Though this long article has more lines than the encoder library itself, this is a very simple and easy to read and understand article. If you have read my other articles before, you will be comfortable to know I do not write complicated stuff.
Table of Contents
Requirements
Video Encoder
Visual C++ 2015/2017 Windows 7/8/10
OpenGL Renderer
SDL2 SDL2 Image GLEW GLM Tiny OBJ loader Zlib
All the OpenGL Renderer required libraries are included in the repository. The focus is on Video Encoder .
I just completed my (closed-source) photo slideshow application, Mandy Frenzy, based on the video encoder featured in this article. Below is the video encoded from it. You can download my slideshow application from here or visit its home page .
VIDEO
I worked on this video encoder while writing my Windows Store App, Mandy Frenzy, a photo slideshow app for ladies. (Update: Mandy Frenzy has been converted from C# WPF to C++ MFC due to perf issues on WPF) Right now, I am feeling burnt out so I am taking a short hiatus. Meanwhile, I am writing a series of short articles as a way to document this app. This video encoder is a header file only (H264Writer.h ), based on Microsoft Media Foundation, not the old DirectShow as Microsoft did not expose the H264 and HEVC codec on DirectShow. It is tested on Windows 10. It should work fine on Windows 7/8 as well. Do let me know if you encounter any problem on those OSes. Windows 10 used to come bundled with HEVC codec. For unknown reasons, MS has taken it out in Windows 10 Fall Creators Update for the **new** Windows 10 installation and put it up for purchase for $1.50 in the Microsoft Store. In the section below, some screenshots will show encoding artifacts present in MS HEVC video. HEVC quality issues are fixed with hardware acceleration.
What Are the Pros and Cons of This Encoder Over FFmpeg?
FFmpeg is GPL and so you may not be concerned if you just want to encode the output of your personal renderer. For my freemium app, I prefer to steer clear of the licensing issues. How hobbyists usually encode their frames with FFmpeg is to save all the frames in HDD first which limits the number of frames and also directly impacted video duration that can be saved depending on the free HDD space. The extra step of saving and opening the files has negative impact of the encoding speed. Of course, tight integration with FFmpeg code may eliminate the frame saving part. On the other hand, this encoder reads RGB values from the framebuffer provided. The downside is it is not portable and only works on Windows 7/8/10.
3 Rendering Modes
The same OpenGL renderer can be compiled into three modes: normal OpenGL display mode, Video Encoder mode and Emscripten mode. The latter two's code sections are respectively guarded by VIDEO_ENCODER and EMSCRIPTEN macros. You can, by all means, use your own renderer with the video encoder. The default OpenGL renderer is just provided to show a working demo.
The documentation is divided into three main sections. The first section is get the demo up and running and on how to modify the parameters. The second section is on how to integrate it with your OpenGL framework. The demo uses a renderer framework taught in Paul Varcholik's OpenGL Essentials LiveLessons . The original source code used GLFW and is based on OpenGL 4.4: I converted his framework to use SDL and downgrade to OpenGL 2.0. The decision is based on the lowest denominator of what WebGL and Emscripten can support. A tutorial on how to integrate with DirectX will come later. In theory, this video encoder should integrate well with other graphics API like Vulkan, after all, all it needs is to be supplied with a video buffer and some synchronization in tandem to perform its work. The third section is on the explanation of the internals of the video encoder which you can skip if you are not into the encoder internals and implementation. And the last section explains the Emscripten part required to compile into asm.js or Webassembly.
Spaceship Video
Spaceship Video on Youtube
All the required libraries are included in the repository. The required DLLs are copied automatically to the Release or Debug folder for Win32 post builds. x64 build is unbuildable due to the inability to find a x64 zlib lib/dll on the web; this is a linking problem that lies with the OpenGL renderer, not video encoder.
To see the OpenGL demo, open up SDL_App.sln in Visual Studio and build the SDL_App project.
To run the video encoding demo, open up H264SinkWriter.cpp and in the main function, modify the configFile, musicFile and videoFile to the paths on your machine. configFile is found in the $(SolutionDir)SDL_App folder. musicFile should be a mp3 file and if it is left blank, the final video shall not have music. videoFile is the encoded video. You can specify HVEC(aka H265) instead of H264 in the 4th parameter. HVEC is having some encoding issues where the colors bleed (See screenshots below.)
std::wstring configFile
(L" D:\\GitHub\\video_encoder_for_ogl_dx\\SDL_App\\SDL_App\\config.txt" );
std::wstring musicFile(L" D:\\FMA.mp3" );
std::wstring videoFile(L" C:\\Users\\shaov\\Documents\\video.mp4" );
H264Writer writer(musicFile.c_str(), configFile.c_str(),
videoFile.c_str(), VideoCodec::H264);
if (writer.IsValid())
{
if (writer.Process())
{
printf(" Video written successfully!\n" );
return 0 ;
}
}
printf(" Video write failed!\n" );
getchar();The typical config.txt is to facilitate passing of information to OpenGL renderer, has nothing to do with video encoder. If your renderer can get the information about the video it is about to encode, then just pass a dummy config.txt . The contents of a typical config.txt is shown below:
ScreenWidth=800
ScreenHeight=600
LogPath=C:\Users\shaov\Documents\log.txt
FPS=60
Now the demo does not handle aspect ratio automatically and it always sticks with 4:3 ratio. If you enter anything which is 16:9, or wider than 4:3, in screen width and height, your video will look stretched. FPS entry is for the integer number of frames per second; there is no way to enter a decimal number like 29.7777.
