#20806 - cory - Tue May 18, 2004 4:15 am
as some of u kno majesco started developing cartoons for the GBA.
well recently i got the Spongebob Volume1 and its so sweet, its got like 5 episodes of spongebob and really nice quality. Only prob is that its 256mbit.
P.S. i really like this site, GBA kicks ass, so does Gba Developing.
~Cory
#20834 - Lupin - Tue May 18, 2004 3:43 pm
Spuntshbop? Very interesting... :P
Maybe you should give a link to the video codec instead of talking about spongebob?
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#21699 - tepples - Thu Jun 03, 2004 5:09 am
I've learned that GBA Video carts don't work on Game Boy Player because Viacom and the other copyright owners complained that unlike a DVD player, the Game Boy Player can't generate Macrovision encoding to prevent people from capturing the output with a VCR.
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#21704 - sgeos - Thu Jun 03, 2004 7:46 am
| tepples wrote: |
| I've learned that GBA Video carts don't work on Game Boy Player because Viacom and the other copyright owners complained that unlike a DVD player, the Game Boy Player can't generate Macrovision encoding to prevent people from capturing the output with a VCR. |
My friend has a setup that allows him to capture DVD output with a VCR. His PS2 is involved somehow...
-Brendan
#21719 - tepples - Thu Jun 03, 2004 6:47 pm
It's probably a modchipped PS2 whose DVD Video decoder no longer generates Macrovision encoding. On the other hand, the GameCube can't generate Macrovision even without a modchip.
(back on topic)
Let's see... 45 minutes per cart, 60 seconds per minute, 12 frames per second in typical American animation, that makes 32400 frames, or about 8 Kbits per frame. Given that Tursi and I have shown GSM RPE-LTP to work well at 30 Kbps (2.5 Kbits/frame at 12 fps), divide this into 5 to 6 Kbits for video and 2 to 3 Kbits for audio.
Assume 6 Kbits/frame for video. At 240x160 pixels, that's only 10 bits per 8x8 pixel block. Of course the naive approach is 2 bits of luminance per 4x4 pixel block and 2 bits to somehow encode color, and you'll just barely beat VideoNow quality. Only interframe redundancy would let one improve much on that. After I get done playing with audio codecs (8ad, Esti, GSM, etc) I may have to try my hand at making my own low-bitrate low-complexity video codec.
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#21720 - poslundc - Thu Jun 03, 2004 7:33 pm
Just curious... since I don't own a DVD player I don't really know about any of this Macrovision encoding stuff, but don't you just run a DVD player to the television through typical RCA component cables? If so, what's to stop you from sending it to a VCR first?
Dan.
#21728 - tepples - Thu Jun 03, 2004 11:58 pm
| poslundc wrote: |
| I don't really know about any of this Macrovision encoding stuff, but don't you just run a DVD player to the television through typical RCA component cables? If so, what's to stop you from sending it to a VCR first? |
Macrovision Video copy protection messes with both the gain control of a VCR's record head and the SECAM-style color encoding that VHS uses. It's the same reason you can't copy a commercial pre-recorded VHS tape to another VCR. However, a $30 video clarifier placed between the source and the VCR will restore the signal to NTSC standard, allowing fair-use copies of greater quality.
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#21735 - wintermute - Fri Jun 04, 2004 4:29 am
| tepples wrote: |
| I've learned that GBA Video carts don't work on Game Boy Player because Viacom and the other copyright owners complained that unlike a DVD player, the Game Boy Player can't generate Macrovision encoding to prevent people from capturing the output with a VCR. |
Interesting. So there *is* a way to detect the GB Player, I wonder if the SP can be detected too.
#21736 - tepples - Fri Jun 04, 2004 4:38 am
| wintermute wrote: |
| tepples wrote: | | I've learned that GBA Video carts don't work on Game Boy Player because Viacom and the other copyright owners complained |
Interesting. So there *is* a way to detect the GB Player, I wonder if the SP can be detected too. |
Sure it can be detected, as some GBA games have rumble when played on a GCN controller. Here's how I've been told detection works: If the GAME BOY PLAYER logo in the proper color is on the GBA's screen, the Game Boy Player will briefly push down all four of the direction buttons at once, that is, KEYS & 0x00F0 = 0. I'm not sure how to actually vibrate the controller though.
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#21936 - tepples - Wed Jun 09, 2004 8:51 pm
I've found RascalBoy Advance runs the Sonic X video just fine.
Audio
The audio is encoded at 16384 Hz. Evidence: RBA's wave output gives a telltale aliasing fold at 8192 Hz. I compared Majesco's audio codec to my GSM player's processing of the same song, and Majesco's has quite a bit more pre-echo (especially in the drum fill at the very beginning of the theme song) and overall hissiness. Perhaps it runs at a much lower bitrate or complexity than the 30 kbps that 18 kHz GSM uses. I'll have to see what my experimental audio codec, the comparatively lower-complexity "Esti", can do at low bitrates.
Video
Chroma (color) is downsampled by 2 in each direction relative to luma (brightness), just as in MPEG. The transform it uses for luma and chroma looks like it could almost be a Haar wavelet transform applied in 2D. Solid color areas seem to have a bit of regular pixelation; I don't know what to make of this.
Given that the whole video+audio stream runs at about 100 kbps, but there are 900 Mpixels, there has to be some sort of use of intraframe correlation, possibly with motion estimation. I'll look into finding telltales of motion estimation.
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#23886 - caitsith2 - Fri Jul 23, 2004 2:44 pm
I have some action replay codes that will allow for the GBA Videos to work on the gameboy player. http://www.caitsith2.com/gba_video_arv3.htm
The codes work by clearing the variable the gameboy player detection code set, just prior to the video actually checking if the variable was set.