Video Output
From Streaming 411
Video Output
Just having the video as a file somewhere does us little good if we're unable to play it back on the device that we need. In order to play back our video we have to be able to talk to the video hardware. This is where many differences in operating systems and hardware platforms come into play. Every major Operating System has it’s own layer for handling multimedia.
- QuickTime
- SDL (Simple DirectMedia Layer)
- DirectShow
Of all of these, we will focus on QuickTime and also take a look at SDL, since it’s the most cross-platform of them all.
In addition to QuickTime, the Macintosh Operating System also provides hardware-accelerated low-level video processing capabilities through a technology called Core Video. We’ll also take a look at this. QuickTime is a very good case study subject because it’s very mature. You can see this in the development frameworks - you can write a simple video player without writing a single line of code using QuickTime, whereas ffplay, the barebones test app bundled with ffmpeg, is over 2 700 lines long.
The playback software takes our encoded media, picks the correct decoder and "streams" that to the video hardware. Let's take a look at exactly how this process works: http://www.libsdl.org/cgi/docwiki.cgi/
We’ll go through the process fo video playback by building a prototype playback program, called Helo.
Syncronisation This was the original problem behind several multimedia platforms - how to keep images and sound in sync…