The demo would only encode 5 seconds of the video. Change duration in RenderingScene::Draw function.
void RenderingScene::Draw(const SceneTime& gameTime)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
float grey = 35 .0f / 255 .0f ;
glClearColor(grey, grey, grey, 1 .0f );
Scene::Draw(gameTime);
SDL_GL_SwapWindow(mWindow);
#ifdef VIDEO_ENCODER
static GLfloat start_time = gameTime.TotalGameTime();
GLfloat elapsed_time = gameTime.TotalGameTime() - start_time;
if (elapsed_time > 5 .0f )
{
Scene::setVideoEnded();
}
#endif
}You have to experiment to find out the optimal bitrate that can encode a good quality video.
enum class VideoCodec
{
H264,
HVEC
};
H264Writer(const wchar_t * mp3_file, const wchar_t * src_file, const wchar_t * dest_file,
VideoCodec codec, UINT32 bitrate = 4000000 ) :
{...}To run the demo executable by itself, you need to copy the config.txt , Images and Models folders to the Release/Debug folder. The SDL2 DLLs would have already copied during post build.
By default, demo displays a rotating UFO saucer, to display other 3D model, just uncomment the other lines in CreateComponents().
void RenderingScene::CreateComponents()
{
mCamera = std::unique_ptr < FirstPersonCamera> (new
FirstPersonCamera(*this , 45 .0f , 1 .0f / 0 .75f , 0 .01f , 100 .0f ));
mComponents.push_back(mCamera.get());
mServices.AddService(Camera::TypeIdClass(), mCamera.get());
try
{
mUFOSpecularModel = std::unique_ptr < SpecularModel>
(new SpecularModel(*this , *mCamera,
" UFOSaucer3.jpg" , " UFOSaucer.obj.txt.zip" , " UFOSaucer.mtl.txt" ));
mComponents.push_back(mUFOSpecularModel.get());
}
catch (SceneException& e)
{
char buf[1000 ];
SPRINTF(buf, " ModelEffect exception:%s" , e.what());
gLogger.DebugPrint(buf);
}
#ifdef __EMSCRIPTEN__
gDownloadSingleton.DownloadAllNow();
#endif
}H264 Video of Mandy Frenzy
H264 Video on Youtube
HEVC Video (Artifacts) of Mandy Frenzy
HEVC Video on Youtube
Update : The HEVC quality problem is fixed with h/w acceleration.
As you can see, the sinewave artifacts in HEVC, not present in H264. Increasing the bitrate solves the problem at the expense of larger file size. By the way, the sinewave is rendered by triangles, not lines and not by fragment shaders. Reason being lines are usually implemented as 1 pixel wide in OpenGL ES 2.0. Using triangles allows me to control the width/height.
This section teaches the modification needed to integrate the video encoder into your renderer.
The fastest way to find all the encoding related code is to search for VIDEO_ENCODER macro in the source code. The encoder requires you to implement two global functions: check_config_file and encoder_start. See their declarations below. encoder_start is called in the worker thread.
extern int check_config_file(const wchar_t * file, int * width, int * height, int * fps);
extern int encoder_start(UINT** pixels, HANDLE evtRequest, HANDLE evtReply,
HANDLE evtExit, HANDLE evtVideoEnded, const WCHAR* szUrl);They, in turn, called their DLL counterparts implemented in the Program.cpp .
int check_config_file(const wchar_t * file, int * width, int * height, int * fps)
{
return ::check_project_file(file, width, height, fps);
}
int encoder_start(UINT** pixels, HANDLE evtRequest, HANDLE evtReply,
HANDLE evtExit, HANDLE evtVideoEnded, const WCHAR* szUrl)
{
return ::encoder_main(pixels, evtRequest, evtReply, evtExit,
evtVideoEnded, szUrl);
}check_project_file requires you to pass the screen width, height and FPS information from the file which is config.txt . In reality, you can just open any file which can provide you with this information, so implementation of check_project_file is unimportant. Let's see how encoder_main is implemented.
SDL_APP_DLL_API int WINAPI check_project_file(const wchar_t * file, int * width,
int * height, int * fps)
{
ConfigSingleton config;
const std::string afile = toAString(file);
bool ret = config.LoadConfigFile(afile);
if (ret)
{
*width = config.GetScreenWidth();
*height = config.GetScreenHeight();
*fps = config.GetFPS();
}
return ret;
}
SDL_APP_DLL_API int WINAPI encoder_main(UINT** pixels, HANDLE evtRequest,
HANDLE evtReply, HANDLE evtExit,
HANDLE evtVideoEnded, const WCHAR* szUrl)
{
try
{
const std::string& config_file = toAString(szUrl);
gConfigSingleton.OpenFile(config_file.c_str(),
Library::DownloadableComponent::FileType::INI_FILE);
if (gConfigSingleton.IsLoadSuccess() == false )
{
gLogger.Log(" gConfigSingleton.IsLoadSuccess() failed! See log!" );
return 1 ;
}
Texture::setScreenDim(gConfigSingleton.GetScreenWidth(),
gConfigSingleton.GetScreenHeight());
std::unique_ptr < RenderingScene>
renderingScene(new RenderingScene(L" Photo Montage" ,
gConfigSingleton.GetScreenWidth(), gConfigSingleton.GetScreenHeight()));
renderingScene-> initVideoEncoder(pixels, evtRequest, evtReply, evtExit,
evtVideoEnded, gConfigSingleton.GetFPS());
renderingScene-> Run();
}
catch (SceneException& ex)
{
gLogger.Log(ex.GetError().c_str());
}
catch (std::exception& ex)
{
gLogger.Log(ex.what());
}
return 0 ;
}
encoder_main is very similar to WinMain except it calls initVideoEncoder function to hand over the parameters. This is how initVideoEncoder is implemented: it just zero initialized some members and saved the parameters inside its members. These HANDLE arguments are already initialized inside the H264Writer constructor. setTimeQuandant() is to set the time increment for every frame, for example, if FPS is 30, then the time increment should be 33.3, irregardless of actual time passed. You wouldn't want varying time rate for your video encoding.
