Open the nExt Translation Project!

In 2014 the Serial Experiments Lain PSX Game Translation Project completed, culminating in a 695 page translation reference that gave English speakers the first real window into the game's story. Unfortunately its lofty goal to integrate the translation back into the game was never realized, and the translation had a number of errors.

But what if I told you that with the Close of that World, a new one would eventually Open? Maybe you wished you could play the actual game but with subtitles? Maybe you wanted a better translation?

In fact, a brand new team of dedicated Lain fans have taken it all to the nExt level. They've created a near complete re-creation of the PlayStation game that runs in your web browser! All media plays with English subtitles.

Check it out! https://3d.laingame.net/ It's a little rough around the edges, so if you find an issue be sure to report it.

And here's the source code for the devs out there https://github.com/ad044/lainTSX

Having worked with several members of the team, I must say they have some extremely talented and dedicated people making it all possible.

PlayStation audio and exceptional video quality

I'm still learning about audio in PlayStation games (Nocash Playstation Specifications is amazing!). The XA ADPCM audio format, frequently seen with STR videos, is what I'm most familiar with. But the PlayStation also has a Sound Processing Unit (SPU) that is used to play all other audio you hear in the game.

XA audio is easy to identify and convert. SPU audio, often referred to as "VAG" ("Very Audio Good"), isn't so easy. The easiest clips to identify are simple sound effects that are played and then end. It gets a little more difficult with audio clips that need to loop. Where it gets impossible to identify is when multiple audio clips are combined to form unique sounds in real-time. I believe this is called "SEQ" and is how a lot of background music is done in games. Each instrument is actually little sound clips being played at different frequencies. This brings up another challenge with all SPU audio: clips can be played at any frequency, and there isn't any way to know what it is.

One case where a game used instrumental audio along with STR video is the Valkyrie Profile opening FMV. jPSXdec can only identify the video clip, but has no way to recreate the music. Thankfully, diligent people have put a lot of effort into extracting these instrumental kinds of audio. These are stored in what's known as PSF files. Lo and behold, someone has taken the time extract the Valkyrie Profile instrumental music into PSF files.

With my growing knowledge around PlayStation audio, I thought it would be fun to create a very high quality conversion of the Valkyrie Profile opening. I assume using a PSF converter could produce better quality audio than what you can get on hardware or emulators. jPSXdec can extract the video with the best possible quality which can be made even better with other tools.

Tools used:

• Audio Overload 64-bit
• VirtualDub
• Avisynth 2.6
• nnedi3
• DGMPGDec
• 32-bit static ffmpeg

Steps:

1. Extracted Valkyrie Profile opening video with jPSXdec in avi:jyuv format. This is YUV using the [0-255] component range.
2. Downloaded Valkyrie Profile psf audio clips.
3. Used Audio Overload to convert opening video PSF to wav.
4. Used VirtualDub to mux the video and audio into a single avi, with a 1 second audio delay to sync them up correctly.

5. Created an Avisynth script to upscale the video to HD quality and convert to RGB. DGMPGDec plugin was used for deblocking and nnedi3 plugin for scaling.

   # VALKYRIE.BIN[0]HD.avs
   
   # For deblocking
   LoadPlugin("DGDecode.dll")
   # For scaling
   LoadPlugin("nnedi3.dll")
   
   AviSource("VALKYRIE.BIN[0]jyuv+audio.avi", pixel_type="YV12")
   
   # Deblocking
   # quant is the strength between 1 and 31
   # The quant=31 removed the maximum blocking issues
   # Didn't seem to blur anything else
   BlindPP(quant=31)
   
   # Scale up by 4x for a final resolution of 1280x900
   # The results of nnedi3 appeared slightly better than Spline64Resize
   nnedi3_rpow2(rfactor=4)
   
   # Avisynth has the unique ability to choose the matrix
   # and ChromaInPlacement when converting to RGB (available since Avisynth 2.6)
   # matrix="pc.601" indicates input is in [0-255] component range
   # ChromaInPlacement="MPEG1" is the chroma placement used by PSX
   ConvertToRGB32(matrix="pc.601", ChromaInPlacement="MPEG1")
   

6. Used ffmepg and this script to convert to an uncompressed/RGB/DIB AVI (5 GB file!):

   ffmpeg -i VALKYRIE.BIN[0]HD.avs -acodec copy -vcodec rawvideo VALKYRIE.BIN[0]HD.avi
   

7. That looked good, so then compressed to an almost lossless mp4

   ffmpeg -i VALKYRIE.BIN[0]HD.avi -pix_fmt yuv420p -c:v libx264 -qp 1 -preset veryslow -c:a aac -strict experimental -b:a 192k -ac 2 VALKYRIE.BIN[0]HD.mp4
   

The result turned out pretty good.

In The News

It might be a time for celebration because I've finally bumped jPSXdec into 'beta' status. It's pretty much feature complete now. At worst there may be a redesign of a couple modules as I've recently been hit with the infamous Judge Dredd which breaks some assumptions. I also think the GUI leaves much to be desired (thank you user-testing!).

During the life of jPSXdec I've always been really interested in what people were using jPSXdec for.

In recent news, a project to recreate the game Blood Omen: Legacy of Kain looks to be using jPSXdec to help upsample the videos.

I was going to link to a recently posted, and possibly related HD version of the Blood Omen videos, but to my surprise, Boulotaur2024's YouTube account has been terminated. He's been posting HD versions of several game videos, utilizing jPSXdec for most of the PlayStation ones. It was great because he found a few games that jPSXdec had problems with. Guess Media Interactive Inc. and the Record Industry Association of Japan didn't appreciate his work.

The great ScummVM project has made use of my awesome documentation to add a PlayStation video player so it could utilize the PSX videos from Broken Sword 1 and 2. They've written up a few instructions on how to get your videos ready to play in the emulator.

Replicate

On a whim, I ran one of the unique identifiers in the Lain game through Google which led me to a couple interesting sites.

A very impressive Russian site is trying to recreate most of the game's content for browsing on the web. What impressed me even more is the creator managed to reverse-engineer some of the game's data types before I did. He kindly gave jPSXdec a shout out since it was used heavily to extract nearly everything on the site.

This very old Japanese site I've seen before, but did a good job of documenting the game's content as well.

Translation Hacking

There's been a bit of activity with the translation lately, so I've been working more on the translation tools. Here's real video of the proof-of-concept I posted previously.



I figured it would be a bit rough to use this approach. Unfortunately, anything more than this would multiply the amount of work many times.

I've also discovered there are 34 images on the game discs that don't seem to ever appear in the game. They're not particularly interesting, however.

Decoding MPEG-like bitstreams

While developing jPSXdec for the last 4 years, I've run across three different methods of decoding bitstreams.

If you'd like to learn more about what part this plays in MPEG and PlayStation .STR decoding, check out my thorough document on the subject: PlayStation_STR_format.txt

Approach 1: Brute force

This is the most obvious approach. For each code, peek the next n-bits until the bits match something.

Next17Bits = Peek17Bits()
For Each Possible Code
    If Next17Bits starts with code bits
        Skip bit code length
        If END_OF_BLOCK code
            return END_OF_BLOCK
        Else If ESCAPE_CODE
            ParseEscapeCode()
        Else
            return matching code
        End If
    End if
Next

In the worst case, this approach requires 111 conditional checks to identify a bit code. To be honest, I've never actually seen this implemented anywhere besides by me years ago when first learning about bitstream parsing.

Approach 2: Binary tree

I actually ran across this approach implemented in the Serial Experiments Lain PlayStation game. You have a tree of conditionals testing the value of each bit until a match is found.

If ReadNextBit() == '1'
    If ReadNextBit() == '0'
        return END_OF_BLOCK
    Else
        If ReadNextBit() == '0'
            return ('11+0'.ZeroRun, '11+0'.AC)
        Else
            return ('11+1'.ZeroRun, '11+1'.AC)
        End If
    End If
Else
    If ReadNextBit() == '1'
        If ReadNextBit() == '1'
            // '011s'
            ...
        Else
            // '010... and so on
        End If
    Else
        // '00... and so on
    End If
End If

The branching can be optimized a bit for most leaves: once the length of the bit code is clear, the remaining bits can be used as the index in several small lookup tables. The jPSXdec implementation only requires (in the worst case) 12 branches to determine the longest bit codes.

Approach 3: Array lookup

I believe this type of approach is used in ffmpeg and the Q-gears decoder. Thanks to the unspoken tradition of never documenting anything, I was unable to understand what it was doing. It wasn't until I reverse-engineered the .iki bitstream parsing that I finally saw how this approach works.

At least for MPEG-1 (and PSX STR), you can take advantage of its particular set of variable length bit codes. Only the first code ('11s') and the end-of-block code ('10') need special parsing. The rest of the codes fall under one of three groups. The group a code belongs to can be determined by looking at how many initial zeros it has.

• Group one starts with between 1 and 4 zeros (this also includes the escape code 000001).
• Group two starts with between 6 and 8 zeros.
• Group three starts with between 9 and 11 zeros.

All codes in their groups:

    [Special handling]
    01 // end-of-block
    11s
    ---- [Group 1] ----
    0 11s
    0 100s
    0 101s
    0 0101s
    0 0110s
    0 0111s
    0 00100s
    0 00101s
    0 00110s
    0 00111s
    0 000100s
    0 000101s
    0 000110s
    0 000111s
    0 00001 // escape code
    0 0100000s
    0 0100001s
    0 0100010s
    0 0100011s
    0 0100100s
    0 0100101s
    0 0100110s
    0 0100111s
    ---- [Group 2] ----
    000000 1000s
    000000 1001s
    000000 1010s
    000000 1011s
    000000 1100s
    000000 1101s
    000000 1110s
    000000 1111s
    000000 010000s
    000000 010001s
    000000 010010s
    000000 010011s
    000000 010100s
    000000 010101s
    000000 010110s
    000000 010111s
    000000 011000s
    000000 011001s
    000000 011010s
    000000 011011s
    000000 011100s
    000000 011101s
    000000 011110s
    000000 011111s
    000000 0010000s
    000000 0010001s
    000000 0010010s
    000000 0010011s
    000000 0010100s
    000000 0010101s
    000000 0010110s
    000000 0010111s
    000000 0011000s
    000000 0011001s
    000000 0011010s
    000000 0011011s
    000000 0011100s
    000000 0011101s
    000000 0011110s
    000000 0011111s
    ---- [Group 3] ----
    000000000 10000s
    000000000 10001s
    000000000 10010s
    000000000 10011s
    000000000 10100s
    000000000 10101s
    000000000 10110s
    000000000 10111s
    000000000 11000s
    000000000 11001s
    000000000 11010s
    000000000 11011s
    000000000 11100s
    000000000 11101s
    000000000 11110s
    000000000 11111s
    000000000 010000s
    000000000 010001s
    000000000 010010s
    000000000 010011s
    000000000 010100s
    000000000 010101s
    000000000 010110s
    000000000 010111s
    000000000 011000s
    000000000 011001s
    000000000 011010s
    000000000 011011s
    000000000 011100s
    000000000 011101s
    000000000 011110s
    000000000 011111s
    000000000 0010000s
    000000000 0010001s
    000000000 0010010s
    000000000 0010011s
    000000000 0010100s
    000000000 0010101s
    000000000 0010110s
    000000000 0010111s
    000000000 0011000s
    000000000 0011001s
    000000000 0011010s
    000000000 0011011s
    000000000 0011100s
    000000000 0011101s
    000000000 0011110s
    000000000 0011111s

