Re: Displaying a stream of images using GTK



Hi Vladis,

From: Valdis Kletnieks vt edu
To: alok nagdev <aloknag hotmail com>
CC: gtk-list gnome org
Subject: Re: Displaying a stream of images using GTK Date: Thu, 28 Jul 2005 17:53:30 -0400

The single biggest question is "Do you have enough memory or a small enough
video clip that it fits in RAM easily?". If not, you'll need to do some sort
of pre-buffering and/or readahead from disk (think threads here....)

The second question is "Do you need to be able to start displaying the instant Frame 1 shows up, or are you allowed some amount of pre-buffering"? (If you're allowed to run 5-6 frames behind, your timing constraints get a *lot* easier.. ;)

The third question is "How do you define 'fastest way'?".  I've had to deal
with applications that had inbound data at around 30fps, but had to actually output 96fps (stereo 48fps for a VR system), and handling the stereo, the 3D imaging, interpolating from 30 to 48fps, and a lot of really messy mathematical modelling, and suddenly the time budget gets *really* tight. I've had to deal with applications where "30fps is good enough, but we need a minimum-CPU-usage
solution because other things are going on".  And then there's always the
question of "how much trouble are you in if you drop a frame on the floor" (a
fatal error for broadcast TV, a nuisance if you're just playing a DVD for
yourself...).

Clips are quite big and so they would not fit in RAM. I dont need to be able to start displaying instantly, so a lag of a couple of frames should not be a problem. By fastest I meant that although I'm okay with dropping a couple of frames for timing constraints but the least frames I drop works better for me and in the meanwhile gives me more time for image processing stuff, which I'm thinking of avoiding implementing before I get the display thing to work. In that sense I agree on having something like minimum CPU usage solution.

Alok

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