void Scene::initVideoEncoder(UINT** pixels, HANDLE evtRequest, HANDLE evtReply,
HANDLE evtExit, HANDLE evtVideoEnded, int fps)
{
mTexture = 0 ;
mRenderBuffer = 0 ;
mDepthBuffer = 0 ;
mMultisampleTexture = 0 ;
mPixels = pixels;
mPixelBuffer = nullptr ;
mEvtRequest = evtRequest;
mEvtReply = evtReply;
mEvtExit = evtExit;
mEvtVideoEnded = evtVideoEnded;
mGameClock.setTimeQuandant((1000 .0f/(float )fps)/1000.0f );
}This is how encoder_start is called in the worker thread started by H264Writer.
DWORD WINAPI ThreadOpenGLProc(LPVOID pParam)
{
H264Writer* pWriter = (H264Writer*)(pParam);
return ::encoder_start((UINT**)(
pWriter-> GetImagePtr()),
pWriter-> GetRequestEvent(),
pWriter-> GetReplyEvent(),
pWriter-> GetExitEvent(),
pWriter-> GetVideoEndedEvent(),
pWriter-> GetUrl().c_str());
}
In our OpenGL renderer, we need to create RenderBuffer for our renderer to draw on.
void Scene::CreateFBO()
{
#ifdef VIDEO_ENCODER
mPixelBuffer = new unsigned int [mScreenWidth*mScreenHeight];
glGenTextures(1 , &mMultisampleTexture);
glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, mMultisampleTexture);
glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 4 ,
GL_RGBA, mScreenWidth, mScreenHeight, GL_TRUE);
glGenRenderbuffers(1 , &mRenderBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, mRenderBuffer);
glRenderbufferStorageMultisample(GL_RENDERBUFFER, 16 , GL_RGBA8,
mScreenWidth, mScreenHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
GL_RENDERBUFFER, mRenderBuffer);
glGenRenderbuffers(1 , &mDepthBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, mDepthBuffer);
glRenderbufferStorageMultisample(GL_RENDERBUFFER, 16 ,
GL_DEPTH24_STENCIL8, mScreenWidth, mScreenHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
GL_RENDERBUFFER, mDepthBuffer);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT,
GL_RENDERBUFFER, mDepthBuffer);
GLuint mTexture = 0 ;
glGenTextures(1 , &mTexture);
glBindTexture(GL_TEXTURE_2D, mTexture);
unsigned int dim = determineMinDim(mScreenWidth, mScreenHeight);
unsigned int * pixels = new unsigned int [dim * dim];
glTexImage2D(GL_TEXTURE_2D, 0 , GL_RGBA, dim, dim, 0 ,
GL_RGBA, GL_UNSIGNED_BYTE, pixels);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
delete [] pixels;
pixels = NULL;
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
GL_TEXTURE_2D, mTexture, 0 );
glEnable(GL_MULTISAMPLE);
if (GL_FRAMEBUFFER_COMPLETE == glCheckFramebufferStatus(GL_FRAMEBUFFER))
{
OutputDebugStringA(" FBO status: Complete!\n" );
}
else
{
OutputDebugStringA(" FBO status: Not complete!\n" );
}
#endif // VIDEO_ENCODER
}determineMinDim() used in the above function is implemented in this way because we need a square texture to power of 2.
#ifdef VIDEO_ENCODER
unsigned int Scene::determineMinDim(unsigned int width, unsigned int height)
{
unsigned int dim = width;
if (height > width)
dim = height;
unsigned int min_dim = 32 ;
if (dim > 32 && dim < = 64 )
min_dim = 64 ;
else if (dim > 64 && dim < = 128 )
min_dim = 128 ;
else if (dim > 128 && dim < = 256 )
min_dim = 256 ;
else if (dim > 256 && dim < = 512 )
min_dim = 512 ;
else if (dim > 512 && dim < = 1024 )
min_dim = 1024 ;
else if (dim > 1024 && dim < = 2048 )
min_dim = 2048 ;
else if (dim > 2048 && dim < = 4096 )
min_dim = 4096 ;
else
min_dim = 4096 ;
return min_dim;
}
#endif // VIDEO_ENCODER Lastly, we need to read the rendered buffer with glReadPixels. The code wait on mEvtRequest and mEvtExit. mEvtRequest is signaled when the encoding thread requests for new frame. Whereas the mEvtExit is signaled during exit. After copying the buffer to mPixels, mEvtReply is signaled to encoding thread that mPixels is ready.
