I'm trying to run HLSL Pixel Shaders with DirectX 9 where I feed a texture in, run the HLSL code and copy the resulting texture back from memory. I think I'm getting pretty close, although a LOT of time could be wasted trying to figure out the details. It's kind of pointless to study the whole DirectX SDK just for doing this basic task; I just want to get it done. Could you take a look at this code, give pointers as to what's missing, and answer a few questions?

Fist here are my questions, then followed by the code I have so far

  1. Am I on the right track?
  2. Am I better to pre-compile the shaders with fxc.exe or compile them on-the-fly? If I pre-compile, how do I load a pre-compiled shader?
  3. In Diff.hlsl shader below, certain data are defined with "register" (sampler s0 : register(s0);) What are those and how do I configure them?
  4. Can HLSL shaders alter the size of the texture? If so, how do I get the size back to parse the texture data accordingly?
  5. How do I configure the parameters and run the shader?
  6. Will I run into performance issues running this code? It gets called to process a video with AviSynth, where GetFrame gets called for each video frame. 8 instances will run on 8 parallel threads.
  7. Anything else I should know?

I'm copying the texture data back and forth between AviSynth and the shader texture. The only difference in the memory structure is that AviSynth has a padding to the right of each line which has to be removed when copying to the shader and added back when copying back to AviSynth.

Here are some of the shaders I'm trying to run



Here's my code: Shader.cpp

#include "Shader.h"

Shader::Shader(PClip _child, IScriptEnvironment* env) :
GenericVideoFilter(_child) {
    if (vi.IsPlanar() || !vi.IsRGB32())
        env->ThrowError("Source must be float-precision RGB");


void Shader::InitDirectX(IScriptEnvironment* env) {
    dx = Direct3DCreate9(D3D_SDK_VERSION);

    // Initialize DirectX9
    dx->GetAdapterDisplayMode(D3DADAPTER_DEFAULT, &dxMode);
    ZeroMemory(&dxSettings, sizeof(dxSettings));
    dxSettings.Windowed = TRUE;
    dxSettings.SwapEffect = D3DSWAPEFFECT_DISCARD;
    dxSettings.BackBufferFormat = dxMode.Format;
    dxSettings.EnableAutoDepthStencil = TRUE;
    dxSettings.AutoDepthStencilFormat = D3DFMT_D16;
    dxSettings.PresentationInterval = D3DPRESENT_INTERVAL_IMMEDIATE;
    dx->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_NULLREF, NULL, NULL, &dxSettings, &dxDevice);

    // Create pixel shader
    LPD3DXBUFFER dxShaderCode;
    LPD3DXBUFFER errors = NULL;
    if (FAILED(D3DXCompileShaderFromFile("F:\AVSMeter\MPDN_Extensions-master\Extensions\RenderScripts\SuperRes\Diff.hlsl", NULL, NULL, "main", "ps_3_0", 0, &dxShaderCode, &errors, &dxShaderConstantTable))) {
        env->ThrowError((const char*)errors->GetBufferPointer());
    dxDevice->CreatePixelShader((DWORD*)dxShaderCode->GetBufferPointer(), &dxShader);

Shader::~Shader() {
    if (dxDevice != NULL) {
        dxDevice = NULL;
    if (dx != NULL) {
        dx = NULL;
    if (dxShader != NULL) {
        dxShader = NULL;
    if (dxShaderConstantTable != NULL) {
        dxShaderConstantTable = NULL;

PVideoFrame __stdcall Shader::GetFrame(int n, IScriptEnvironment* env) {
    PVideoFrame src = child->GetFrame(n, env);

    // Copy data to texture buffer
    unsigned char* textureBuffer = (unsigned char*)malloc(vi.width * vi.height * 16);
    CopyToTexture(src->GetReadPtr(), src->GetPitch(), textureBuffer);

    // Create texture
    HANDLE* dxTextureHandle = (HANDLE*)textureBuffer;
    dxDevice->CreateTexture(vi.width, vi.height, 1, 0, D3DFMT_A32B32G32R32F, D3DPOOL_SYSTEMMEM, &dxTexture, dxTextureHandle);

