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LBA (Logical Block Address) optimization is crucial for PlayStation game performance. By controlling the physical location of files on disc, you can minimize seek times and improve loading speeds.

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Understanding LBA

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What is LBA?

LBA (Logical Block Address) is:
  • The physical sector number on the CD
  • A sequential address starting at 0
  • The actual position data is written on the disc
  • Critical for CD drive seek performance

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Why LBA Matters

CD drive characteristics:
  • Seek time: 100-500ms depending on distance
  • Read speed: ~150-300 KB/s (1x-2x)
  • Rotational delay: Varies with position
  • Access pattern: Sequential reads are fastest
Optimizing LBA placement can reduce loading times by 50% or more.

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How mkpsxiso Handles LBA

mkpsxiso provides precise LBA control:
  • File order = LBA order: Files are written in XML order
  • No automatic sorting: Unlike mkisofs, order is explicit
  • Manual optimization: You control placement
  • Predictable layout: Same XML produces same LBA layout
This is mkpsxiso’s key advantage over generic ISO tools. You have complete control over file placement for optimal loading performance.

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Basic Optimization Strategy

1

Identify Access Patterns

Analyze how your game loads files:
  • Boot files: Loaded first (system.cnf, executable)
  • Menu data: Loaded during menu screens
  • Level data: Loaded when entering levels
  • Streaming media: Played during gameplay
Document which files are accessed together.
2

Group Related Files

Place files that load together near each other:
<directory_tree>
  <!-- Boot files at start -->
  <file name="system.cnf" source="system.cnf"/>
  <file name="game.exe" source="game.exe"/>
  
  <!-- Level 1 data grouped together -->
  <dir name="level1">
    <file name="level1.dat" source="levels/level1.dat"/>
    <file name="level1.geo" source="levels/level1.geo"/>
    <file name="level1.tex" source="levels/level1.tex"/>
    <file name="level1.xa" type="xa" source="audio/level1.xa"/>
  </dir>
  
  <!-- Level 2 data grouped together -->
  <dir name="level2">
    <file name="level2.dat" source="levels/level2.dat"/>
    <file name="level2.geo" source="levels/level2.geo"/>
    <file name="level2.tex" source="levels/level2.tex"/>
    <file name="level2.xa" type="xa" source="audio/level2.xa"/>
  </dir>
</directory_tree>
3

Prioritize Frequently Accessed Files

Place high-priority files early:
<directory_tree>
  <!-- Critical boot files -->
  <file name="system.cnf" source="system.cnf"/>
  <file name="game.exe" source="game.exe"/>
  
  <!-- Shared resources used everywhere -->
  <dir name="common">
    <file name="font.tim" source="common/font.tim"/>
    <file name="ui.dat" source="common/ui.dat"/>
  </dir>
  
  <!-- Less critical data later -->
  <dir name="levels">
    <!-- ... -->
  </dir>
</directory_tree>
4

Generate LBA Log

Create a detailed LBA map:
mkpsxiso myproject.xml -lba output.log
Review the log to verify file placement.
5

Measure and Iterate

Test loading times:
  1. Build ISO with current layout
  2. Measure loading times in game
  3. Adjust file order based on results
  4. Rebuild and test again

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LBA Logging

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Generating LBA Logs

Create a text log: 
mkpsxiso myproject.xml -lba logfile.txt
Or generate a C header file: 
mkpsxiso myproject.xml -lbahead logfile.h

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Log Format

The LBA log contains: 
File: system.cnf
  LBA: 24
  Size: 2048 bytes (1 sectors)
  Timecode: 00:00:24

File: game.exe
  LBA: 25
  Size: 524288 bytes (256 sectors)
  Timecode: 00:00:25

Directory: levels
  LBA: 281

File: levels/level1.dat
  LBA: 282
  Size: 1048576 bytes (512 sectors)
  Timecode: 00:03:82
Information provided:
  • LBA: Sector address
  • Size: File size in bytes and sectors
  • Timecode: MM:SS:FF format for CD timecode
  • Directory locations: LBA of directory records
As of version 2.20, mkpsxiso generates improved LBA logs that are sorted by LBA address rather than filename, making it easier to visualize disc layout.

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Using LBA in Game Code

Include the generated header: 
// logfile.h contains:
#define LEVEL1_LBA 282
#define LEVEL1_SIZE 512

// Use in game code:
CdlLOC loc;
CdIntToPos(LEVEL1_LBA, &loc);
CdControlF(CdlReadN, (u_char*)&loc);
This allows direct LBA access without filename lookups.
Direct LBA access is faster than filename-based access because it skips directory traversal. Use LBA logs to generate header files for performance-critical loading code.