void Scene::ReadBuffer(bool& quit)
{
#ifdef VIDEO_ENCODER
glReadBuffer(GL_COLOR_ATTACHMENT0);
glReadPixels(0 , 0 , mScreenWidth, mScreenHeight,
GL_BGRA_EXT, GL_UNSIGNED_BYTE, mPixelBuffer);
HANDLE arrHandle[2 ];
arrHandle[0 ] = mEvtRequest;
arrHandle[1 ] = mEvtExit;
DWORD dwEvt = WaitForMultipleObjects(2 , arrHandle, FALSE, INFINITE);
if (dwEvt == WAIT_OBJECT_0 + 1 )
{
quit = true ;
}
while (*mPixels == NULL) { Sleep(100 ); }
if (*mPixels)
memcpy(*mPixels, mPixelBuffer, mScreenWidth*mScreenHeight*sizeof (unsigned int ));
SetEvent(mEvtReply);
#endif // VIDEO_ENCODER
}This is how CreateFBO() and ReadBuffer() are called in my Render(). CreateFBO() and ReadBuffer() are empty when not compiled in VIDEO_ENCODER mode.
void Scene::Render(bool& quit)
{
static bool all_init = false ;
if (all_init == false )
{
if (IsAllReady())
{
CreateFBO();
Initialize();
if (IsAllInitialized())
{
all_init = true ;
mGameClock.Reset();
}
}
}
if (all_init)
{
mGameClock.SetPause(mPaused);
if (mPaused == false )
{
mGameClock.UpdateGameTime(mGameTime);
}
Update(mGameTime);
Draw(mGameTime);
ReadBuffer(quit);
}
}Media Foundation provides three methods to writing a video encoder:
Media Session Transcoder API SinkWriter
All these methods come with their pros and cons. They range from the most difficult/control to ease to use but with little control.
The first method is to construct your own media session which is a topology. This approach has the most flexible/control, on the other hand, it has the highest difficulty reserved for MF professional because you have to find Media Source, Transform and Media Sink and connect them together. However, you have the flexibility to choose your transform vendor. For those who are not familiar: Media Sources are used to demultiplex the source file. Media Foundation Transforms are used to decode and encode streams. Media Sinks are used to multiplex the streams and write the multiplexed stream to a file or network. There is one downside to using this method, because you have to write and register your Media Source DLL on user computer. In most cases, this does not present a problem. But my UWP app's installation and operation is sandboxed, meaning all the file saves and registry writes are redirected to unknown location. I am not sure if MF can find and instantiate my Media Source DLL if all it does is only look at global registry and folders.
The second method is using a Transcoding API which makes it easier to construct the media session for you with the most sensible options chosen for you. This method is out of question for me because I am not transcoding a video file into another format.
The third method, SinkWriter, is the most simple to integrate with your OpenGL render. One very big downside is it always chooses Microsoft **software** transform even when there are hardware accelerated ones available on your system, like in my case, I have the Intel and NVidia H264 h/w encoders(See below). This is the approach I chose. I was mislead by the book: the third method can also make use of hardware acceleration in latest 1.0.3 version.
H/w encoder
Video Encoder: Intel Quick Sync Video H.264 Encoder MFT
Video Encoder: NVIDIA H.264 Encoder MFT
S/w encoder
Video Encoder: H264 Encoder MFT
Enumeration of the encoders is done with EnumVideoEncoder function (shown below).
std::vector < std::wstring > encoders;
if (H264Writer::EnumVideoEncoder(encoders, Processing::Software, VideoCodec::H264))
{
for (size_t i = 0 ; i < encoders.size(); ++i)
{
printf(" Video Encoder: %S\n" , encoders[i].c_str());
}
}
else
{
printf(" H264Writer::EnumVideoEncoder failed!\n" );
}Work shall continue on the first method to utilize H/w encoder.
To use this header only library, just include H264Writer.h inside your C++ source code. And remember to implement the two functions below. file can be any format. check_config_file shall return the frame dimensions and frame rate per second.
In the integration section above, there is an example of how encoder_start() is implemented by encoder_main().
extern int check_config_file(const wchar_t * file, int * width, int * height, int * fps);
extern int encoder_start(UINT** pixels, HANDLE evtRequest,
HANDLE evtReply, HANDLE evtExit, HANDLE evtVideoEnded, const WCHAR* szUrl);In H264Writer only constructor, as you can see, it initializes a bunch of members to the default value. There is m_hThread which runs the OpenGL Win32 loop. One characteristic of this encoder is the OpenGL window is running in the foreground. The user will see that window. If your application requirement is not to show user the windows, you have to create a invisible window in encoder_main(). m_evtRequest is for requesting frame from the OpenGL thread, m_evtReply is used by OpenGL to tell the frame is copied and ready. m_evtExit is signaled in case user close the window before video encoding is completed. m_evtVideoEnded is signalled by Scene::setVideoEnded() in the Draw() function.
H264Writer(const wchar_t * mp3_file, const wchar_t * src_file,
const wchar_t * dest_file, VideoCodec codec, UINT32 bitrate = 4000000 ) :
m_OpenSrcFileSuccess(false ),
m_MP3Filename(mp3_file),
m_SrcFilename(src_file),
m_DestFilename(dest_file),
m_Width(0 ),
m_Height(0 ),
m_pImage(nullptr ),
m_cbWidth(4 * m_Width),
m_cbBuffer(m_cbWidth * m_Height),
m_pBuffer(nullptr ),
m_hThread(INVALID_HANDLE_VALUE),
m_evtRequest(INVALID_HANDLE_VALUE),
m_evtReply(INVALID_HANDLE_VALUE),
m_evtExit(INVALID_HANDLE_VALUE),
m_evtVideoEnded(INVALID_HANDLE_VALUE),
m_CoInited(false ),
m_MFInited(false ),
m_pSinkWriter(nullptr ),
m_VideoFPS(60 ),
m_FrameDuration(10 * 1000 * 1000 / m_VideoFPS),
m_VideoBitrate(bitrate),
m_EncCommonQuality(100 ),
m_VideoCodec(codec),
m_nStreams(0 )
{
Inside the constructor body, check_config_file is called to return width, height and fps.
int width = 0 ; int height = 0 ; int fps = 0 ;
if (check_config_file(m_SrcFilename.c_str(), &width, &height, &fps))
{
m_OpenSrcFileSuccess = true ;
m_Width = width;
m_Height = height;
m_cbWidth = 4 * m_Width;
m_cbBuffer = m_cbWidth * m_Height;
m_VideoFPS = fps;
m_FrameDuration = (10 * 1000 * 1000 / m_VideoFPS);
m_pImage = new (std::nothrow ) UINT32[m_Width * m_Height];
}
if (!m_OpenSrcFileSuccess)
return ;
if (!m_pImage)
return ;Next, CoInitializeEx is called to initialize the COM runtime before any Media Foundation function can be called. MFStartup() called to initialize the Media Foundation(MF) runtime. After that, we create m_pBuffer based on the dimension stored in m_cbBuffer. This is the classic case of premature optimization. The buffer is kept inside a member to avoid instantiating and allocating a memory buffer on every frame. It turns out that MFCreateMemoryBuffer does not destroy the buffer in every frame but return the buffer to a pool; whenever a buffer of the same dimension is requested, MF just gives you one of the buffers created previously.
HRESULT hr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
if (SUCCEEDED(hr))
{
m_CoInited = true ;
hr = MFStartup(MF_VERSION);
if (SUCCEEDED(hr))
{
m_MFInited = true ;
hr = MFCreateMemoryBuffer(m_cbBuffer, &m_pBuffer);
}
}
After IsValid() returns true, we create the Win32 event handle and OpenGL thread.
if (IsValid() == false )
{
return ;
}
if (SUCCEEDED(hr))
{
m_evtRequest = CreateEvent(NULL, FALSE, FALSE, NULL);
m_evtReply = CreateEvent(NULL, FALSE, FALSE, NULL);
m_evtExit = CreateEvent(NULL, FALSE, FALSE, NULL);
m_evtVideoEnded = CreateEvent(NULL, FALSE, FALSE, NULL);
m_hThread = CreateThread(NULL, 100000 , ThreadOpenGLProc, this , 0 , NULL);
}
}
Validity is determined by whether COM and MF runtime is initialized successfully.
const bool IsValid() const
{
return m_CoInited && m_MFInited;
}In the H264Writer destructor, m_evtExit is signalled and sleeps for 100 millisecond to ensure the OpenGL thread get the event. The all buffers and handles can be released safely. And MF and COM runtime are shut down.
~H264Writer()
{
SetEvent(m_evtExit);
Sleep(100 );
if (m_pImage)
{
delete [] m_pImage;
m_pImage = nullptr ;
}
m_pBuffer.Release();
if (m_evtRequest != INVALID_HANDLE_VALUE)
CloseHandle(m_evtRequest);
if (m_evtReply != INVALID_HANDLE_VALUE)
CloseHandle(m_evtReply);
if (m_evtExit != INVALID_HANDLE_VALUE)
CloseHandle(m_evtExit);
if (m_evtVideoEnded!=INVALID_HANDLE_VALUE)
CloseHandle(m_evtVideoEnded);
m_pSourceReader = nullptr ;
m_pSinkWriter = nullptr ;
if (m_MFInited)
MFShutdown();
if (m_CoInited)
CoUninitialize();
}
GetSourceDuration is used in H264Writer to get the duration of source MP3, through it can be used to duration of any media, including video. Duration is in 10 millionth of a second.
HRESULT GetSourceDuration(IMFMediaSource *pSource, MFTIME *pDuration)
{
*pDuration = 0 ;
IMFPresentationDescriptor *pPD = NULL;
HRESULT hr = pSource-> CreatePresentationDescriptor(&pPD);
if (SUCCEEDED(hr))
{
hr = pPD-> GetUINT64(MF_PD_DURATION, (UINT64*)pDuration);
pPD-> Release();
}
return hr;
}
Here is a short snippet on how to convert duration back to minutes and seconds familiar to humans.
MFTIME total_seconds = duration / 10000000 ;
MFTIME minute = total_seconds / 60 ;
MFTIME second = total_seconds % 60 ;
Next function is InitializeWriter().
HRESULT InitializeWriter(DWORD *videoStreamIndex, DWORD *audioStreamIndex)
{
HRESULT hr = S_OK;
m_pSourceReader = nullptr ;
m_pSinkWriter = nullptr ;
*videoStreamIndex = 1 ;
*audioStreamIndex = 0 ;
IMFMediaType *pMediaTypeOut = nullptr ;
IMFMediaType *pMediaTypeIn = nullptr ;
DWORD streamIndex=1 ;
CComPtr< IMFAttributes> pConfigAttrs;
We set the attributes that hardware accelerated transforms are preferred. When there are no hardware transforms installed on the system, software ones will be chosen.
do
{
hr = MFCreateAttributes(&pConfigAttrs, 1 );
BREAK_ON_FAIL(hr);
hr = pConfigAttrs-> SetUINT32(MF_READWRITE_ENABLE_HARDWARE_TRANSFORMS, TRUE);
BREAK_ON_FAIL(hr);
When the m_MP3Filename is specified, we create a m_pSourceReader that is able to decode mp3. pSource is used to get and print out the duration. which is useless. So you can delete the pSource line and all the lines below it.
