03 November 2016, 13:15 | #61 | ||
Registered User
Join Date: Jun 2015
Location: Germany
Posts: 1,918
|
Quote:
Quote:
|
||
03 November 2016, 14:10 | #62 |
Ya' like it Retr0?
Join Date: Jul 2005
Location: United Kingdom
Age: 49
Posts: 9,768
|
I will put the cat amongst the pigeons here :
If an ASM coder codes for an 060 - but lets say shuns the V2 - doesn't this belay the point of programming on an 060? After all, if speed isn't your thing surely an 020/030 is more applicable as more people have access to it. Now I will probably answer my own question : The 060 has a defined *static* ISA as well as an MMU and FPU where as the V2 is in state of flux (optimizing and additional register sets included) - in this regard until the V2 core is matured and finalized - it will make it diffcult to coders as it would be like playing a game of football with the goal posts changing position after every kick. In the meantime : How cool is it that I can watch Top Gun in 640x480 on my A600!!!! As a developer - think of the possibilities of FMV used in conjunction in game or applications - freaking exciting if you ask me! |
03 November 2016, 14:25 | #63 | |
Registered User
Join Date: Feb 2010
Location: Espoo / Finland
Posts: 818
|
Quote:
When it comes to the demoscene 060/AGA has been the de facto accelerated Amiga platform for almost 20 years, which is why people stick to the 060. And in the past few years there's also been a renewed interest in going back to the basics and doing stuff for the A500, which I think is a good thing. |
|
03 November 2016, 17:06 | #64 |
Registered User
Join Date: Aug 2007
Location: berlin/germany
Posts: 1,054
|
it is a good thing to serve the lowest common denominator and widest possible audience where applicable, i agree. but i do not feel that apollo proposal availability must necessarily be in conflict with this especially as soon as we agree upon the above.
extra stuff like instruction set or api extensions may be sparely used where they are of notable importance for speed or functionality, similarly like asm inlines. the thing is not everybody is convinced that it would be most beneficial attitude. some folks insist on coding everything in 68k asm, others say 68k is too outdated, they need os4 interfaces. |
04 November 2016, 00:01 | #65 | |
Registered User
Join Date: Dec 2013
Location: Lake Havasu City, AZ
Posts: 741
|
Quote:
The additional instructions (some of which have come as direct result of PCx), are a welcome addition to the core. The recent AMMX usage (I say recent, but AMMX has been in the core for awhile) gives a FREE boost in performance by using the instructions. Nobody is forcing you to use those instructions in your code, but I would say it is rather "clever" to use those if they are available. I write only in assembly (no matter what CPU I am using), and have since 1979. The 68080 (a name I don't particularly care for really) is an excellent superscaler CPU core, with lots of flexibility from a programmer's stand point. It's also a breath of fresh air for Amiga enthusiasts who want the fastest possible CPU. I don't see anything wrong with the Vampire project - and if I did, I sure as hell would not be involved. Last edited by JimDrew; 05 November 2016 at 06:55. |
|
09 November 2016, 07:24 | #66 |
Apollo Team
Join Date: May 2014
Location: not far
Posts: 379
|
RiVA 0.50 sources have been released publicly on Aminet.
http://aminet.net/package/gfx/show/RiVA-src Let's skilled ASM coders improve it now Last edited by TuKo; 09 November 2016 at 08:38. |
09 November 2016, 09:38 | #67 |
Registered User
Join Date: Jun 2015
Location: Germany
Posts: 1,918
|
Finally talking ends and coding begins.
|
10 November 2016, 19:13 | #68 |
Registered User
Join Date: Jun 2010
Location: PL?
Posts: 2,741
|
Is there any way to estimate hypothetical speed gain if instead YCbCr color space YCgCo color space will be used in video source (assumption it is easier to recode on PC video from YCbCr to YCgCo and at the same time some processing can be performed - for example resizing to match Amiga graphics HW capabilities).
https://en.wikipedia.org/wiki/YCgCo#YCbCr_color_model |
10 November 2016, 21:21 | #69 | |
son of 68k
Join Date: Nov 2007
Location: Lyon / France
Age: 51
Posts: 5,323
|
Quote:
I don't think it can be easily tested because YCgCo isn't supported in MPEG-1 (only format supported by Riva). For this MPEG-4 support has to be added (but h.264 would be a lot more cpu intensive). |
|
11 November 2016, 04:27 | #70 |
Total Chaos forever!
Join Date: Aug 2007
Location: Waterville, MN, USA
Age: 49
Posts: 2,186
|
There is one thing that is right about Meynaf's line of thinking. The Vampire version of RiVA uses a screenmode that implements the luminance and chrominance color space conversion to RGB thus AMMX is not the only optimization.
|
11 November 2016, 09:14 | #71 |
Registered User
Join Date: Jun 2015
Location: Germany
Posts: 1,918
|
AFAIK at least some RTG cards also have such modes.
|
11 November 2016, 10:24 | #72 |
Total Chaos forever!
Join Date: Aug 2007
Location: Waterville, MN, USA
Age: 49
Posts: 2,186
|
|
11 November 2016, 14:00 | #73 | |
Registered User
Join Date: Jun 2010
Location: PL?
