Silent Debuggers Is A WIP

HuVIDEO is -as its name implied- a video format for the PC Engine developed by Hudson Soft. This format support videos up to 192 by 112 pixels, 10 frames per seconds and 16KHz ADPCM audio.

Here is the list of games featuring HuVIDEO in chronological order:

  • Hudson School Graduation CD ?
  • Power Golf 2 - Golfer / パワーゴルフ2 ゴルファー (HCD4056)
  • John Madden Duo CD Football (TGXCD1045)
  • Ginga Ojousama Densetsu Yuna HuVIDEO CD / 銀河お嬢様伝説ユナ (HCD5078)
  • Kuusou Kagaku Sekai Gulliver Boy / 空想科学世界ガリバーボーイ (HCD5076)
  • Ginga Ojousama Densetsu Yuna 2: Eien no Princess / 銀河お嬢様伝説ユナ2 ~永遠のプリンセス~ (HCD5075)

FIXME research history / Beyond shadow gate code / Rich's doc

Format description

Offset Size (bytes) Description
0 16 Signature
⚬ “HuVIDEO ” for Power Golf 2 and John Madden
⚬ “HuVideo\0\0\0\0\0\0\0\0\0” for Yuna and Gulliver Boy
16 2 Video frame count
18 2 Width (in pixels)
20 2 Height (in pixels)
22 1 Flag (unused)
23 1 VRAM format (0: background tiles, 1: sprites)
24 2 ADPCM buffer length
26 6 Unknown

Power Golf 2

The next 32 bytes following the header contains the palette of the video. The first frame is located 8 sectors away from the header. Frames are stored sequentially. There's no ADPCM and all frames use the palette. All videos have the same size which is 128 by 128 pixels.

Here is the header of one of the video.

Offset Hex ASCII
037394504875564944454F202020202020202020HuVIDEO
037394607700800080000000807C3E807C44807Cw........|>.|D.|

According to the header description, this video contains 119 (77h) frames of 128 (80h) by 128 (80h) pixels encoded as background tiles. As we know that the videos does not contain ADPCM, we can safely the last 8 bytes of the header.

Sector Description
00 header + palette
01 skip
02
03
04
05
06
07
08
09 frame #0
0a
0b
0c
0d frame #1
0e
0f
10

John Madden Duo CD Football

The header is the same as Power Golf 2. The only way to tell if a video has ADPCM is to check its size. There are 3 kind of videos:

  • 128×128 px tiles with ADPCM
  • 256×112 px tiles without ADPCM
  • 128×64 px sprites with ADPCM

The ADPCM data is stored between the palette and graphical data. The length to read is given by the word stored at the offset 24 in the header. As the ADPCM chip in the PC-Engine CD ROM is an Oki MSM5205, the encoding is compatible with Dialogic ADPCM. You can easily replay or convert it with sox. Note that the file must have .vox extension.

sox --rate 16k adpcm_sample.vox sample.ogg

Yuna 2 / Yuna HuVIDEO CD / Gulliver Boy

For those games, the signature changes to HuVideo where spaces are replaced by 0. The graphics are encoded as tiles and the ADPCM length specifies the number of sectors used by a single frame. Unlike John Madden Duo CD Football, the ADPCM is split between each frame. As the video are played at 10 frame per seconds and the audio sample rate is 16KHz, the ADPCM buffer is 800 bytes long. Another difference is that the whole 16 tile palettes are used. An auxiliary array is also stored in order to specify the palette for each tile.

Sector Description
00 header
01 skip
02
03
04 frame #0
4+N frame #1
4+N*2 frame #2

The layout of a frame is as follow:

Offset Description
0 tile data
N0 palette #0
N0+32 palette #1
N0+512 tile palettes
N0+512+w*h/128 adpcm audio

Here N0 is the size of the tile data. With w and h being the width and height in pixels of a frame, and knowing the each tile is 8 by 8 pixels wide, we have:

N0 = w * h * 32 / 8 / 8

The size of the tile palettes is w*h/128 because 1 bytes contains the palettes for two consecutive tiles. The palette of tile i is stored in the last 4 bits, and the one for tile i+1 in the first 4 ones.

Replay routines

Power Golf 2

FIXME

John Madden Duo CD Football

FIXME

Yuna 2 / Yuna HuVIDEO CD / Gulliver Boy

FIXME

References

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