Each group has its own lookup table of 256 entries, and each code will be associated with one or more entries in the lookup table. After stripping off the minimum number of zeros in the group, no entry in the group will have more than 8 bits remaining in the bit code. For codes that have 8 bits remaining, its value identifies the associated table index. For the bit codes that have fewer than 8 bits remaining, you have to walk through every combination of the remaining bits to find all associated indexes.

Example:

Group 1 code: 00110s
Use 0 for sign bit for now: 001100
Strip off first leading 0: 01100
Find all combinations of remaining bits:

    01100+000 = 96 (table index)
    01100+001 = 97
    01100+010 = 98
    01100+011 = 99
    01100+100 = 100
    01100+101 = 101
    01100+110 = 102
    01100+111 = 103

Thus bit code 00110s will be associated with table indexes 96-103.

Now each table entry needs three values: the inverse discreet cosine transform (IDCT) run of zero-value alternating current (AC) coefficients, the non-zero AC coefficient value, and the length of the bitstream bits that should be skipped.

Once all three tables are constructed, the following pseudo code will parse your bitstream.

If ReadNextBit() == '1'
    If ReadNextBit() == '0'
        return END_OF_BLOCK
    Else
        If ReadNextBit() == '0'
            return ('11+0'.ZeroRun, '11+0'.AC)
        Else
            return ('11+1'.ZeroRun, '11+1'.AC)
        End If
    End If
Else
    Next16Bits = Peek16Bits()
    If NumberOfLeadingZeros(Next16Bits) <= 4
        Match = LookupTable1[(Next16Bits >> 8) & 0xff]
    Else If NumberOfLeadingZeros(Next16Bits) <= 8
        Match = LookupTable2[(Next16Bits >> 3) & 0xff]
    Else If NumberOfLeadingZeros(Next16Bits) <= 11
        Match = LookupTable3[Next16Bits & 0xff]
    Else
        // bitstream error
    End If
    If Match == ESCAPE_CODE
        SkipBits(ESCAPE_CODE.BitLength)
        ParseEscapeCode()
    Else
        SkipBits(Match.BitLength)
        return (Match.ZeroRun, Match.AC)
    End If
End If

Of course the implementation details can vary, but this gives the idea. The Approach 3 I implemented for jPSXdec requires about 8 conditionals to identify a bit code in the worst case. I've found it to be about 10%-15% faster than the Approach 2 I've been using.

PlayStation Video Decoders:The Final Showdown

Updated from the previous comparison with the lastest versions, and three new decoders!

Most importantly, I finally captured what it ACTUALLY looks like on PlayStation hardware (in the dead center).

Those on top get it (more) correct, those on the bottom get it (more) wrong (and ffmpeg and Q-gears are just weird).

Naturally jPSXdec dominates in quality and accuracy. :)

The lineup:

• PSXPlay
• a fixed version of PCSX by Gabriele Gorla
• jPSXdec
• MAME
• PsxMC
• PSmplay
• PsxTulz
• reevengi
• PCSX
• ffmeg
• Q-gears

See the download for all the jucy (and technical) details.

Immaculate Decoding

Just writing a straight-forward PlayStation 1 video decoder has been a lot of work. However, for the absolute most impeccable quality, there is so much more that can be considered in the process.

Upsampling

When PlayStation videos are created, the pixels are broken up into luma (brightness) components and chroma (color) components. Like with JPEG and MPEG formats, 3/4 of the chroma information is thrown away because the human eye can't really tell (this is an example of lossy compression).

When decoding, that lost chroma information needs to be recreated somehow to convert the pixels back into RGB. Unfortunately there is no one 'right' way to do it, because there's really no way to get that lost information back. All you can do is 'guess' by filling in the blanks based on the information around the pixels using some kind of interpolation. Some of the most well known kinds of interpolation are: nearest neighbor, bilinear, bicubic, and lanczos. I've read about more advanced chroma upsampling approaches that also take into account the luma component. This works because there is often a lot of correlation between the luma and chroma components--when the luma changes, the chroma probably will also. I'd like to try to find the best one, but I haven't had much luck on finding many good resources about them all.

Now, because this is essentially just scaling of a 2D image, I've been worried about this article that points out a nasty little gremlin called gamma correction. It seems nearly everyone has been doing image scaling wrong since the popularization of the sRGB gamma corrected color space. I'm assuming video isn't immune to the same problem, yet I've never seen anyone mention it.

Deblocking

Assuming we find the upsampling method of choice, there are still ways the image can be improved. Most video codecs break the frames down into 'blocks', then encode each block separately--again losing information along the way. When everything is reconstructed, that lost information can often be seen as visible distortions between blocks. This problem has been addressed in more recent video codecs such as h.264, but is still a problem with the older MPEG2. I believe nearly all DVD players do some deblocking before showing the final frame.

Even though MPEG2 has been around a long time and deblocking is so common, I've had the darndest time trying to find much mention of what deblocking algorithms are in use today. UnBlock, and this page on JPEG Post-Processing are the best I've come by. I think I've read somewhere that some advanced deblockers can even make use of the original MPEG2 data to improve the deblocking.

I still consider myself a multimedia novice, so there are probably more post-processing methods that would really make the output shine. A big bummer among all research in that area is that if you can think it, you can pretty much count on it been patented.


Given how difficult all this stuff is, I really really wish I could just pass that problem off to the big players in the field, such as ffmpeg (i.e. libavcodec). I've even considered writing a PSX video to MPEG2 video translator so the MPEG2 video can be fed into ffmpeg. Unfortunately there are some big reasons why doing this still makes me uneasy.

IDCT

The PlayStation uses its own particular IDCT approach that I've never seen anywhere else. Given how important it is that the DCT used to encode the video matches the IDCT used to decode, there are no existing decoders that can do it (except jPSXdec of course).

Differences in YCbCr

Another worry is that a real good quality MPEG2 decoder will spatially position the chroma components in the proper location (vertically aligned with every other luma component) as opposed to how I believe PSX does it (the MPEG1 way: in-between luma components).

To make things a bit more complicated, MPEG2 uses the proper Rec.601 Y'CbCr color space with [16-235] luma, and [16-240] chroma range. PSX on the other hand, uses the full [0-255] range for color information. Many video converters don't handle that discrepancy very well. Related to that, pretty much all converters store the data as integers, so any fractional information is lost after every conversion. In contrast, jPSXdec maintains all that fractional information until the very end.

In general though, I have not been impressed with ffmpeg's quality, so I can't suggest people use it when looking for good quality.


One advantage that comes when incorporating all these enhancements in jPSXdec is it provides a much nicer user experience. No need to be hopping between multiple tools to get the best results.

So if I were to actually implement all these features, where would I get the information I lack? Perhaps the doom9.org forums could help. If any multimedia gurus happen to pass by this post, please, if you could, toss some wisdom my way.

YCbCr to RGB Conversion Showdown

In trying to ensure pixel perfect accuracy in my color conversions, I wanted to compare how two popular video converters handle YCbCr to RGB conversion: ffmpeg* and VirtualDub v1.9.8.

The Rec.601 YCbCr to RGB equation is defined as such:

Given Y color range of [16, 235] and Cb,Cr color range of [16, 240].

[ 1.164   0       1.59  ]   [ Y  - 16  ]     [ r ]
[ 1.164  -0.391  -0.813 ] * [ Cb - 128 ]  =  [ g ]
[ 1.164   2.018   0     ]   [ Cr - 128 ]     [ b ]

You can generate a table of the YCbCr to RGB conversion using this bit of code. Values outside valid YCbCr ranges are simply mapped to white.

public class YCbCrAndRgb {
    public static void main(String[] args) {
        for (int y = 0; y < 256; y++) {
            for (int cb = 0; cb < 256; cb++) {
                for (int cr = 0; cr < 256; cr++) {
                    if (y >=  16 && cb >=  16 && cr >= 16 &&
                        y <= 235 && cb <= 240 && cr <= 240) 
                    {
                        int r = (int)Math.round( (y - 16) * 1.164                       + (cr - 128) *  1.596 );
                        int g = (int)Math.round( (y - 16) * 1.164 + (cb - 128) * -0.391 + (cr - 128) * -0.813 );
                        int b = (int)Math.round( (y - 16) * 1.164 + (cb - 128) *  2.018                       );
                        
                        if (r < 0) r = 0; else if (r > 255) r = 255;
                        if (g < 0) g = 0; else if (g > 255) g = 255;
                        if (b < 0) b = 0; else if (b > 255) b = 255;
                        
                        System.out.format("%02x%02x%02x\t%02x%02x%02x", y, cb, cr, r, g, b);
                        System.out.println();
                    } else {
                        System.out.format("%02x%02x%02x\tffffff", y, cb, cr);
                        System.out.println();
                    }
                }
            }
        }
    }
}

Using a pixel format without subsampling should let me convert pixels without blending interfering, however ffmpeg still adds blending even to 4:4:4, which would distort the results. So instead I generated several AVIs with small dimensions (8x8) with fourcc YV12 pixel format (4:2:0), each frame containing one solid color. That came out to 256 AVI files, each with 256*256 frames.

Those AVIs were fed through ffmpeg and VirtualDub and converted to uncompressed RGB AVIs. This ffmepg command converts YCbCr to RGB AVI.

ffmpeg -i inYCbCr.avi -vcodec rawvideo -pix_fmt bgr24 outRgb.avi

Under VirtualDub's Video->Color Depth menu you can set the output pixel format.

A little script walked through every AVI and pulled out the first RGB pixel of each frame and associated it with the original YCbCr color.

At that point I had a table with 256^3 rows and 4 columns:

1. Original YCbCr color
2. RGB generated with the standard equation and floating-point math
3. RGB generated with VirtualDub
4. RGB generated with ffmpeg

Here you can download 4096x4096 images of the resulting RGB values using the three conversion methods.

Floating-point
VirtualDub	ffmpeg

Now to analyze, starting with some visual comparisons. Diffing and autoleveling (normalizing) exposes what pixels are different.

Floating-point vs. VirtualDub

Floating-point vs. ffmpeg

Seems VirtualDub is far more accurate than ffmepg, but still doesn't match the floating-point version perfectly.

Now some numbers.

• VirtualDub has 1795792 pixels (11%) different from the floating-point conversion.
• ffmpeg has 10827725 pixels (65%) different from the floating-point conversion.

