[FFmpeg-devel] Should there be IsAlphaPixelFormat ?
donmoir at comcast.net
Wed Jan 23 01:59:14 CET 2013
Currently I extract the code from swscale_internal.h:
static av_always_inline int isALPHA(enum AVPixelFormat pix_fmt)
const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
return desc->nb_components == 2 || desc->nb_components == 4;
This is useful for to determine if I should create a transparent or non-transparent texture.
Although I don't know why it checks nb_components instead of desc->flags & AV_FMT_ALPHA. nb_components of 2 and 4 always == ALPHA but seems flags should be used instead. AV_FMT_ALPHA is always set for alpha formats.
So I need to include libavutil/pixdesc.h to gain access to AVPixFmtDescriptor.
Wondering if you think this should be exported generally ?
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