• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
  • entries
    37
  • comments
    37
  • views
    36818

misc: FRIR2, (Possible) Alpha + Theora and XviD

Sign in to follow this  
Followers 0
cr88192

854 views

recently was working some on a new interpreter design I was calling FRIR2.

what is it?

basically a Three-Address-Code Statically-Typed bytecode format;
the current intention was mostly to try to make a bytecode at least theoretically viable to JIT compile into a form which could be more performance competitive with native code, mostly for real-time audio/video stuff, while still allowing readily changing scripts (not requiring a rebuild, and possibly interactively being able to tweak things).

made some progress implementing it, but it still has a ways to go before it could be usable (and considerably more work before it is likely to be within the target range WRT performance).

not an immediate priority though.

ADD: FWIW, as-is FRIR2 ASM syntax will look something like:neg.i r13, r9; //2 byte instructionadd.i r14, r7, r11; //3 byte instruction...neg.i r19, r23; //5 byte instructionadd.i r42, r37, r119; //6 byte instruction...neg.v3f r19, r23; //6 byte instructionadd.v3f r42, r37, r119; //7 byte instruction...mov.ic r3, 0L0:jmp_ge.ic r3, 10, L1inc.i r3, r3jmp L0L1:...//with declarations:var someVar:i; //someVar is an integerfunction SomeFunc:i(x:f, y:f) //int SomeFunc(float, float){ var z:f; add.f z, x, y; convto.f t0, z, 'i'; ret.i t0;}
otherwise, more idle thoughts for how to do alpha blending with Theora and XviD (within an AVI).

previously, I had tried the use of out-of-gamut colors, which while able to encode transparency, would do so with some ugly artifacts and limitations (namely violet bands and an inability to accurately encode colors for alpha-blended areas).

another possibility is to utilize some tricks similar to those used by Google for WebM, namely one of:
encode a secondary video channel containing alpha data (implementation PITA, little idea how existing video players will respond);
double the vertical resolution, encoding the extended information in the lower half, and indicating somehow that this has been done (would be handled via a special hack in the image decoder).


current leaning is toward the resolution-doubling strategy, as it is likely to be less effort.

the main issue is likely how to best encode the use of the hack:
somehow hacking it into one of the existing headers (how to best avoid breaking something?...);
possibly add an extra chunk which would mostly have the role of indicating certain format extensions (would need to be handled in the AVI code and passed back to the codec code).

contents of the extended components:
most likely, DAE (Depth, Alpha, Exponent).

Depth: used for bump-maps, possibly also for generating normal-maps via a Sobel filter (or cheaper analogue), ignored otherwise;
Alpha: obvious enough;
Exponent: Exponent for HDR images, ignored for LDR.

likely, DAE would still be subject to RGB/YUV conversions (could be skipped if only alpha were used).


compatibility?
resolution doubling at least should work without too much issue for existing video players and similar, but would double the height of the video for normal players (leaving all the alpha-related stuff in the bottom of the screen).

relevance?
Theora and XviD compress a little better than my BTIC2C format, so this could offer a better size/quality tradeoff, but likely worse decoding speeds (BTIC2C is roughly on-par with XviD as-is while already using an alpha channel);
unlike some other options, this would still not support specular or glow maps.

most likely, this is more likely to be relevant to video sequences than for animated textures, where raw RGB or RGBA is more likely to be sufficient for video sequences.

still not sure if this is a big enough use-case to really bother with though.


performance?
this could potentially require a fairly significant increase in the cost of the color-conversion, doubling the amount of pixels handled and potentially adding some extra filtering cost for normal-maps;
this should still be fast enough for 720p-equivalent resolutions though.

FWIW, a similar cost is implied as with the BGBTech-JPEG format (which supports alpha and normal maps via additional images embedded within the main image).


otherwise, went and added more video textures (to my game project):
water and slime now are video-mapped (using the BTIC1C codec, *);
ended up using 256x256 for the video-textures (was going to use 512x512, figured this was overkill);
discovered and fixed a few bugs (some engine related, a few minor decoder bugs in 1C discovered and fixed, ...);
made a lot of minor cosmetic tweaks (scaling textures, ...);
...

a minor tweak is that 1C will now try to "guess" the missing green and alpha bits based on the other bits;
basically, 1C normally stores RGB in 555 format (vs 565 as DXTn uses), so there is a missing bit;
likewise, for alpha, which is stored using 7 bits, vs the usual 8.

in both cases, the guess is currently made by assuming that the low bit depends on the high bit, so it copies the bit, which while naive, seems to be better than just leaving it as 0.

the other option is preserving these bits, but the quality gain is not particularly noticeable vs the image size increase.


*: note, 1C and 2C are different formats. 1C uses an RPZA-based format (RPZA + Deflate + more features), whereas 2C is loosely JPEG-based (and does RGBA mostly by encoding 4-component YUVA images).

1C is primarily focused on decoding to DXTn. it is effectively LDR only (HDR is theoretically possible, but the size and quality from some tests is "teh suck"). while decoding to DXTn it is drastically faster than most other options.

2C is mostly intended for intermediate video and HDR (it can do HDR mostly by encoding images filled with 16-bit half-floats, and/or using one of several fixed-point formats). speed and perceptual size/quality are a little worse than XviD or Theora, but the image quality is much higher at higher bitrates (ex: 30-70 Mbps).

decode speeds are "similar" to those of XviD (both are fast enough to do 1080p30, but 2C can do 1080p30 with HFloat+Alpha). generally, it is ~80 Mpix/sec vs ~105 Mpix/sec.

if XviD were used at 2x resolution to do alpha, this would likely cut the effective speed to around 53 Mpix/sec.
similar applies to Theora.

note: BTJPEG is around 90 Mpix/sec for raw RGB images, and around 60 for RGB+Alpha, for similar reasons.

this leaves the advantage of XviD and Theora mostly in terms of better image quality at lower bitrates (IOW: not throwing 30+ Mbps at the problem...).

1
Sign in to follow this  
Followers 0


1 Comment


Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now