[PD] Video problems using GEM

Chris Clepper cgclepper at gmail.com
Thu Apr 17 18:34:19 CEST 2014

Does the video just slow down while the image is loading from the disk or
does it stay slow after the image is loaded?

If it is the disk access that slows everything down, preload the still
images into a pix_buffer when the patch starts and then display the images
out of RAM.

I would also resize the stills to no larger than the resolution of the
display.  4600x3456 is a large texture for OpenGL.

On Thu, Apr 17, 2014 at 11:51 AM, Claire O'Connor <oconnc26 at tcd.ie> wrote:

> Hi Chris,
> Thanks for your help. Converting the videos to those formats definitely
> helped. I am using Pure Data in a project which is attempting to create a
> slideshow. I am also using pix_image in conjunction with pix_film for this
> project and everytime I have a video playing and load a picture during that
> time, the video playback slows down. Have you any ideas on how to prevent
> this? I am using JPEGs taken on the same camera as mentioned above (Canon
> Ixus 127 HS) and they are between 3MB and 6MB each. The most images I would
> have banged to load at once is three. Here is some more information on
> those images.
> Any thoughts you might have would be a great help. Thank you!
> On 17 April 2014 14:44, Chris Clepper <cgclepper at gmail.com> wrote:
>> The issue is with the h.264 codec.  On the Mac, compress them as 'Apple
>> Intermediate Codec' or ProRes (which comes with what's left of Final Cut
>> 'Pro').  The files will be much larger in size on the drive but play back
>> much better.  When I wrote the OSX pix_film/movie code long ago, it was
>> only intended to play back intraframe codecs like the JPEG based ones and
>> not MPEG which are consumer delivery formats.
>> You should also set the gemwin to render at least 30 frames per second
>> and for smoothest playback use 60fps which is the refresh rate of an LCD.
>>  I think the default is still 15 or 20fps?
>> On Thu, Apr 17, 2014 at 7:11 AM, Claire O'Connor <oconnc26 at tcd.ie> wrote:
>>> Hi,
>>> I am currently working on a project which uses films with GEM. However,
>>> the films are very glitchy and play very slowly when they load up. I was
>>> wondering if anyone knew anything about how to fix this problem?
>>> The videos used were taken on a Canon Ixus 127 HS and last between 10
>>> and 15 seconds. They are .MOV files and I even tried exporting them as
>>> smaller files but it didn't change their glitchiness. Here is an example of
>>> the file before and after the export with the original file being 80.8MB
>>> and the exported file being 5.9MB. Even with a drastic change in size, the
>>> difference in playback did not change much at all.
>>> Any thoughts and ideas welcome. Thanks!
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