ff_png_get_nb_channels   57 libavcodec/png.h int ff_png_get_nb_channels(int color_type);
ff_png_get_nb_channels  645 libavcodec/pngdec.c         s->channels       = ff_png_get_nb_channels(s->color_type);
ff_png_get_nb_channels 1084 libavcodec/pngenc.c     s->bits_per_pixel = ff_png_get_nb_channels(s->color_type) * s->bit_depth;