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Log Without Building

Generate logs without creating the ISO: 
mkpsxiso myproject.xml -noisogen -lba output.txt
Useful for:
  • Quick layout analysis
  • Header file generation
  • Planning file placement
  • Documentation

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Advanced Optimization Techniques

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Strategic File Placement

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Inner vs Outer Tracks

CD characteristics:
  • Inner tracks (LBA 0-10000): Faster access, higher density
  • Middle tracks (LBA 10000-200000): Standard performance
  • Outer tracks (LBA 200000+): Slower access, lower density
Place critical files toward the center: 
<directory_tree>
  <!-- Critical files at start (inner tracks) -->
  <file name="system.cnf" source="system.cnf"/>
  <file name="game.exe" source="game.exe"/>
  <dir name="core">
    <file name="engine.dat" source="core/engine.dat"/>
    <file name="common.tim" source="core/common.tim"/>
  </dir>
  
  <!-- Level data in middle -->
  <dir name="levels">
    <!-- ... -->
  </dir>
  
  <!-- Optional content at end (outer tracks) -->
  <dir name="bonus">
    <file name="gallery.dat" source="bonus/gallery.dat"/>
    <file name="extras.dat" source="bonus/extras.dat"/>
  </dir>
</directory_tree>

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Streaming Media Placement

For XA audio and STR video: 
<!-- Place streaming files adjacent to related content -->
<directory_tree>
  <dir name="stage1">
    <!-- Load these together -->
    <file name="stage1.dat" source="levels/stage1.dat"/>
    <file name="stage1_bgm.xa" type="xa" source="audio/stage1.xa"/>
    <file name="intro1.str" type="str" source="video/stage1_intro.str"/>
  </dir>
  
  <dir name="stage2">
    <file name="stage2.dat" source="levels/stage2.dat"/>
    <file name="stage2_bgm.xa" type="xa" source="audio/stage2.xa"/>
    <file name="intro2.str" type="str" source="video/stage2_intro.str"/>
  </dir>
</directory_tree>
Place streaming media immediately after the data files that trigger them. This minimizes seek time when transitioning from loading to streaming.

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Dummy Sectors

Use dummy sectors for strategic spacing: 
<directory_tree>
  <!-- Critical files -->
  <file name="system.cnf" source="system.cnf"/>
  <file name="game.exe" source="game.exe"/>
  
  <!-- Add padding before streaming media -->
  <dummy sectors="10"/>
  
  <!-- Streaming files -->
  <file name="intro.str" type="str" source="video/intro.str"/>
</directory_tree>
Use cases:
  • Align files to specific LBA addresses
  • Create gaps for drive runaway protection
  • Force specific sector boundaries
Large dummy files at the end of the file system can prevent drive runaway (damage from seeking past end of data), but excessive padding wastes disc space.

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Level Loading Optimization

For games with multiple levels: 
<directory_tree>
  <!-- Shared resources first -->
  <dir name="shared">
    <file name="player.dat" source="shared/player.dat"/>
    <file name="enemies.dat" source="shared/enemies.dat"/>
    <file name="ui.dat" source="shared/ui.dat"/>
  </dir>
  
  <!-- Levels in play order -->
  <dir name="level1">
    <file name="data.dat" source="levels/1/data.dat"/>
    <file name="music.xa" type="xa" source="levels/1/music.xa"/>
  </dir>
  
  <dir name="level2">
    <file name="data.dat" source="levels/2/data.dat"/>
    <file name="music.xa" type="xa" source="levels/2/music.xa"/>
  </dir>
  
  <!-- Boss levels after normal levels -->
  <dir name="boss1">
    <file name="data.dat" source="boss/1/data.dat"/>
    <file name="music.xa" type="xa" source="boss/1/music.xa"/>
  </dir>
</directory_tree>
Benefits:
  • Shared resources load once at startup
  • Levels arranged in sequence minimize seeking
  • Boss battles positioned after relevant stages

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Directory Record Order

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Standard Ordering

By default, files are written in XML order: 
<dir name="mydir">
  <file name="file3.dat" source="file3.dat"/>  <!-- LBA 100 -->
  <file name="file1.dat" source="file1.dat"/>  <!-- LBA 150 -->
  <file name="file2.dat" source="file2.dat"/>  <!-- LBA 200 -->
</dir>
Physical order matches XML order (file3, file1, file2).

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Custom Directory Order

For games built with newer Sony mastering tools (2003+): 
<track type="data" new_type="true">
  <directory_tree>
    <dir name="mydir">
      <file name="file1.dat" source="file1.dat" order="1"/>
      <file name="file2.dat" source="file2.dat" order="2"/>
      <file name="file3.dat" source="file3.dat" order="0"/>
    </dir>
  </directory_tree>
</track>
The order attribute:
  • Controls directory record listing order
  • Does NOT change physical LBA
  • Affects how files appear in directory listings
  • Negative values sort before unordered files
  • Positive values sort after unordered files
The order attribute only affects directory record sorting for games using new_type="true". Physical file placement is still controlled by XML order.

