QImage data via FFmpeg

[seveninches]

So memcpy is faster than a bunch of pointer arithmetic.

This is because memcpy copies the data using pointers to 32-bit data (i.e. 4 bytes a time).

The QImage -> QPixmap conversion takes about as long as the data copying.

This is true for X11, because the QImage is on the client side (in your code), and the QPixmap is on the X server side (in a separate process). It should take less under Windows.