>Psychtoolbox>PsychDemos>MovieDemos

LoadMovieIntoTexturesDemo(moviename [, fromTime=0][, toTime=end][, indexisFrames=0][, benchmark=0][, async=0][, preloadSecs=1][, specialflags=0][, pixelFormat=4])

A demo implementation on how to load a movie into standard
Psychtoolbox textures for precisely controlled presentation timing and
presentation order.

Parameters:
moviename - Filename of moviefile to use. If none is provided, then the
simple DualDiscs collision movie is used which is part of PTB.

fromTime - Start time (in seconds) from which the movie should be read
into textures. Defaults to start of movie, if not provided.

toTime - End time (in seconds) upto which the movie should be read
into textures. Defaults to end of movie, if not provided.

indexIsFrames - If set to 1 then the fromTime and toTime parameters are
interpreted as frameindex (starting with 0 for the first frame), instead
of seconds. If set to 2 then presentation timestamps are ignored for the
decision when to stop loading a movie. This is needed for certain movies
with a broken encoding of time, as those would stop loading way too early
otherwise.

benchmark - If you set this parameter to 1, the demo will compute the
time it takes to load the movie, and - after the movie has been loaded
into textures - the maximum display speed without syncing to vertical
refresh. All visual progress feedback is disabled. This is mostly
useful to benchmark different movie file formats and codecs for their
relative efficiency on a given machine. A setting of 2 will additionally
disable test of abort keys during loading of the movie - to discount
possible pollution of the benchmark results with time spent checking the
keyboard. A setting of 3 will also skip keyboard queries during the load
phase, additionally it will not queue up textures in video memory, but
instead load a texture and then immediately discard it. This is more
resembling typical movie playback, where a frame is pulled, presented on
screen, then discarded. It tests a different decoding path in Screen(). A
setting of 4 will only test decoding performance of the movie, but omit
creation of actual Psychtoolbox textures for presentation. This allows to
separate computation time spent in the video decoder from time consumed
by the graphics driver or graphics card.

async - If you set this parameter to 4, the video decoding engine will
prebuffer frames ahead of time, up to ‘preloadSecs’ seconds worth of
video data. This is unsuitable for playback with audio-video sync, but
for pure video playback it can decouple decoding from presentation
further and provide a potential performance boost for very demanding
playback scenarios.

preloadSecs - How many seconds of video to prebuffer if async == 4?
Specify a maximum amount in seconds, or the value -1 for unlimited
prebuffering.

specialflags - Special flags for ‘OpenMovie’. E.g., a setting of 1 will
try to use YUV textures for higher performance, if the installed graphics
card supports this. A setting of 4 will always use YUV decoding, by use
of out own builtin YUV decoder, which may be more limited in
functionality and flexibility, but helpful if highest performance is a
requirement.

pixelFormat - Format of video texture to create: 1 = Luminance/Grayscale
only, 2 = Luminance+Alpha, 3 = RGB color, 4 = RGBA, 5 = YUV-422 packed
pixel, 6 = YUV-I420 planar format. 5 and 6 = Y8-Y800 planar luminance
only format. Not all formats are supported by all GPU’s, operating
systems and video codecs. Defaults to 4 = RGBA 8 Bit per color channel.

How the demo works: Read the source code - its well documented ;-)

This demo “preloads” the movie into textures:
The whole movie gets read into PTB textures before start of trial. Then
you show the textures in quick succession like in PlayMoviesDemo. The
advantage of this approach is exact control over display timing and
display order: You can show frames in any order you like at any rate you
like (and that your hardware likes). Disadvantage: Longer trial
setup time for loading the whole movie, higher memory consumption (keep
all n frames in memory instead of only the current one) and the inability
to play sound in sync with video.

To make it a bit more interesting, you can use this demo to “browse” short
videoclips, e.g., for selection of interesting parts…