if (m_MP3Filename.empty() == false )
{
hr = MFCreateSourceReaderFromURL(m_MP3Filename.c_str(),
pConfigAttrs, &m_pSourceReader);
BREAK_ON_FAIL(hr);
IMFMediaSource* pSource = nullptr ;
hr = m_pSourceReader-> GetServiceForStream(
MF_SOURCE_READER_MEDIASOURCE,
GUID_NULL, IID_IMFMediaSource,
(void **)&pSource
);
BREAK_ON_FAIL(hr);
MFTIME duration = 0 ;
hr = GetSourceDuration(pSource, &duration);
BREAK_ON_FAIL(hr);
if (pSource)
pSource-> Release();
printf(" Audio duration:%lld\n" , duration);
MFTIME total_seconds = duration / 10000000 ;
MFTIME minute = total_seconds / 60 ;
MFTIME second = total_seconds % 60 ;
printf(" Audio duration:%lld:%lld\n" , minute, second);
}
As you can see, our do-while is only executed once. The existence of do-while is mainly for BREAK_ON_FAIL macro to break out of it. Next, we create a SinkWriter. MapStreams(), SetVideoOutputType() and SetVideoInputType() will be explained shortly.
hr = MFCreateSinkWriterFromURL(m_DestFilename.c_str(),
nullptr , nullptr , &m_pSinkWriter);
BREAK_ON_FAIL(hr);
hr = MapStreams();
BREAK_ON_FAIL(hr);
hr = SetVideoOutputType(&pMediaTypeOut, streamIndex);
BREAK_ON_FAIL(hr);
hr = SetVideoInputType(&pMediaTypeIn, streamIndex);
BREAK_ON_FAIL(hr);
hr = m_pSinkWriter-> BeginWriting();
BREAK_ON_FAIL(hr);
*videoStreamIndex = streamIndex;
} while (false );
SafeRelease(&pMediaTypeOut);
SafeRelease(&pMediaTypeIn);
return hr;
}
BREAK_ON_FAIL and BREAK_ON_NULL macro is defined in such a way.
#define BREAK_ON_FAIL(value) if(FAILED(value)) break;
#define BREAK_ON_NULL(value, newHr) if(value == NULL) { hr = newHr; break; } SetVideoOutputType() is to set the parameters of video output. You can experiment with the values and see how it affects the output. As for what parameters to set, Google is your best friend. I set it to the highest quality.
HRESULT SetVideoOutputType(IMFMediaType** pMediaTypeOut, DWORD& streamIndex)
{
HRESULT hr = S_OK;
do
{
hr = MFCreateMediaType(pMediaTypeOut);
BREAK_ON_FAIL(hr);
hr = (*pMediaTypeOut)-> SetGUID(MF_MT_MAJOR_TYPE, MFMediaType_Video);
BREAK_ON_FAIL(hr);
if (m_VideoCodec==VideoCodec::HEVC)
{
hr = (*pMediaTypeOut)-> SetGUID(MF_MT_SUBTYPE, MFVideoFormat_HEVC);
BREAK_ON_FAIL(hr);
hr = (*pMediaTypeOut)-> SetUINT32(MF_MT_MPEG2_PROFILE,
eAVEncH265VProfile_Main_420_8);
BREAK_ON_FAIL(hr);
}
else
{
hr = (*pMediaTypeOut)-> SetGUID(MF_MT_SUBTYPE, MFVideoFormat_H264);
BREAK_ON_FAIL(hr);
hr = (*pMediaTypeOut)-> SetUINT32(MF_MT_MPEG2_PROFILE, eAVEncH264VProfile_High);
BREAK_ON_FAIL(hr);
}
BREAK_ON_FAIL(hr);
hr = (*pMediaTypeOut)-> SetUINT32(MF_MT_AVG_BITRATE, m_VideoBitrate);
BREAK_ON_FAIL(hr);
hr = (*pMediaTypeOut)-> SetUINT32
(MF_MT_INTERLACE_MODE, MFVideoInterlace_Progressive);
BREAK_ON_FAIL(hr);
hr = MFSetAttributeSize((*pMediaTypeOut), MF_MT_FRAME_SIZE, m_Width, m_Height);
BREAK_ON_FAIL(hr);
hr = MFSetAttributeRatio((*pMediaTypeOut), MF_MT_FRAME_RATE, m_VideoFPS, 1 );
BREAK_ON_FAIL(hr);
hr = MFSetAttributeRatio((*pMediaTypeOut), MF_MT_PIXEL_ASPECT_RATIO, 1 , 1 );
BREAK_ON_FAIL(hr);
hr = m_pSinkWriter-> AddStream((*pMediaTypeOut), &streamIndex);
} while (false );
return hr;
}
SetVideoInputType() is setting input video format which our OpenGL format is RGB32.
