PNGEncContext     233 libavcodec/pngenc.c     PNGEncContext *s = avctx->priv_data;
PNGEncContext     426 libavcodec/pngenc.c     PNGEncContext *s = avctx->priv_data;
PNGEncContext     443 libavcodec/pngenc.c     sizeof(PNGEncContext),