Hi,
When opening a media i need to check if the pixel format holds an alpha channel.
I can check for the alpha flag in the pixel format description, like this:
const AVPixFmtDescriptor *pixDesc = av_pix_fmt_desc_get(pix_format);
bool has_alpha = pixDesc->flags & AV_PIX_FMT_FLAG_ALPHA;
But i noticed that inside libavutil/pixdesc.c there is a function for checking for an alpha channel, which is defined like this:
#define pixdesc_has_alpha(pixdesc) ((pixdesc)->nb_components == 2 || (pixdesc)->nb_components == 4 || (pixdesc)->flags & AV_PIX_FMT_FLAG_PAL)
I understand the use of AV_PIX_FMT_FLAG_PAL as it is an exception, but could a pixel format with alpha have a number of components different from 2 and 4?
So, which one of the two methods is more reliable?
Any advice would be much appreciated.
Thank you,
Simone.
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