Differences broken down by color channel.

I'm disappointed but not surprised that there are so many 1-off values in general. But ffmpeg's variance is as much as -3?? Wow, I hope I'm doing something wrong because that's pretty bad.

In the rare case someone has over an hour and 10GB to spare, along with various strange prerequisites, you can download the scripts used to generate these details.

*

FFmpeg version SVN-r22107, Copyright (c) 2000-2010 the FFmpeg developers
  built on Feb 28 2010 06:11:15 with gcc 4.4.2
  configuration: --enable-memalign-hack --cross-prefix=i686-mingw32- --cc=ccache-i686-mingw32-gcc --
arch=i686 --target-os=mingw32 --enable-runtime-cpudetect --enable-avisynth --enable-gpl --enable-ver
sion3 --enable-bzlib --enable-libgsm --enable-libfaad --enable-pthreads --enable-libvorbis --enable-
libtheora --enable-libspeex --enable-libmp3lame --enable-libopenjpeg --enable-libxvid --enable-libsc
hroedinger --enable-libx264 --enable-libopencore_amrwb --enable-libopencore_amrnb
  libavutil     50. 9. 0 / 50. 9. 0
  libavcodec    52.55. 0 / 52.55. 0
  libavformat   52.54. 0 / 52.54. 0
  libavdevice   52. 2. 0 / 52. 2. 0
  libswscale     0.10. 0 /  0.10. 0

IDCT Demystified (a little)

The inverse discrete cosine transform is a very mysterious and intimidating equation.

(apologies if I messed up the notation)

For the longest time I let the IDCT remain a black box. I found a handful of Java IDCT implementations, plugged them in, and cross my fingers.

I know what the 2D DCT does: it pushes all the image data to the top left corner of the block, while the IDCT undoes that magic. I'm not sure how it does this, but just knowing what it does is enough for me.

But recently I finally discovered that the IDCT is simply a couple of matrix multiplications.

idct_matrix^T . coefficients . idct_matrix

The IDCT equation doesn't really suggest that to the casual mathematician. Of course if you take a class or pay for a book on the subject, maybe this is old news to you.

For those uninformed like me, let's take a closer look at this IDCT matrix.


Theoretically we could throw a bunch of trigonometry identities at this matrix to simplify it, but it turns out to be so much easier to just calculate it and see which decimal values are the same. In the end, there turns out to only be 7 unique values (listed here in varying forms).

1/sqrt(8)       =  cos(  PI/ 4)/2
cos(1*PI/16)/2  =  cos(  PI/16)/2  =  sqrt(2+sqrt(2+sqrt(2)))/4
cos(2*PI/16)/2  =  cos(  PI/ 8)/2  =  sqrt(2+sqrt(2))/4
cos(3*PI/16)/2  =  cos(3*PI/16)/2  =  sqrt(2+sqrt(2-sqrt(2)))/4
cos(5*PI/16)/2  =  cos(5*PI/16)/2  =  sqrt(2-sqrt(2-sqrt(2)))/4
cos(6*PI/16)/2  =  cos(3*PI/ 8)/2  =  sqrt(2-sqrt(2))/4
cos(7*PI/16)/2  =  cos(7*PI/16)/2  =  sqrt(2-sqrt(2+sqrt(2)))/4

Now the IDCT matrix can be simplified to this:

Taking things a step further, let's multiply the two IDCT matrix multiplications out (Maxima is awesome). After a lot of trigonometric simplification, it turns into a massive matrix. This tiny portion below resembles what the entire matrix looks like.


You can download the full 30,000 pixel wide image if you dare.

All those additions/subtractions help to explain why fast IDCT implementations consist of so many sums and only occasional multiplications.

The bare math still makes it difficult to identify patterns, so I took things to the extreme and visualized it a bit.

Writing a Java-only Video Player

Finally designed and put together a fully working implementation, involving a custom blocking queue and 6 threads. I’ve tested it on Windows XP, OS X, and old Kubuntu Hardy. Windows and Mac both look amazing and run perfectly smooth. Unfortunately on Linux the video playback stutters a lot. At first I thought it was due to the GC. After integrating an impressive object pool design, the cause actually turned out to be the Java audio api.

I use the audio playback position to determine when a frame should be displayed. Running a little test exposes how reliable this timer is.

import javax.sound.sampled.*;

public class AudioPositionTest {
    public static void main(String[] args) throws LineUnavailableException {
        AudioFormat audFmt = new AudioFormat(18900, 16, 2, true, true);
        DataLine.Info info = new DataLine.Info(SourceDataLine.class, audFmt);
        SourceDataLine player = (SourceDataLine) AudioSystem.getLine(info);
        player.open(audFmt);
        player.start();

        byte[] abBuf = new byte[2 * 400];

        long lngTestLength = 20 * 1000; // 20 seconds
        long lngTestStart = System.currentTimeMillis();
        long lngTestEnd = lngTestStart + lngTestLength;

        System.out.println(System.getProperty("os.name") + "\tJava " +
                           System.getProperty("java.version"));
        StringBuilder sb = new StringBuilder(400);
        while (System.currentTimeMillis() < lngTestEnd) {
            player.write(abBuf, 0, abBuf.length);
            long lngTime = System.currentTimeMillis();
            long lngPos = player.getLongFramePosition();
            sb.append(lngTime - lngTestStart);
            sb.append('\t');
            sb.append(lngPos);
            System.out.println(sb);
            sb.setLength(0);
            Thread.yield();
        }

        player.stop();
        player.close();
    }
}

Graphing some of the output makes it pretty clear why Linux playback is choppy.

Since that isn’t going to work, my next test will involve registering a listener for start and stop events, and track playback time manually. Though I’m worried my time and the playback time are going to get out of sync.

PSX Video Converter Deathmatch

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UPDATE: This comparison has been superseded by a newer one

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I took 8 different video converters and lined them up for the showdown of the decade!
Ok, so it's not really that dramatic. Some points of interest:

• PCSX shows the most amount of blocky artifacts, which is understandable because its converter was designed for speed over quality.
• PsxMC, PSmplay, PsxTulz, and PCSX all show very similar coloring. PsxMC and PSmplay are especially similar; however, they are not pixel exact matches.
• Q-gears seems to have the darkest and warmest colors of them all, while ffmpeg is the brightest.
• jPSXdec seems to produce softer images than the others, and its colors are quite similar to PSXPlay.

The differences may not seem very apparent side-by-side, but if you align the images on top of each other (like layers) then toggle the top image's visibility, the differences really stand out.

Now which is the most accurate? That depends on your definition of accurate.

1. Do you want the exact values the PlayStation 1 hardware produces?
2. Do you want it to match how you see it on the television?
3. Do you want it to more closely resemble what the original designer created?
4. Do you want a more mathematically precise conversion?

I don't have modded PlayStation hardware, and I don't have any way to very accurately capture composite video output, so I can't investigate #1 or #2.

You need to have the official Sony PlayStation 1 movie converter tool to investigate #3. If some shifty soul wanted to convert this video to STR and send it to me, I could investigate further. ;)

I made my best effort to ensure jPSXdec is very mathematically accurate, so I can at least recommend jPSXdec if you want #4.

Download all the converted images, along with more details (including some source code) on how I did all the conversions.

25Oct2009: updated download with corrections and included convertible test STR.

23Nov2009: updated download with better PsxTulz screenshot (thanks T_chan!).

jPSXdec forever

According to Ohloh, jPSXdec is worth at least $150,000, but that is for code from a year ago. It now has now swelled to over 28,000 lines of code in over 170 files, and will probably be past 30k LOC by next version's release.

I really wish I could work on jPSXdec non-stop until it's ready for prime time again. School, work, the economy, a seriously expensive family emergency, and some critical life changes have all conspired to make that impossible. In fact, I don't have much hope in seeing the next release available anytime this year.

Things completed so far:
* The complicated part of media playback (managing 6 simultaneous threads isn't easy)
* Much needed cleanup of the Tim decoder, XA ADPCM decoder, and serialization code
* Reorganized the arrangement of media streams verses more static types of media
* Fixed both bugs on the issue list.
* Fixed the Tim false-positive matching that happens fairly often
* Fixed FF7 frame-rate miscalculation
* Break things up by game (i.e. setup plugin system)
* ISO9660 file detection
* Improved detection of audio (including CD-i) and video media items
* More robust disc image detection

Still to do:
* Re-implement the saving process for the various media types
* Redo frame rate detection

Beyond the next release:
* Automatic error reporting
* Redo the GUI
* Append AVI writer to make it stricter so it can produce cleaner AVI files
* AVI PNG codec
* Yuv4mpeg2 writing and/or AVI YUV codec
* Real-time media playback/preview
* Searching for static demux and MDEC data
* Finding and uncompressing lhz data, often used in PSX games
* Raw direct CD reading from the disc drive (based on java-avm)
* CD-i video formats
* More game handling
* STR and XA re-encoders
* CD track audio handling

When hell freezes over:
A custom hex browser for jPSXdec. Other free and/or open source hex browsers are generally decent, but none do everything I really need. Some desired features:
* Viewing of very large files without loading the whole thing into memory (hundreds of MB)
* Quick viewing and editing values as big/little endian of varying bit sizes/signs/types
More specifically for PSX hacking
* Identifying and browsing by sector (much like CDmage and IsoBuster do)
* Highlighting of the sector headers and footers
* Viewing of continuous demuxed sector payloads
* Identification of known sector types, and the various fields in each
* An overview map of the entire CD, with quick identifying symbols/colors for every sector and its type
The closest thing I've seen to this is VirtualDub's hex viewer.

And the ultimate pièce de résistance:
* Real-time processing of the data as you mouse-over it, and showing how it results in the final output
* Allows you to take each bit of data in the disc and follow it through the entire decoding process, each step of the way
* Allow you to change anything in real-time, and see how it would turn out
I've repeatedly imagined a program like this for even just mpeg1 or 2 streams. Those streams are really complicated, and you never get to see the direct connection between the data and the output. It would be so neat to hover over a block or a macro block and be able to see exactly where it was going to end up on screen, how it will look, and everything around it. The whole motion detection as well. It would be an incredible tool to teach people how those streams work. In the almost impossible case you've seen the official Bluetooth development tools, that's exactly what I had in mind.

All these neat ideas could eventually turn jPSXdec into the ultimate PSX hacking utility.

The time frame for everything? A long...long time. Years probably. Which really makes me wonder: what will become of this project in, say, another decade? Should I start soliciting help?

In the next to impossible case someone would like to join in developing jPSXdec, his skills might hopefully include:
* Very usable knowledge of Java (no need for an expert because I don't think I am)
* Love and value for clear and well documented source code
* Some experience with reverse-engineering just about anything (media formats preferred)
Added bonus:
* General understanding of mpeg/jpeg-type image formats
* Awareness of cross-platform development issues, and/or experience with developing simple programs for multiple platforms (i.e. Windows, Linux, Mac)

Comparing Media Quality of Playstation 1 games

I suppose very few people have ever looked as closely at Playstation 1 media as I have. Of those that have, I assume most worked for Sony, or developed games using the official SDK. Of the few that never got that approved proprietary insight, almost all are Japanese. Finally, of those even fewer remaining whose primary language is English, almost none care anymore at this late date. So I thought I'd take a moment and share some of what I've observed.

