Dear CinGG users, Does anybody want to taste something brand new and unusual? Here is the patch attached: cgg-blendalgebra.diff.gz Apply this patch and rebuild CinGG. The only change is the addition of two completely new video effects, Blend Algebra and Blend Program. The main CinGG code is not affected, so applying the patch is harmless and cannot break anything. After applying the patch, and before executing `make', check that the new created scripts plugins/blendalgebra/BlendAlgebraCompile.pl and plugins/blendprogram/BlendProgramCompile.pl possess executable permissions. After successful `make', don't forget to run `make install': without several important files which must be installed, the new plugins cannot work. Motivation ========== Sometimes there appear again questions / complains regarding overlay blending in Cinelerra, that something appears strange, or not exactly that way as in Gimp (or in whatever), or not in that art the user needs. Fighting such windmills does not seem worth while. The idea here is to create a new specific plugin where the user could program sufficiently short and simple blending algorithms according to his requirements. And of course, without demanding from the user too much programming skills. Firstly I'd like to make a short introduction, a small demo what one can do with the new features. The shortest demo projects are attached here, for several longer ones I'll give the links to download them. This development is already posted to CinGG bugtracker as BT670: https://www.cinelerra-gg.org/bugtracker/view.php?id=670 To look on the following example functions, there is 'Edit...' button in the respective plugin dialog, but you may need a text editor. By default, it is `emacs', and nothing has to be done if it is installed. If not, you can set your favorite editor via the corresponding environment variable, like those: export CIN_EDITOR=kate export CIN_EDITOR=nedit export CIN_EDITOR='konsole -e vim' If text editor is a console editor without its own GUI, it must be run from some terminal emulator, like `xterm' or `konsole'. To open editor from the plugin dialog, some function must be active at that timeline position (its name in text field not empty). Currently, pressing the 'Edit...' button on the empty function does nothing. Either select some existing function first, or enter a name to create a new one from scratch. Example 1. ---------- See ovl2.tar.gz in the attachment Let's say, we are going to write our own implementation of the Arithmetic Subtract overlay function, according to the formula from CinelerraGG manual. Such a function, attached to the Blend Algebra plugin, could look as follows. ------------------------------------------------------------------------ BLEND_ALGEBRA_INIT /* this is a required statement */ COLORSPACE_RGB /* our working color space, can be also YUV or HSV */ PARALLEL_SAFE /* can be safely parallelized */ REQUIRE_TRACKS(2) /* refuse to work if only one track is given */ BLEND_ALGEBRA_PROC /* this is a required statement */ #define s 1 /* mnemonics for source and destination */ #define d 0 R_OUT = R(s) - R(d); /* for red, green, blue, alpha: */ G_OUT = G(s) - G(d); /* result = source - destination */ B_OUT = B(s) - B(d); A_OUT = A(s) - A(d); BLEND_ALGEBRA_END /* this marks the end of our program */ ------------------------------------------------------------------------ And here is an Arithmetic Addition variant, working on any number of tracks. ------------------------------------------------------------------------ BLEND_ALGEBRA_INIT COLORSPACE_RGB PARALLEL_SAFE BLEND_ALGEBRA_PROC int i; R_OUT = G_OUT = B_OUT = A_OUT = 0; /* preinitialize results */ for (i=0; i<TOTAL_TRACKS; i++) /* repeat for all tracks */ { R_OUT += R(i); /* accumulate sum for R,G,B,A */ G_OUT += G(i); B_OUT += B(i); A_OUT += A(i); } BLEND_ALGEBRA_END ------------------------------------------------------------------------ Blend Algebra functions are keyframable, i.e. switchable between plugin keyframes. Untar the ovl2.tar.gz archive from the attachment, load the ovl2.xml project and play it. You can see 30 different functions switched one after another. The source files of the functions have the suffix '.ba'. Example 2. ---------- Let's look on the following short Blend Algebra function: ------------------------------------------------------------------------ BLEND_ALGEBRA_INIT COLORSPACE_YUV PARALLEL_SAFE REQUIRE_TRACKS(2) BLEND_ALGEBRA_PROC Y_OUT = (Y(0)-Y(1))/2+0.5; U_OUT = V_OUT = 0; A_OUT = 1; BLEND_ALGEBRA_END ------------------------------------------------------------------------ What do you think this is? It is nothing else as the famous `ydiff' program, written in less than 10 lines of code and working not externally, but directly inside a Cinelerra plugin. Although this is not yet so complete, the standard ydiff program has an argument to enhance or reduce the difference effect, but we can easily add it here, too: ------------------------------------------------------------------------ BLEND_ALGEBRA_INIT COLORSPACE_YUV PARALLEL_SAFE REQUIRE_TRACKS(2) BLEND_ALGEBRA_PROC Y_OUT = (Y(0)-Y(1))/2*exp((KEY_A-0.5)*14*M_LN2)+0.5; U_OUT = V_OUT = 0; A_OUT = 1; BLEND_ALGEBRA_END ------------------------------------------------------------------------ Here we changed only the expression for Y, adding a factor which depends on the KEY_A parameter in logarithmic scale. The KEY_A parameter itself is interactively controlled by the opacity slider in the Blend Algebra plugin dialog. Good, the ydiff program additionally prints some statistics. This printout can also be implemented by us, although the program