[Cin] vmodule.c and caching of decoded video?

[Andrew Randrianasulu]

Question:

I was looking at old CinCV repo and found there this commit:

https://repo.or.cz/cinelerra_cv/ct.git/commit/1be2d5c765349982fa1d9b72bdcaaa0377fff05f
r743: Enable caching of frames even when not rendering static frames

diff --git a/cinelerra/vmodule.C b/cinelerra/vmodule.C
 index 65efb0a..841fb40 100644 (file)
 
--- a/cinelerra/vmodule.C
+++ b/cinelerra/vmodule.C
@@ -235,12 +235,12 @@ SET_TRACE
 
 // file -> temp
 // Cache for single frame only
-                               if(renderengine && renderengine->command->single_frame())
+//                             if(renderengine && renderengine->command->single_frame())
                                        source->set_cache_frames(1);
 SET_TRACE
                                result = source->read_frame((*input));
 SET_TRACE
-                               if(renderengine && renderengine->command->single_frame())
+//                             if(renderengine && renderengine->command->single_frame())
                                        source->set_cache_frames(0);
 
 //printf("VModule::import_frame 1 %lld %f\n", input_position, frame_rate);
@@ -306,10 +306,10 @@ SET_TRACE
                        {
 //printf("VModule::import_frame 30 %p\n", output);
 // Cache single frames only
-                               if(renderengine && renderengine->command->single_frame())
+//                             if(renderengine && renderengine->command->single_frame())
                                        source->set_cache_frames(1);
                                result = source->read_frame(output);
-                               if(renderengine && renderengine->command->single_frame())
+//                             if(renderengine && renderengine->command->single_frame())
                                        source->set_cache_frames(0);
 //printf("VModule::import_frame 40\n");
                        }

cehtehs branch of CinelerraCV

in modern CinGG same function done a bit differently, but still only 
enables caching of single frames. Why?

https://git.cinelerra-gg.org/git/?p=goodguy/cinelerra.git;a=blob;f=cinelerra-5.1/cinelerra/vmodule.C;h=6659dd4529e5305b11a053fc4b9c4b6ee47b9a03;hb=HEAD

 292                         int use_cache = renderengine &&
 293                                 renderengine->command->single_frame();

search for more instances of use_cache ....

Of course there might be some bug somewhere preventing  such usage - 
but I really like to see this commented, then ...

Ah, it was  disabled again in
https://repo.or.cz/cinelerra_cv/ct.git/commit/c8d7b9183ac263d540ccbc15b125fc7aaad65311
(part of big 2.1 merge)

I wonder what will hapen if I enable this .. :}
Something else to try ....

As far as I understand, anync decoding  by itself also disabled in CinGG, looking at same module?
But even normal decoding still may leave few frames around, and Cin may reuse them, 
for example for backward playback, no? 

Having some clarification about  what each mode was supposed to do at the top of file will be great ....
Unfortunately, I don't understand Cin enough for making those top comments.. I think.
This idea  obviously can be low priority - just add new module comment each time you edited 
said module ..so, after some time thwy all will contain brief description of their functions
and quircks/historical artifacts, I think

PS; I spend a lot of time trying to debug this bc2000 playback crash - so yes, threading is 
not as simple in impl as I made it on (virtual) paper .. :/