What is the stream.ini file for in GTA: SA and how do I mod it?

Question

I'm wondering what is the stream.ini file for in Grand Theft Auto: San Andreas
Also there are the following parameters in the file.

memory      13500
devkit_memory   13500
vehicles    12
pe_lightchangerate  0.0005
pe_lightingbasecap  0.35
pe_lightingbasemult 0.5
pe_leftx    16
pe_topy     16
pe_rightx   16
pe_bottomy  16
dontbuildpaths

What are these for?

Answer 1

http://gtaforums.com/topic/194134-streamini/

If you open stream.ini, you'll see a tag indicating how much memory is allocated to streaming content

I doubt you can achieve anything else than performance improvements by modifying the file. If you want to raise or remove some limits entirely, use Open Limit Adjuster mod. Variables:

 Buildings
 Buildings on the building pool
 Building is anything placed by a IPL that is not a object (see Dummys or Objects to see what is a object)

 Peds
 Peds on the peds pool
 Note this does not increase the amount of peds roaming, but increases the maximum number of peds can be created

 Vehicles
Vehicles on the vehicles pool
Note this does not increase the amount of vehicles roaming, but increases the maximum number of vehicles can be created

 Objects
Dynamic objects (i.e. registed in objects.dat) near/visible to the player
See also: Dummys

 Dummys
Dynamic objects (i.e. registed in objects.dat) spawned at once in the entire world

 PedIntelligence
Ped AI instances
**MUST** be the same value as Peds

 ColModel [CanBeUnlimited]
Collision models loaded at once
Notice this is not the same as one .col file, .col files might be collision archives which contain many ColModels.

 PtrNodeSingle [CanBeUnlimited]
Nodes for the pool of singly linked lists
Directly related to the amount of entities spawned in the world and values stored in quad trees.

 PtrNodeDouble [CanBeUnlimited]
Nodes for the pool of double linked lists
Directly related to the amount of entities spawned in the world

 PtrNode
Mix of PtrNodeSingle and PtrNodeDouble (see PtrNodeSingle and PtrNodeDouble)

 EntryInfoNode [CanBeUnlimited]
Directly related to the amount of collidable entities spawned in the world

 Task [CanBeUnlimited]
Running pedestrian tasks around the world

 Event [CanBeUnlimited]
Events notification around the world (vehicles collided, etc)

 PointRoute [CanBeUnlimited]
Related to AI routes (see scm command 05D7)

 PatrolRoute [CanBeUnlimited]
Related to AI patrol routes (see scm command 0755)

 NodeRoute [CanBeUnlimited]
Related to dynamic AI routes to go somewhere (for example, the command 05F5)

 TaskAllocator [CanBeUnlimited]
Allocator of tasks to organized group of peds

 PedAttractors [CanBeUnlimited]
Peds attracted to specific objects (e.g. ped using a cassino machine)

 VehicleStructs [CanBeUnlimited]
Loaded vehicles models information.

 Treadables
Animated buildings?

 AudioScriptObj
Script sounds (see scm command 018D)

 MatrixList [CanBeUnlimited]
Pool of transformation matrices, directly related to the amount of physical objects in the world

 AlphaEntityList [CanBeUnlimited]
List of entities (non-vehicle) to be rendered that contains alpha components 

 VisibleEntityPtrs [CanBeUnlimited]
List of visible non-lod entities

 VisibleLodPtrs [CanBeUnlimited]
List of visible lod entities

 OutsideWorldWaterBlocks
Amount of blocks outside the world boundaries to be rendered 
Fixes water flickering outside world bondaries

 StreamingObjectInstancesList
List of streamed in entities RwObjects (dff models)
Fixes buildings flickering when seeing too many of them

 AtomicModels [CanBeUnlimited]
Maximum amount of object definitions that aren't breakable (http://www.gtamodding.com/index.php?title=OBJS)

 DamageAtomicModels [CanBeUnlimited]
Maximum amount of object definitions that are breakable (http://www.gtamodding.com/index.php?title=OBJS)

 TimeModels [CanBeUnlimited]
Maximum amount of timed object definitions (http://www.gtamodding.com/index.php?title=TOBJ)

 ClumpModels [CanBeUnlimited]
Maximum amount of hierarchical object definitions (http://www.gtamodding.com/wiki/HIER and http://www.gtamodding.com/wiki/ANIM)

 VehicleModels [CanBeUnlimited]
Maximum amount of vehicle definitions (http://www.gtamodding.com/wiki/CARS_(IDE_Section))

 PedModels [CanBeUnlimited]
Maximum amount of ped definitions (http://www.gtamodding.com/wiki/PEDS)

 WeaponModels [CanBeUnlimited]
Maximum amount of weapon definitions (http://www.gtamodding.com/wiki/WEAP)

 EntitiesPerIpl [CanBeUnlimited]
Maximum amount of instantiated entities (in INST section) from a single IPL file.

 EntityIpl [CanBeUnlimited]
Maximum number of IPL files that creates entities.

 StaticShadows
Maximum amount of static shadows

 Coronas
Maximum amount of coronas

 ScriptSearchLights
Maximum amount of searchlights that can be created with opcode 06B1

 FrameLimit
By default this is set to 30, which is actually 25fps. For 60fps, the value is 105.

 MemoryAvailable
Streaming memory available for streamed resources