const GUID VIDEO_ENCODING_FORMAT = MFVideoFormat_H264;
const GUID VIDEO_INPUT_FORMAT = MFVideoFormat_RGB32;
HRESULT SetVideoInputType(IMFMediaType** pMediaTypeIn, DWORD& streamIndex)
{
HRESULT hr = S_OK;
do
{
hr = MFCreateMediaType(pMediaTypeIn);
BREAK_ON_FAIL(hr);
hr = (*pMediaTypeIn)-> SetGUID(MF_MT_MAJOR_TYPE, MFMediaType_Video);
BREAK_ON_FAIL(hr);
hr = (*pMediaTypeIn)-> SetGUID(MF_MT_SUBTYPE, VIDEO_INPUT_FORMAT);
BREAK_ON_FAIL(hr);
hr = (*pMediaTypeIn)-> SetUINT32
(MF_MT_INTERLACE_MODE, MFVideoInterlace_Progressive);
BREAK_ON_FAIL(hr);
hr = MFSetAttributeSize(*pMediaTypeIn, MF_MT_FRAME_SIZE, m_Width, m_Height);
BREAK_ON_FAIL(hr);
hr = MFSetAttributeRatio(*pMediaTypeIn, MF_MT_FRAME_RATE, m_VideoFPS, 1 );
BREAK_ON_FAIL(hr);
hr = MFSetAttributeRatio(*pMediaTypeIn, MF_MT_PIXEL_ASPECT_RATIO, 1 , 1 );
BREAK_ON_FAIL(hr);
hr = m_pSinkWriter-> SetInputMediaType(streamIndex, *pMediaTypeIn, NULL);
} while (false );
return hr;
}ConnectStream() is attempting to connect the input and output which the source and sink can agree on. This function is mainly boilerplate code.
HRESULT ConnectStream(DWORD dwStreamIndex,
const GUID& streamMajorType)
{
HRESULT hr = S_OK;
CComPtr< IMFMediaType> pPartialMediaType;
CComPtr< IMFMediaType> pFullMediaType;
BOOL fConfigured = FALSE;
GUID* intermediateFormats = NULL;
int nFormats = 0 ;
Here comes the familiar do-only-once do-while loop. We set the GUID of the container type.
do
{
hr = MFCreateMediaType(&pPartialMediaType);
BREAK_ON_FAIL(hr);
hr = pPartialMediaType-> SetGUID(MF_MT_MAJOR_TYPE, streamMajorType);
BREAK_ON_FAIL(hr);
if (streamMajorType == MFMediaType_Video)
{
intermediateFormats = intermediateVideoFormats;
nFormats = nIntermediateVideoFormats;
}
else if (streamMajorType == MFMediaType_Audio)
{
intermediateFormats = intermediateAudioFormats;
nFormats = nIntermediateAudioFormats;
}
else
{
hr = E_UNEXPECTED;
break ;
}
Next, we iterate over every format and find one that can match m_pSourceReader by SetCurrentMediaType(). When it is happy, we can GetCurrentMediaType to get the full media type. If none can match, we set hr to MF_E_INVALIDMEDIATYPE;.
for (int x = 0 ; x < nFormats; x++)
{
hr = pPartialMediaType-> SetGUID(MF_MT_SUBTYPE, intermediateFormats[x]);
BREAK_ON_FAIL(hr);
hr = m_pSourceReader-> SetCurrentMediaType(
dwStreamIndex, NULL, pPartialMediaType);
if (FAILED(hr))
{
hr = S_OK;
continue ;
}
pFullMediaType = NULL;
hr = m_pSourceReader-> GetCurrentMediaType(dwStreamIndex, &pFullMediaType);
hr = m_pSinkWriter-> SetInputMediaType(
dwStreamIndex, pFullMediaType, NULL);
if (FAILED(hr))
{
hr = S_OK;
continue ;
}
fConfigured = TRUE;
break ;
}
BREAK_ON_FAIL(hr);
if (!fConfigured)
{
hr = MF_E_INVALIDMEDIATYPE;
break ;
}
} while (false );
return hr;
}
MapStreams() is for MP3 file, so when it is not specified, we return. m_pSourceReader is for MP3 file. OpenGL source does not need a SourceReader because it is uncompressed and we know its format and there is no video file to read for OpenGL input, unless you can count the config.txt which contains dimension and FPS. MapStreams() is also mostly boilerplate code I copied somewhere.
HRESULT MapStreams(void )
{
if (m_MP3Filename.empty())
return S_OK;
HRESULT hr = S_OK;
BOOL isStreamSelected = FALSE;
DWORD sourceStreamIndex = 0 ;
DWORD sinkStreamIndex = 0 ;
GUID streamMajorType;
CComPtr< IMFMediaType> pStreamMediaType;
The code below add the audio stream to sinkwriter. A media file such as video can contain more than just video and audio, for example subtitle. For encoder, we do not care about media types other than MFMediaType_Audio. Ignore MFMediaType_Video in the code because MapStreams is called for MP3 m_pSourceReader.
do
{
m_nStreams = 0 ;
while (SUCCEEDED(hr))
{
hr = m_pSourceReader-> GetStreamSelection
(sourceStreamIndex, &isStreamSelected);
if (FAILED(hr))
{
hr = S_OK;
break ;
}
m_nStreams++;
hr = m_pSourceReader-> GetNativeMediaType(
sourceStreamIndex, 0 , &pStreamMediaType); BREAK_ON_FAIL(hr);
hr = pStreamMediaType-> GetMajorType(&streamMajorType);
BREAK_ON_FAIL(hr);
hr = m_pSourceReader-> SetStreamSelection(sourceStreamIndex, TRUE);
BREAK_ON_FAIL(hr);
if (streamMajorType == MFMediaType_Audio ||
streamMajorType == MFMediaType_Video)
{
hr = GetTranscodeMediaType(pStreamMediaType);
BREAK_ON_FAIL(hr);
hr = m_pSinkWriter-> AddStream(pStreamMediaType, &sinkStreamIndex);
BREAK_ON_FAIL(hr);
hr = ConnectStream(sourceStreamIndex, streamMajorType);
BREAK_ON_FAIL(hr);
}
else
{
hr = m_pSinkWriter-> AddStream(pStreamMediaType, &sinkStreamIndex);
BREAK_ON_FAIL(hr);
}
if (sourceStreamIndex != sinkStreamIndex)
{
hr = E_UNEXPECTED;
break ;
}
sourceStreamIndex++;
pStreamMediaType = NULL;
}
BREAK_ON_FAIL(hr);
} while (false );
return hr;
}GetTranscodeAudioType() is to set output audio type. I have forgotten why destination format is MFAudioFormat_AAC, you are welcome to set to MFAudioFormat_MP3.