To my knowledge, only one game has actually used custom variable-length (i.e. huffman) codes in its video streams: Serial Experiments Lain. The infamous logo.iki sample may also use custom huffman codes (it sure doesn't use the standard ones), but until I find what game it's from I can't know for sure.

Now I assume S.E. Lain's use of custom variable-length codes means its video quality is higher than if the standard set was used, else why would they use it? Its custom decoding software also took full advantage of every last bit of space available to each frame. I've never seen games using the standard SDK decoder that pushed their buffer to the limit. And if that wasn't enough, it sacrificed as much audio quality as it could to increase space for video bandwidth.

I find this all terribly ironic because the quality of the game's artwork is downright awful.

So while S.E. Lain's video quality is pointlessly top-notch, its sound quality is not only bad, it is probably one of the worst. The audio was encoded very poorly, with many of the loud moments pointlessly sawed to half the dynamic range, creating excruciating distortions.

It's a crying shame, because even though everything about the game was different from the anime series, at least the audio contained more work by the original Lain voice actress, Kaori Shimizu.

Lain's video decoder also took a small speed hit because the data is stored as big-endian. This means that the little-endian Playstation platform has to take a moment to reverse every 32bit value read from memory. Who knows, maybe reversing it would have sped up the animation of Lain while drudgingly browsing all those media items.

The game that I've seen with the next best video quality trick is Alice In Cyber Land. It may be the only game that uses variable frame rates. During times with less video action, the frame rate could be dropped, giving the images more bandwidth for detail. When the action picked up again, the frame rate and quality could return to normal so the more rapid frame changes could be shown. I suspect any game's video could be modified to use this feature. In fact, it's really too bad that the official Sony SDK encoder didn't use this trick. So many game videos might have looked even nicer.

Meanwhile, on the good end of the audio quality spectrum, Square's (now SquareEnix) custom audio format provided the best audio experience of any games I've seen. Its unique format, used in several of their RPGs, produced almost twice the quality of the best standard SDK audio format. An entire sector was devoted to each left/right audio channel, and at intervals that resulted in nearly CD quality output.

Through the Digital Looking Glass

While exhaustively reverse-engineering the Serial Experiments Lain game, always in the back of my mind was an article I read years ago. It describes some curious connections between Lain, and another game called Alice In Cyber Land.
http://www.cjas.org/~leng/alice.htm

So naturally, once the Lain game hacking was thoroughly complete, my attention quickly turned to finding the secrets Alice held.

The work to discover the unique ways the game stored its videos really paid off. The Alice videos were all well animated, and suggested a game that could be a lot of fun. But for now I must be content with its raw Japanese clips, all of which can now be viewed on Youtube.

The Alice In Cyber Land franchise didn't stop with the game. It also included a soundtrack, and short OVA. It seems at least episode 1 was fansubbed by a group called "Boot To Da Head" back in 1997. The first episode is now watchable in very low quality, raw Japanese.

While the connections between Lain and Alice are intriguing, you might be interested to know that they don't end there. Tucked away in a corner of the internet is a little account by one of the game's creators that extends the connections to one more series: Digimon Tamers.
http://www.konaka.com/alice6/tamers/characters/juri-e.html

CD-i

I was pleasantly surprised when I found someone concocted a clever way of using jPSXdec to decode CD-i audio.

As explained in Jonathan Atkins's CDXA documentation, the Sony Playstation 1 and the Phillips CD-i both used the same audio format on their CDs. It never occurred to me that the CD-i likely has a retro community still following it, much like the Playstation 1 does.

This video describes a working solution to extracting CD-i audio with jPSXdec that will work with any game. However, after the extraction, you have to manually break up the audio clips and possibly adjust the speed of some.

Alternatively, you could do the job that jPSXdec can't yet do so the extracted audio clips don't need any extra editing.

If you let jPSXdec do its best to index the CD (or raw music file), it will find all the audio sectors, but fails to concatenate most of the contiguous streams. You're left with several thousand audio clips with a duration of 1 sector. It wouldn't be too difficult to write a script that checks the audio properties (channel, frequency, etc) and finds what sectors should be combined into a single audio clip. It even sounds like someone has already managed to make some headway with this.

Adding better CD-i audio handling to jPSXdec is quite easy, and will be included in the next release (whenever I can get this redesign finished). As for CD-i video, I can't say I have much motivation (or time) to figure it out. But if anyone wants to get their hands dirty and write some decoding code of their own, I'd be happy to support them however I can.

Java real-time video playback

Much of the easy changes have already been made to jPSXdec. The biggest and hardest change left is implementing real-time playback. To do this in pure Java is tricky. I've spent a month looking at every kind of Java video player out there.

I want to keep jPSXdec as cross-platform and simple-to-use as possible (Just Work™). So while the JMF has Java-only implementations for playback, it needs a separate installation, has far more functionality that I need, and being closed source doesn't help. It's curious that even though the JMF has plenty of documented bugs, and hasn't been updated in years, it's still the de facto Java media standard. Meanwhile, the FMJ library is open source, but it's even bigger than JMF, and uses JNI to wield each platform's native playing capabilities. I've examined various other small libraries, but nothing met my needs: a simple synchronized audio and video player. So I'm stuck trying to figure out how to do it myself.

