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Old 06-15-2016, 10:18 AM   #361
geekmaster
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Quote:
Originally Posted by Pnpn View Post
Hi
I've installed gmplay on my kindle PW, and it works great but the video is displayed at a 800x600 resolution (PW is 1024x758) and so appears on the top left of the screen.
Is there a way to change the resolution of the player to have a full frame image on the paperwhite ?
thanks for your help!
Quote:
Originally Posted by ppoo View Post
@Pnpn, you can chage gmplay source(click Magic revealed button here) to
line
Code:
#define FBSIZE (600/8*800)
to
Code:
#define FBSIZE (758/8*1024)
then compile it and run.
You would also need to change the video transcoder (raw2gmv) to the new resolution, and encode some videos in that resolution. They are pre-dithered by the transcoder program, and the player just spits the video lines onto the display.

Your larger videos would probably work as-is on the smaller 800x600 kindles (with the larger resolution video player), but only part of the image would be visible. Also a possibility that it could throw an error if the last line extends beyond the end of the framebuffer, but newer kindles have really large framebuffers, so unlikely.

Because the GMV video format contains no metadata to describe resolution, the 800x600 resolution (common to all kindles at the time of its development) was the default value.

For the new version (in progress) I plan to add metadata file headers, so I can support multiple resolutions, in addition to interleaved sound, and I will call them GMM (geekmaster multimedia) files. The new player will also support legacy GMV files, if no file header is found.

Last edited by geekmaster; 06-15-2016 at 10:29 AM.
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Old 07-17-2016, 06:03 PM   #362
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I am working on this project again. I was worried about keeping sound synchronized to video, but according to the following youtube video, sound can be up to 45msec early or up to 125msec late and still be perceived as simultaneous with the video. Because I am doing one frame every 130 msec, it looks like according to this information, I have a 170msec window of acceptable temporal variability for video framerate, in which I need to put the audio frames into.

Because some frames can be delayed, I should probably make the audio play nearly 45msec early, allowing it to get a full frame behind (130msec, with another 40msec to spare for extra long eink updates). This may take a bit of experimentation to find the optimal audio lead time, but should be pretty flexible.


EDIT: In that video, he says 125msec delay, but later says 100msec in the basketball demo. However, the shorter 145msec total delay still gives a full frame plus 15msec frame delay being perceptually accepted as simultaneous.

Last edited by geekmaster; 07-18-2016 at 12:02 AM.
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Old 07-17-2016, 10:29 PM   #363
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Though my published versions of gmplay (posted in the first post) allow video to lag up to a full second to prevent visible frame drops when eink updates take a lot longer than usual, for audio sync I plan to always display the most recent frame (allowing only up to a single frame delay before frame dropping). In essence, I will display the video frame that most closely matches the audio being played, within that 170msec time window. With video frames presented 130msec apart, it will be easy to choose which frame to display even assuming that the frame could take longer than normal to become visible on the eink display. All good, so my previous worries can be put to rest.

Now the problem is how to get ALSA sound compiles working again on my new build system. Missing dependencies to figure out...

Last edited by geekmaster; 07-17-2016 at 11:55 PM.
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