Vgm ptch

General VGM patching utility; allows editing the VGM header (chip clocks/chip settings), checking/fixing VGMs and stripping chips/channels.

Please note: vgm_ptch always edits the original file(s). It doesn't create new files, so you probably want to create your own backups first.

Help

Usage: vgm_ptch [-command1] [-command2] file1.vgm file2.vgz

General Commands:
    -Help         Show this help
    -ChipCmdList  List all supported chips with SetHzxx command
    -StripList    List all supported chips and channels for the Stip command

Patching Commands:
Command format: -command:value
    -SetVer       Set Header-Version (e.g. 1.51, don't use with v1.00-1.10)
    -UpdateVer    Update Header-Version (additional changes if neccessary)
    -MinHeader    Minimize Header Size (v1.50+, useful after stripping chips)
    -MinVer       Minimize VGM Version (v1.50+, useful after stripping chips)
    -SetRate      Sets the Playback rate (v1.01+)
    -SetHzxxx     Sets the xxx's chip clock (see -ChipCmdList for details)
    -SetLoopMod   Set the Loop Modifier (Format: *2, /2.0, 0x20)
    -SetLoopBase  Set the Loop Base (-128 to 127)
    -SetVolMod    Set the Volume Modifier (Format: 1.0, 0x00)

Commands to check the lengths (total, loop) and offsets (EOF, loop, GD3):
    -Check        asks for correction
    -CheckR       read only mode
    -CheckL       autofix mode, recalculates lengths
    -CheckO       like above, but tries to relocate loop offset

    -Strip        Strip the data of a chip and/or channel
                   Format: -Strip:Chip[-Num][:Ch,Ch,...];Chip
                   e.g.: -Strip:PSG:0,1,2,Noise,Stereo;YM2151
                         -Strip:YM2612-0;OKIM6295-1
                   Note: Stripping does not (yet) work with all chips.

                   Tip: Stripping without commands optimizes the delays.

Command names are case insensitive.

Stripping unused chips from a VGM

First use vgm_cnt on it to see if there really are any unused chips. Unused chips will have 0 for both Commands and Notes.

If you do find an unused chip, you can strip it with the Strip option, specifying the chip (and channel, if necessary), such as like the following examples.

vgm_ptch -Strip:AY8910-0 file.vgm; strip first AY chip
vgm_ptch -Strip:AY8910-1 file.vgm; strip second AY chip
vgm_ptch -strip:ym2151 "04 Credit SFX.vgm"; strip YM2151