As regular readers know posts on this blog frequently feature screen caps from the DVD or Blu-ray disk reviewed.  In the process of garnering the screen shots I have found out one or two interesting things about the picture quality of the originating disk.  Using vlc to play disks gives a window the size of the image in pixels.  (I use vlc because for some reason screen caps from DVDPlayer come out blank.)  Older opera DVDs have a picture that is nominally 720 pixels wide giving a 720×540 window for 4:3 pictures.  In practice there are often black bars at the side of screen reducing this a little and sometimes older TV derived material isn’t even really up to even that quality so this really represents an upper bound on the amount of information available.  More recent 16:9 DVDs tend to be a bit more information rich; 830×468 pixels seems quite common and some HD derived material checks in at around 850×480.  It does mean though that very few operas will fit on a single DVD9 disk.  Continue reading →