Posts: 2,741
|
Quote:
MPEG-1 fully support YCgCo (just set matrix coefficient as 8 - normally it is reserved for future use in MPEG-1 and MPEG-2 but it is fully specified for H.264 and H.265 - problem is that nobody use MPEG-1 so it is uncommon practice to use YCgCo as it is not popular even nowadays but Amiga have limited processing capabilities so any gain is valuable (as every pixel need to be converted from YCbCr to RGB and later to Amiga HW limitations). Side to this Intra frame formats should be less intensive especially H.264 (without CABAC and deblocking loop which takes like 50 - 60% of decoder processing power). I can made streams for testing if this is a problem. |
|
11 November 2016, 19:35 | #74 | |
Registered User
Join Date: May 2016
Location: Rostock/Germany
Posts: 132
|
Quote:
In terms of H.264, I'm not sure whether it would really help to save cycles on a humble 68k. Correct me if I'm wrong and missed an amendment to AMD 1, but FRExt states that YCoCg is legal only with chroma_format_idc=3, i.e. 4:4:4 and at least 9 Bit for Chroma in H.264. So when the effective pixel count doubles and 8 BPP is no longer sufficient for storage, the resulting tradeoff might well swing in an unfortunate direction (when staying standards-compliant). |
|
12 November 2016, 07:04 | #75 |
Registered User
Join Date: Dec 2013
Location: Lake Havasu City, AZ
Posts: 741
|
The player using AMMX instructions is more than twice as fast as the version that doesn't use these instructions, using the same Vampire setup. I am not sure how much clearer this needs to be.
|
12 November 2016, 10:41 | #76 |
son of 68k
Join Date: Nov 2007
Location: Lyon / France
Age: 51
Posts: 5,323
|
This is valid only if the AMMX instructions are the only change between these two versions, which apparently isn't the case. Have you seen the actual code ?
|
12 November 2016, 13:57 | #77 | ||
Registered User
Join Date: Jun 2010
Location: PL?
Posts: 2,741
|
Quote:
Side to this i think about building OCS/ECS VIDIOT (aka Video DAC) to support HW YCgCo to RGB conversion (in AGA as external module) - it can operate on analog signal so it will be possible to remove YCgCo to RGB conversion step - maybe similar principle as Archos AVideo. Quote:
I don't see any YCgCo limitation mentioned by you - are you able to use latest official specification and confirm this? https://www.itu.int/rec/T-REC-H.264-201602-S/en Additionally - YCbCr is more lossy (RGB -> YCbCr -> RGB) than YCgCo -YCbCr require between 1 - 2 bits more than YCgCo to perform fully reversible RGB conversion. Finally i would say that we should not stuck with perfect compliant decoder for Amiga - i see no problem to create Amiga optimal format based on widely accepted standards and if possible use those standards as much as possible but in Amiga every CPU cycle count so... we can anyway pre-code videos on PC (resizer quality will be always higher quality on modern CPU - Amiga probably can do real time bilinear or cubic at best without de-gamma when PC easily may precode linearized/de-gamma video with spline + something like MSAA/FXAA to reduce aliasing and improve visual quality on low res Amiga screen). I agree - it should be standard as much as possible but to squeeze all possible cycles perhaps it is good to select subset of codec functionality to keep healthy balance between quality\speed\compatibility. |
||
12 November 2016, 15:02 | #78 | |
son of 68k
Join Date: Nov 2007
Location: Lyon / France
Age: 51
Posts: 5,323
|
Quote:
As ISO specs are difficult to find and not exactly straightforward to read, is it possible to find some reference code that would compile on Amiga ? |
|
12 November 2016, 18:22 | #79 | ||||
Registered User
Join Date: May 2016
Location: Rostock/Germany
Posts: 132
|
Quote:
The idea of putting an external conversion HW to the RGB port is very nerdy, if I may say so (if not pls accept my apologies). As a side note that doesn't necessarily coincide with your particular interests, YCbCr output would work with the same approach, even leading back to the good old YUV. I'd expect some artifacts having to be addressed cleverly when thinking of colorful images by means of HAM. I'd be interested to hear about such projects going forward. Quote:
Quote:
The consideration towards bit depth boils down to the question whether one is able to handle the necessary bit rate where such details become truly relevant. The sheer abundance of computing power and storage capacity on the usual platforms these days allow that for interested parties, for sure. The classic Amiga is "a little" handicapped in this department (see below fo an example, please). Quote:
At this point, my experience on a constrained platform like 68k (even the modernized interpretation that caused some stir in Amiga-land) is that you can ill afford algorithms that have become "usual" on the modern platforms. Just today I had to step back a bit and re-calculate on performance figures. An algorithm that just takes an average 5 cycles per pixel amounts to quite some numbers when it comes to video. So when you run video in a by current standards modest resolution of 640x360, this amounts to 1152000 cycles per frame or 28.8 MHz at a desired rate of 25 FPS. Oops. My poor A500. |
||||
12 November 2016, 18:42 | #80 | |
son of 68k
Join Date: Nov 2007
Location: Lyon / France
Age: 51
Posts: 5,323
|
Quote:
|
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
Thread Tools | |
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
RiVA mpeg player | amiga | request.Apps | 18 | 25 February 2014 10:32 |
ACA1231 vs M-Tec 1230 vs A630 benchmarks | alenppc | support.Hardware | 4 | 11 July 2012 18:39 |
Some benchmarks, and a request | Damion | support.Hardware | 29 | 14 March 2011 16:10 |
riva | amiga | request.Apps | 6 | 12 May 2008 18:56 |
Benchmarks. | ECA | support.Hardware | 4 | 14 June 2002 15:14 |
|
|