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avcodec/pngdec: create a function to decode tRNS chunk.

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Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Benoit Fouet 2014-11-14 10:17:35 +01:00 committed by Michael Niedermayer
parent 4f313a50ee
commit 6499e63f7b
1 changed files with 20 additions and 13 deletions
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33
libavcodec/pngdec.c
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@ -694,6 +694,25 @@ static int decode_plte_chunk(AVCodecContext *avctx, PNGDecContext *s,
return 0;
}
static int decode_trns_chunk(AVCodecContext *avctx, PNGDecContext *s,
uint32_t length)
{
int v, i;
/* read the transparency. XXX: Only palette mode supported */
if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
length > 256 ||
!(s->state & PNG_PLTE))
return AVERROR_INVALIDDATA;
for (i = 0; i < length; i++) {
v = bytestream2_get_byte(&s->gb);
s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
}
bytestream2_skip(&s->gb, 4); /* crc */
return 0;
}
static int decode_frame_png(AVCodecContext *avctx,
void *data, int *got_frame,
AVPacket *avpkt)
@ -771,20 +790,8 @@ static int decode_frame_png(AVCodecContext *avctx,
goto skip_tag;
break;
case MKTAG('t', 'R', 'N', 'S'):
{
int v, i;
/* read the transparency. XXX: Only palette mode supported */
if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
length > 256 ||
!(s->state & PNG_PLTE))
if (decode_trns_chunk(avctx, s, length) < 0)
goto skip_tag;
for (i = 0; i < length; i++) {
v = bytestream2_get_byte(&s->gb);
s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
}
bytestream2_skip(&s->gb, 4); /* crc */
}
break;
case MKTAG('t', 'E', 'X', 't'):
if (decode_text_chunk(s, length, 0, &metadata) < 0)