Commit 0cc9949e authored by Carl Eugen Hoyos's avatar Carl Eugen Hoyos

Mark one colour as transparent in the gif image encoder

if the input palette contains at least one colour
that is more than 50% transparent.

Fixes ticket #715.
parent 51d7cd35
......@@ -62,7 +62,7 @@ static int gif_image_write_header(AVCodecContext *avctx,
uint8_t **bytestream, uint32_t *palette)
{
int i;
unsigned int v;
unsigned int v, smallest_alpha = 0xFF, alpha_component = 0;
bytestream_put_buffer(bytestream, "GIF", 3);
bytestream_put_buffer(bytestream, "89a", 3);
......@@ -77,6 +77,20 @@ static int gif_image_write_header(AVCodecContext *avctx,
for(i=0;i<256;i++) {
v = palette[i];
bytestream_put_be24(bytestream, v);
if (v >> 24 < smallest_alpha) {
smallest_alpha = v >> 24;
alpha_component = i;
}
}
if (smallest_alpha < 128) {
bytestream_put_byte(bytestream, 0x21); /* Extension Introducer */
bytestream_put_byte(bytestream, 0xf9); /* Graphic Control Label */
bytestream_put_byte(bytestream, 0x04); /* block length */
bytestream_put_byte(bytestream, 0x01); /* Transparent Color Flag */
bytestream_put_le16(bytestream, 0x00); /* no delay */
bytestream_put_byte(bytestream, alpha_component);
bytestream_put_byte(bytestream, 0x00);
}
return 0;
......
......@@ -22,7 +22,7 @@
#define LIBAVCODEC_VERSION_MAJOR 53
#define LIBAVCODEC_VERSION_MINOR 41
#define LIBAVCODEC_VERSION_MICRO 1
#define LIBAVCODEC_VERSION_MICRO 2
#define LIBAVCODEC_VERSION_INT AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
LIBAVCODEC_VERSION_MINOR, \
......
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