    // Run shader on texture
    dxDevice->SetTexture(0, dxTexture);

    // Copy data back to frame
    CopyFromTexture(textureBuffer, src->GetWritePtr(), src->GetPitch());

    // Release texture
    dxTexture = NULL;
    return src;

void Shader::CopyToTexture(const byte* src, int srcPitch, unsigned char* dst) {
    for (int i = 0; i < vi.height; i++) {
        memcpy(dst, src, vi.width * pixelSize);
        src += srcPitch;
        dst += vi.width * pixelSize;

void Shader::CopyFromTexture(const byte* src, unsigned char* dst, int dstPitch) {
    for (int i = 0; i < vi.height; i++) {
        memcpy(dst, src, vi.width * pixelSize);
        src += vi.width * pixelSize;
        dst += dstPitch;


#include <windows.h>
#include <d3d9.h>
#include <d3dx9.h>
#include <cstdio>       //needed by OutputDebugString()
#include "avisynth.h"   //version 5, AviSynth 2.6 +

class Shader : public GenericVideoFilter {
    Shader(PClip _child, IScriptEnvironment* env);
    PVideoFrame __stdcall GetFrame(int n, IScriptEnvironment* env);
    void InitDirectX(IScriptEnvironment* env);
    void Shader::CopyToTexture(const byte*, int srcPitch, unsigned char* dst);
    void Shader::CopyFromTexture(const byte* src, unsigned char* dst, int dstPitch);
    LPDIRECT3D9 dx = NULL;
    LPD3DXCONSTANTTABLE dxShaderConstantTable = NULL;
    const int precision = 4;
    const int pixelSize = 16;
  • \$\begingroup\$ A few notes: * the DirectX SDK and DirectX 9 are both deprecated. See MSDN. * Full-screen exclusive mode makes debugging more difficult, so focus on windowed mode until you get everything working. * You must check the HRESULT of every function that returns it for failure. You aren't doing that. \$\endgroup\$ Jul 14, 2015 at 3:13
  • \$\begingroup\$ Your use of CreateTexture's pSharedHandle doesn't look valid. If you are creating the texture as D3DPOOL_SYSTEM, you cant' render with it. You need to use Lock and respect the returned pitch which you are incorrectly assuming is always byte aligned. \$\endgroup\$ Jul 14, 2015 at 3:15
  • \$\begingroup\$ Have you tried to enable the DEBUG device? Note that DirectX 9 debug device is not supported on Windows 8.0 or later. \$\endgroup\$ Jul 14, 2015 at 3:17
  • \$\begingroup\$ I don't want to render anything to the screen. I simply run the shader on the texture data and then read the data back from memory. And I haven't run this code yet, it's just approaching a prototype. Even if DX9 is deprecated, I don't see the point of adding DX10 or DX11 as a requirement for doing something so basic. To load the texture from a memory pointer, I need to use D3DPOOL_SYSTEMMEM and I don't render anything to the screen. The pitch can have padding on each line in the same way as AviSynth frames? How does the texture know the pitch of the memory data I give it? \$\endgroup\$ Jul 14, 2015 at 20:59
  • \$\begingroup\$ The comments so far are mostly about technical details. I'm more asking about the higher-level picture of how it needs to be structured. \$\endgroup\$ Jul 14, 2015 at 23:35

1 Answer 1


Since this question has been viewed 1000 times, I might as well post a follow-up.

This is the code I ended up with, processing Avisynth video scripts through pixel shaders. https://github.com/mysteryx93/avisynthshader

  1. I'm precompiling shaders because some shaders (Bicubic.hlsl) take a long time to compile, and you get all the errors at compile-time.

  2. If I remember correctly, shader output size is set to the size of the output texture we're rendering to.

  3. The performance bottleneck is in transfering GPU memory back to the CPU, as graphic cards are not designed for that. I got best performance by lining up all the shaders into a processing chain, and transfer only the result after processing them all at once. I'm also getting best performance by running 8 threads on 2 DirectX engines.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .