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Partial: 2D Animation, video recording improvements...

Posted by BGB, 22 February 2014 · 389 views

well, status recently:
lame...


started working on a 2D animation tool, but then ran into UI complexities;
UI handling in my 3D engine has become a bit of a tangled mess, and there is no real abstraction over it (most things are, for the most part, handling keyboard events and mouse movements...);
there is theoretically support for GUI widgets, but I wrote the code in question 10 years ago, and manage to do it sufficiently badly that doing UI stuff via drawing stuff and raw input handling is actually easier (*1);
sometimes I look into trying to clean up the GUI widgets thing, and am like "blarg" and don't make a whole lot of progress;
other times, I consider "maybe I will make a new GUI widgets system that *doesn't* totally suck", followed by "but I already have these existing widgets, maybe I can fix it up?" followed by "blarg!".

10 years ago I wrote a few things which were ok, and some other stuff which is just plain nasty, but has largely become a black box in that I can't really make it not suck, but also often can't easily replace it without breaking other stuff.


*1: but it is GUI widgets. don't these normally suck?...
well, yes, but this one extra sucks, as it was basically based around a stack-based mapping of XHTML forms to C;
but, without some way to distinguish form instances... so every widget is identified via a global 'id' name, and there may only be a single widget with this name, anywhere. also, no facilities were provided, you know, to update widget contents.
also didn't turn out to really be a sane design for most of the types of stuff I am doing.

so, somehow, I managed to make something pretty much less usable or useful than GTK or GDI...
doesn't help much when looking into it and realizing that there isn't much logic behind it that isn't stuff one would need to replace anyways (some of the structs are useful, but seemingly this is about it).


but, a 2D animation tool, while it needs a UI, doesn't necessarily need a traditional GUI.
"well, there are always modes and keyboard shortcuts!". yes, fair enough, but it doesn't help when one is left with a UI where pretty much everything (in the 3D engine) is a big monolithic UI, and there are few good options for keyboard shortcuts remaining (and "CTRL+F1,CTRL+SHIFT+G" is a bit outside "good" territory).

yes, my 3D modeller, game, mapper, ... all use the same keyboard and mouse-handling code, just with a lot of internal flags controlling everything. in earlier forms of my game effort, it actually required doing an elaborate keyboard dance of various shortcuts to get into a mode where the controls would work as-expected. I then later made the engine front-end set this up by default and effectively lock the UI configuration (short of a special shortcut to "unlock" the UI).


theoretically, I have added a solution to partly address this: now you can "ESC,~" (or "ESC,SHIFT+`") into a tabbed selector for "running programs", along with a possible option for a considered drop-list for launching programs (which would probably work by stuffing commands into the console, probably launching scripts...). clicking on tabs can then be used to switch focus between programs, and possibly allowing a cleaner way to handle various use-cases ("hell, maybe I could add a text-editor and a graphics program and a file manager...", "oh, wait...").

but, on the positive side, effectively this mode bypasses nearly all of the normal user-input handling, allowing each "program" a lot more free-reign over the keyboard shortcuts. architecturally, it is on-par with the console (toggled with "ALT+`", and is sort of like a shell just currently without IO redirection or pipes).

but, OTOH, I am not so happy with the present UI situation...
a lot of this, is, horrid...


thus far, in the 2D animation tool, I can sort of add items and move them around and step between frames (with the movement being interpolated, ...), so it is a start, but still falls well short of what would be needed for a usable 2D animation tool (that is hopefully less effort than the current strategy of doing basic 2D animation via globs of script code...).

probably will need a concept of "scenes", where in each scene it will be possible to add objects and set various keyframes, ... but, at the moment, I am less certain, seems all like a bit of an undertaking.


did at least go and make some improvements to the in-game video recording:
switched from using RPZA to a BTIC1C subset for recording, which has somewhat better image quality and lower bitrate, in this case using a more speed-oriented encoder (vs the main encoder, which more prioritizes size/quality);
basically holds up pretty well with tests for recording at full-screen 1680x1050p24;
made some tweaks to reduce temporal aliasing issues (mostly related to inter-thread timing issues);
also fiddled some with trying to get audio more in sync (recorded video had the audio somewhat out of sync, sort of fudged them more back into alignment via inserting about 400ms of silence at the start of the recording... but this is a crap solution... not sure at present a good way to automatically adjust for internal A/V latency).

the BTIC1C variant encoder basically mostly just uses straight RGB23 blocks (with no quantization stage), and a higher-speed single-pass single-stop entropy backend (uses an extended Deflate-based format). this allows faster encoding albeit with worse compression.

the normal Deflate/BTLZH encoder uses a 3-pass encoding strategy:
LZ77 encode data, count up symbol statistics, build and emit Huffman tables, emit Huffman-coded LZ data.

the current encoder speeds this up slightly by using the prior statistics for building the Huffman table, then doing the LZ77 and Huffman coding at the same time. it also uses another trick which is that it doesn't actually "search" for matches, just hashes the data it encounters, and sees if the current hash-table entry points to a match.

the compression is a little worse, but the advantage is in being able to use the entropy backend for real-time encoding (vs the primary encoder which is a bit slow for real-time).


the temporal aliasing issue was mostly a problem which resulted in a notable drop in the effective framerate of the recording, as I had found that many of the frames which were captured were being lost and many frames were being duplicated in the output. I ended up making some tweaks to the handling of accumulation timers and similar, and the number of lost and duplicate frames is notably reduced.


test from in-game recording: 1680x1050p24 RGB23 uses about 19Mbps, and about 0.46 bpp.
in other tests, this works out to around 6-7 minutes per GB of recording.

this is also a bit better than about 2 minutes per GB I can get from M-JPEG, and seems to have "mostly similar" video quality (and without the JPEG encoder's limitation of being too slow for recording at higher resolutions, which is part of the reason I had switched over to RPZA to begin with).


don't yet have any videos up for the current version.
the most recent video I have at the time of this writing is for a version of the new codec prior to addressing a few image quality issues nor the temporal aliasing or audio sync issues (so the video is a little laggy and the audio isn't really in-sync...).




Added a video:

 

Used BTIC1C via VirtualDub for desktop capture (with a lot of running around in Minecraft) partly to test its viability for this use-case.

 

It is basically usable, though it seems to be at present a little less effective (worse performance and worse compression and with less smooth movement), than when used for in-game video capture. (settings: 1680x1050p24).

 

though, granted, during gameplay, Minecraft was itself lagging to some extent while recording.

then again, MovieMaker didn't help (apparently made the choppiness worse, in retrospect recording at 30 fps might have been better...).

 

still seems basically viable though...

 

it seems pretty competitive with some of my other available options here... doesn't look too awful, can record at full desktop resolution, and doesn't kill the CPU and cause lots of lag.

 

 

EDIT / ADD: the poor compression was due to having accidentally broken the Deflater's hash-function during optimization attempts. this is part is fairly major for correct operation... used a signed "int" where an "unsigned int" was needed...

this effectively caused all attempts to perform match lookups to fail.

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