Opening Intro of Game “SeeIn AO” and CD-DA Audio Track Emulation

SeeIn AO (Japanese title: SeeIn青~シーンAO~) is a game initially released in year 2000 by Japanese game company Alice Soft. This game employs a single CD-ROM disc as its physical medium. A digital download version of this game has never been released ever since. You may ask, why? Let’s explore the real reason behind it.

If you play this game without inserting the CD-ROM disc into your CD/DVD drive, you will find that: Firstly, you won’t hear any music because by default this game plays music from CD-DA tracks on the CD-ROM; and secondly, you will also find that this game won’t play the opening intro or the ending outro, as if they didn’t exist at all.

For the lack of music without the CD-ROM, you can still toggle the game’s internal setting by switching from default CD-DA audio to inferior MIDI audio; but there is no setting that can enable the opening intro or the ending outro without the CD-ROM.

This is because the opening intro and the ending outro are not stored as standard video files in the game folder, nor are they stored as “VCD tracks” on the CD-ROM (Yes, VCD was a thing before DVD and BluRay). In fact, if you had never inserted the game’s CD-ROM into your CD/DVD drive while playing the game (be it a physical CD-ROM disc or a virtual CD-ROM image mounted on the system), you probably wouldn’t even notice that the game has dedicated opening intro and ending outro.

Yet by decompiling the game’s script pack file, we accquire the knowledge that the game’s opening intro and ending outro do exist. They are actually each comprised of a sequence of panning, fading and transitioning of a mere handful of static images spiced up with some special effects. The sequences themselves, which are just scripts, are closely synced up to the playing time of the CD-DA audio track to achieve a frame-by-frame like animation. Without the CD-DA audio tracks on the CD-ROM, the scripts are not able to get accurate sync-up timing references, so the developer decided (maybe unintentionally?) to completely skip the opening intro and ending outro in the absence of CD-ROM audio tracks.

Theoretically it is still feasible to use the playing time of the bundled MIDI music instead of the CD-DA music as sync-up references for the opening intro and the ending outro. But unfortunately the CD-DA audio tracks accompanying the opening intro and the ending outro are not pure music but human voice dubbed songs, which can not be reproduced by MIDI, as MIDI is basically just well timed instructions for music instruments. If you browse through the MIDI library provided by the game, you will find that the total number of MIDI music is 2 pieces fewer than the CD-DA audio tracks on the CD-ROM. And yes you’ve guessed it right: They are the opening song and the ending song.

Nowadays, probably your PC isn’t even equipped with a CD/DVD drive. However, not all is lost. We still have a savior in the CD-less world: CD audio emulation. I am not talking about the traditional CD-ROM image file with a virtual CD drive emulator; I am talking about the CD-DA audio emulation that does not require a CD-ROM image file. One benefit is that you don’t need to store the whole CD-ROM image any more, as audio tracks on a CD-ROM are literally uncompressed PCM wave audio files, which can be compressed to around 10% of their original size without your hearing any difference even on top notch Hi-Fi sound systems. And the CD-DA audio emulation takes this advantage to the practice: You can shrink a 700MB game CD-ROM (either a physical disc or a virtual image) into a 70MB game folder, still with full CD level quality audio. And the best part is that you don’t need to hack the game’s program in order to achieve this.

How to get this magic you ask me? Head to https://github.com/ayuanx/ogg-winmm/ and help yourself. You can do it! And don’t forget, this magic not only applies to the aforementioned game, but also to many many other games and programs. Try it with other CD audio based games and see for yourself, you might be surprised.

About AyuanX

Big Brother is watching you! Yes, you!
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