becomes slightly more complex: ------------------------------------------------------------------------ static int npix=0; /* these variables will accumulate statistics */ static float sum=0, sabs=0; /* parallelizing not possible here */ BLEND_ALGEBRA_INIT COLORSPACE_YUV REQUIRE_TRACKS(2) printf ("sz=%8d err=%10g abs=%10g", npix, sum, sabs); if (npix > 0) printf (" rel=%10g", sabs*256/npix); printf ("\n"); /* here we print statistics in CGG console */ sum = sabs = 0; /* and clear accumulators for the next frame */ npix = 0; BLEND_ALGEBRA_PROC float diff; diff = Y(0)-Y(1); sum += diff; /* update accumulators */ sabs += ABS (diff); npix ++; Y_OUT = (Y(0)-Y(1))/2*exp((KEY_A-0.5)*14*M_LN2)+0.5; U_OUT = V_OUT = 0; /* and make video track output */ A_OUT = 1; BLEND_ALGEBRA_END ------------------------------------------------------------------------ The statistics is printed in the terminal emulator from which Cinelerra was started. You can look in the ydiff.tar.gz archive. In the project ydiff.xml there are two identical tracks displaced by 1 frame. The ydiff.ba function from the archive has the commented out line #define NO_PRINTOUT. It works slowly because of statistics printout. If you uncomment this definition, statistics will be switched off, the function will run parallelized, noticeably faster. The ydiff.tar.gz archive with this demo can be downloaded from CGG bugtracker (2.5 Mb): https://www.cinelerra-gg.org/bugtracker/file_download.php?file_id=995&type=b... Example 3. ---------- Untar the example archive transitions.tar.gz and load the project transitions.xml. It demonstrates how transition-like effects can be imitated by a Blend Algebra function. Here, depending on the current value of the opacity slider from plugin's dialog, interpolated between keyframes, and the (X,Y) pixel coordinates, the function takes pixels from either track #0 or track #1. The transitions.tar.gz archive with this demo can be downloaded from CGG bugtracker (2.5 Mb): https://www.cinelerra-gg.org/bugtracker/file_download.php?file_id=996&type=b... Example 4. ---------- Untar the archive swap.tar.gz and load the project swap.xml. Now there is another companion plugin, Blend Program, with its function swap01.bp (ending with the .bp suffix). This example resembles the preceding one which imitated transition. The main difference here is that blend program does not return a function result, but modifies any given tracks directly. The program from this example swaps two tracks, along a transition controlled by keyframable interpolated opacity parameter. To see the effect, the bottom track is up-down reflected, and the top one has a mask applied, through which one can see that the bottom track is also being changed. The swap.tar.gz archive with this demo can be downloaded from CGG bugtracker (2.5 Mb): https://www.cinelerra-gg.org/bugtracker/file_download.php?file_id=997&type=b... Example 5. ---------- The preceding example was perhaps somehow artificial demo, not too close to reality. Let's now suggest another application which could be really useful. Untar the ck.tar.gz example from the attachment and load firstly the project ck.xml. There is a still picture and a second track with solid white background on bottom. The blend function attached is: ------------------------------------------------------------------------ BLEND_PROGRAM_INIT COLORSPACE_HSV PARALLEL_SAFE BLEND_PROGRAM_PROC if (ABS(H(0)-KEY_H) < KEY_A*100) A(0) *= SQR((H(0)-KEY_H)/KEY_A/100); BLEND_PROGRAM_END ------------------------------------------------------------------------ It is a rather complete chromakey plugin, writable by user in only six lines of code! Isn't it cool! With these two new small plugins one can do really much! I do not know if a similar functionality exists in any other NLE. Here if the 'Hue' component (in HSV color space) differs from that of the key color defined in the plugin dialog less than by the amount scaled by the opacity slider, the aplha component (the transparency) is set proportional to the squared difference (completely transparent where the two Hues are identical). You can open plugin dialog and turn the slider in it to the left and right and see its effect. Now load another project from here, ckbg.xml. Now there is only one track with the same picture. Instead of the second one which contained the background, there is one more Blend Program plugin attached, its function generating the desired background by itlesf. The background color is set via the color selection dialog of that second Blend Program plugin GUI. ======================================================================== Those who have realized that are not interested in the new features at all, can stop reading here. Who has some interest to try, welcome to read the more detailed README.blendalg description from attachment. As a starting tutorial one could, for example, take some of the overlay functions, modify it to calculate according some other formula and look what changes. Or take the 'background' blend program and implement some dependency on PIX_X and/or PIX_Y to convert solid background to a gradient. If some details in the description attached look too difficult to understand, don't bother, skip unclear sections - perhaps everything will work fine also without reading them. _______________________________________________________________________________ Georgy Salnikov NMR Group Novosibirsk Institute of Organic Chemistry Lavrentjeva, 9, 630090 Novosibirsk, Russia Phone +7-383-3307864 Email [email protected] _______________________________________________________________________________