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CDDA Track Optimization

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Track Placement

Audio tracks are always after the data track: 
<track type="data">
  <!-- Data track LBA: 0 - 100000 -->
</track>

<!-- Audio tracks start after data -->
<track type="audio" source="track02.wav"/>  <!-- LBA: 100000+ -->
<track type="audio" source="track03.wav"/>  <!-- LBA: 150000+ -->

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DA File Impact

DA files don’t occupy physical space: 
<directory_tree>
  <!-- Physical files -->
  <file name="game.exe" source="game.exe"/>  <!-- LBA: 25 -->
  <file name="level1.dat" source="level1.dat"/>  <!-- LBA: 50 -->
  
  <!-- DA files are just links (no physical space) -->
  <file name="track02.da" trackid="02" type="da"/>  <!-- No LBA -->
  <file name="track03.da" trackid="03" type="da"/>  <!-- No LBA -->
</directory_tree>
DA files must be last to avoid corruption, but don’t affect data layout.

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Measuring Performance

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In-Game Timing

Measure loading times in your game: 
// PlayStation SDK example
int start_time = VSync(-1);
load_level_data();
int end_time = VSync(-1);
int load_time_frames = end_time - start_time;
printf("Load time: %d frames\n", load_time_frames);

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Emulator Analysis

Many emulators show:
  • CD-ROM access count
  • Seek operation count
  • Read speed statistics
  • Access pattern visualization
Use these tools to identify bottlenecks.

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Real Hardware Testing

Test on actual PlayStation hardware:
  • Console CD drives have variable performance
  • Aging drives are slower
  • Seek times vary by disc condition
  • Real hardware is the ultimate test
Test on both emulators and real hardware. Emulator timings may not match actual CD drive performance.

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Best Practices

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General Principles

  1. Group related files: Files loaded together should be adjacent
  2. Critical files first: Boot and core files at start of disc
  3. Sequential access: Arrange files in load order
  4. Minimize seeks: Avoid jumping between distant LBAs
  5. Test iteratively: Measure, adjust, rebuild, repeat

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File Organization

<!-- Optimal structure -->
<directory_tree>
  <!-- 1. Boot files (LBA ~24) -->
  <file name="system.cnf" source="system.cnf"/>
  <file name="game.exe" source="game.exe"/>
  
  <!-- 2. Shared/common resources -->
  <dir name="common">
    <file name="font.tim" source="common/font.tim"/>
    <file name="ui.dat" source="common/ui.dat"/>
  </dir>
  
  <!-- 3. Level data in play order -->
  <dir name="level1">
    <file name="level1.dat" source="levels/1.dat"/>
    <file name="level1.xa" type="xa" source="audio/1.xa"/>
  </dir>
  
  <dir name="level2">
    <file name="level2.dat" source="levels/2.dat"/>
    <file name="level2.xa" type="xa" source="audio/2.xa"/>
  </dir>
  
  <!-- 4. Optional/bonus content -->
  <dir name="bonus">
    <file name="gallery.dat" source="bonus/gallery.dat"/>
  </dir>
  
  <!-- 5. DA files last -->
  <file name="track02.da" trackid="02" type="da"/>
  
  <!-- 6. End padding for drive protection -->
  <dummy sectors="1024"/>
</directory_tree>

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Common Pitfalls

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Random File Order

Avoid: 
<!-- Bad: Random order -->
<directory_tree>
  <file name="level3.dat" source="level3.dat"/>
  <file name="level1.dat" source="level1.dat"/>
  <file name="menu.dat" source="menu.dat"/>
  <file name="level2.dat" source="level2.dat"/>
</directory_tree>
This causes excessive seeking when loading levels in sequence. Avoid: 
<!-- Bad: Related files far apart -->
<directory_tree>
  <file name="level1.dat" source="level1.dat"/>  <!-- LBA 100 -->
  <!-- Many other files -->
  <file name="level2.dat" source="level2.dat"/>  <!-- LBA 5000 -->
  <!-- More files -->
  <file name="level1.xa" type="xa" source="audio/level1.xa"/>  <!-- LBA 10000 -->
</directory_tree>
Loading level1 requires seeking from LBA 100 to 10000.

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No Planning

Simply adding files without strategy results in poor performance:
  • Boot times are slow
  • Level transitions have long loads
  • Streaming media stutters

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Next Steps

Optimize your disc layout:
  • Use Building ISOs with optimized file order
  • Generate LBA logs for analysis
  • Place XA Audio and STR Video strategically
  • Test on real hardware for accurate performance measurement

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