Initially I thought to duplicate the general design of JMF/FMJ since it seems to work for them. It would also help someone with greater familiarity with those libs to take the next step and properly integrate PSX decoding into them. However, after several days of tearing apart those massive libraries, and seeing I'd only scratched the surface, I dropped that idea.

Finally went back and took a closer look at SurePlayer. It plays mpeg1 movies great with very little processor use. It's fully cross-platform, and is a much more digestible library, so I'll be using that as a guide for implementation. With this clear direction, I can push forward with more jPSXdec development. Maybe in several years when Java 7 is ubiquitous, jPSXdec can be changed to utilize the new JMC.

Also during my searchings I serendipitously ran across a Java library to handle cross-platform raw CD reading! It's not quite as clean as I would like, but it's a pretty good foundation to build upon.

In other news, we've had a couple translators pop out of the woodwork recently. Will they be the salvation this project so desperately needs?

A man can dream.

How to encode quality PlayStation 1 video

Recently I've run across a couple of groups trying to replace the video of a Playstation 1 game. As we have to do the same thing with S.E. Lain, I thought I would share some insight as to how it might be done with the highest quality output.

Since there are many things that go into encoding mpeg video, that step is best left to programs that know how to juggle those options, such as ffmpeg. It also allows you to tweak those options, and use its advanced features to get the best results.

So here is how you do it, broken down into 6 ridiculously complicated steps.

1. Convert your video into 4:2:0 yuv4mpeg2, but using the PSX specific rgb->yuv conversion.
2. Feed the yuv4mpeg2 video into ffmpeg at an allowed fps and create a mpeg1 movie with only I-frames (-intra). This should be done at a variety of different quality levels (-qscale from 1 to n).
3. Parse the I-frames out of the movie and parse their macro-blocks
4. Convert the mpeg1 VLCs to PSX VLCs
5. Do this for every mpeg1 quality and pick the one that fits best within the amount of space available to the frame
6. Multiplex the frames and construct all the sectors

If the new video is mostly just the old video with some changes (e.g. subtitles) then quality can improved tremendously with this variation.

5. Use some method to determine which macro blocks to replace (manually picking them, or performing a diff on lossless video data, or a fuzzy diff on lossy video data)
6. Only replace those macro blocks with new ones of the same qscale
7. If the replaced data makes the frame too big, then either replace the entire frame with an ffmpeg created frame that will fit (qscale will probably be bigger), or remove some quality in the frame to make it smaller
8. Multiplex the frames and construct all the sectors

Alternatively have ffmpeg write an AVI using MJPG codec and parse the JPEG frames and convert the JPEG VLCs to PSX VLCs (I'm not sure how to get ffmpeg to produce quality variations with the MJPG codec).

zOMG psx.lain.pl is down!

And it has been for quite awhile. I thought it was just temporary, but finally learned yesterday that the good fellow that was nice enough to host the page has chosen to close the account. We are grateful for the time we could use the server.

Don't worry, we still have all data and work done so far. Unfortunately we're currently without a host, and the project is still stuck at around 14% completion.

I personally would like to thank everyone that has contributed thus far...

Hikari - Translated dialogs from video sequences to Polish.
phm - Extracted the media with jpsxdec and setup the wiki. Retranslated video sequences dialogs from Polish to English. Advertised for translators, and coordinated with their changes.
MercuryTW - Provided some translations from a translator of his own (Keigo). Edited/corrected translated files.
stalker-kun - Provided hosting for the wiki.
otakufish - Provided some translations.
toruvinn - Provided nice domain.
farhan - Ruthlessly proofread random translations, utilising his qualifications in the field of Applied Pedantry with Grammar Nazism.
fishy - Proofread translations, created the public project page.
arc - Provided some translations.
Jossos - Provided some translations.
utakata - corrected a Japanese transcription.
Najica - Provided some translations.
Quibbage - Created subtitle files for videos.

...and everyone else (sorry if I've missed your name here)--thank you all very much.

jPSXdec development has been pretty quiet as well. I should submit the bug that fails to decode some of the Lain videos, or just commit the fix. The next things to do with jPSXdec require some major changes, and things have been busy (my toon won't hit level 60 by itself ;). I'm still here and interested in the project and related topics. I don't plan on that changing anytime soon.

Sonic

AVI
Fixed the obvious problems with AVI writing, but still problems persist.
* My Windows Quicktime install must be bad because it crashes from like everything (but Mac Quicktime plays fine)
* My Linux mplayer must be bad because it plays all movies stretched, one way or another
* All programs on my lappy crash from my movies except Windows Media Player
* My Linux Totem still plays it with green garbage

So I think I may be doing MJPG slightly wrong, but I'm not sure what. Plus I finally figured out why I could never find any documentation on the MJPG codec: "there is no document that defines a single exact format that is universally recognized as a complete specification of “Motion JPEG” for use in all contexts" Wikipedia

Native decoder
Got the native decoder working great on Windows, Linux and Mac. CMake has made cross-platform building a breeze :D It's really exciting to see the decoding plow through dozens of frames per second.

Indeed, native decoding is fast...

Java is faster
The heck?? Contrary to what I thought I saw in my initial tests, my swift Java decoding module is significantly faster than using the native decoder. How? Not sure, but I suspect it's due to all the overhead needed when calling a JNI function (such as changing big-endian to little-endian). It already melts through 150 sectors/second like a hot knife through butter--but since it spends half its time with garbage collection, could it be faster with some object pooling?