestream_put_byte(bytestream, 1<<7 | pow2_count); /* flags */ + for (i = 0; i < 1 << (pow2_count + 1); i++) { const uint32_t v = pal[i]; bytestream_put_be24(bytestream, v); } @@ -350,7 +401,19 @@ static int gif_image_write_image(AVCodecContext *avctx, ff_lzw_encode_init(s->lzw, s->buf, s->buf_size, 12, FF_LZW_GIF, 1); - ptr = buf + y_start*linesize + x_start; + if (shrunk_palette_count) { + if (!s->shrunk_buf) { + s->shrunk_buf = av_malloc(avctx->height * linesize); + if (!s->shrunk_buf) { + av_log(avctx, AV_LOG_ERROR, "Could not allocated remapped frame buffer.\n"); + return AVERROR(ENOMEM); + } + } + remap_frame_to_palette(buf, linesize, s->shrunk_buf, linesize, avctx->width, avctx->height, map); + ptr = s->shrunk_buf + y_start*linesize + x_start; + } else { + 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; @@ -464,6 +527,7 @@ static int gif_encode_close(AVCodecContext *avctx) av_freep(&s->lzw); av_freep(&s->buf); + av_freep(&s->shrunk_buf); s->buf_size = 0; av_frame_free(&s->last_frame); av_freep(&s->tmpl); |