HRESULT GetTranscodeAudioType(
CComPtr< IMFMediaType> & pStreamMediaType)
{
HRESULT hr = S_OK;
do
{
BREAK_ON_NULL(pStreamMediaType, E_POINTER);
hr = pStreamMediaType-> DeleteAllItems();
BREAK_ON_FAIL(hr);
pStreamMediaType-> SetGUID(MF_MT_MAJOR_TYPE, MFMediaType_Audio);
BREAK_ON_FAIL(hr);
hr = pStreamMediaType-> SetGUID(MF_MT_SUBTYPE, MFAudioFormat_AAC);
BREAK_ON_FAIL(hr);
hr = pStreamMediaType-> SetUINT32(MF_MT_AUDIO_BITS_PER_SAMPLE, 16 );
BREAK_ON_FAIL(hr);
hr = pStreamMediaType-> SetUINT32(MF_MT_AUDIO_SAMPLES_PER_SECOND, 44100 );
BREAK_ON_FAIL(hr);
hr = pStreamMediaType-> SetUINT32(MF_MT_AUDIO_NUM_CHANNELS, 2 );
BREAK_ON_FAIL(hr);
hr = pStreamMediaType-> SetUINT32(MF_MT_AUDIO_AVG_BYTES_PER_SECOND, 16000 );
BREAK_ON_FAIL(hr);
hr = pStreamMediaType-> SetUINT32(MF_MT_AUDIO_BLOCK_ALIGNMENT, 1 );
BREAK_ON_FAIL(hr);
} while (false );
return hr;
}
Similarly, GetTranscodeVideoType() is to set output video type.
HRESULT GetTranscodeVideoType(
CComPtr< IMFMediaType> & pStreamMediaType)
{
HRESULT hr = S_OK;
do
{
BREAK_ON_NULL(pStreamMediaType, E_POINTER);
hr = pStreamMediaType-> DeleteAllItems();
BREAK_ON_FAIL(hr);
pStreamMediaType-> SetGUID(MF_MT_MAJOR_TYPE, MFMediaType_Video);
BREAK_ON_FAIL(hr);
if (m_VideoCodec == VideoCodec::H264)
{
hr = pStreamMediaType-> SetGUID(MF_MT_SUBTYPE, MFVideoFormat_H264);
}
else
{
hr = pStreamMediaType-> SetGUID(MF_MT_SUBTYPE, MFVideoFormat_HEVC);
}
BREAK_ON_FAIL(hr);
hr = MFSetAttributeSize(
pStreamMediaType, MF_MT_FRAME_SIZE, m_Width, m_Height); BREAK_ON_FAIL(hr);
hr = MFSetAttributeRatio(
pStreamMediaType, MF_MT_FRAME_RATE, m_VideoFPS, 1 ); BREAK_ON_FAIL(hr);
hr = pStreamMediaType-> SetUINT32(MF_MT_AVG_BITRATE, m_VideoBitrate);
BREAK_ON_FAIL(hr);
hr = pStreamMediaType-> SetUINT32(MF_MT_INTERLACE_MODE,
MFVideoInterlace_Progressive);
BREAK_ON_FAIL(hr);
hr = MFSetAttributeSize(pStreamMediaType, MF_MT_PIXEL_ASPECT_RATIO, 1 , 1 );
BREAK_ON_FAIL(hr);
} while (false );
return hr;
}
GetTranscodeMediaType() calls either GetTranscodeAudioType() or GetTranscodeVideoType() to do its work.
HRESULT GetTranscodeMediaType(
CComPtr< IMFMediaType> & pStreamMediaType)
{
HRESULT hr = S_OK;
GUID streamMajorType;
do
{
hr = pStreamMediaType-> GetMajorType(&streamMajorType);
BREAK_ON_FAIL(hr);
if (streamMajorType == MFMediaType_Audio)
{
hr = GetTranscodeAudioType(pStreamMediaType);
}
else if (streamMajorType == MFMediaType_Video)
{
hr = GetTranscodeVideoType(pStreamMediaType);
}
} while (false );
return hr;
}
WriteVideoFrame() copies m_pImage to pData. And sets buffer length. Then it creates a sample to attach m_pBuffer. Of course, sample must be set with its sampling time and duration. Finally, send the sample to the SinkWriter.
HRESULT WriteVideoFrame(
DWORD streamIndex,
const LONGLONG& rtStart
)
{
IMFSample *pSample = NULL;
BYTE *pData = NULL;
HRESULT hr = m_pBuffer-> Lock(&pData, NULL, NULL);
if (SUCCEEDED(hr))
{
hr = MFCopyImage(
pData, m_cbWidth, (BYTE*)m_pImage, m_cbWidth, m_cbWidth, m_Height );
}
if (m_pBuffer)
{
m_pBuffer-> Unlock();
}
if (SUCCEEDED(hr))
{
hr = m_pBuffer-> SetCurrentLength(m_cbBuffer);
}
if (SUCCEEDED(hr))
{
hr = MFCreateSample(&pSample);
}
if (SUCCEEDED(hr))
{
hr = pSample-> AddBuffer(m_pBuffer);
}
if (SUCCEEDED(hr))
{
hr = pSample-> SetSampleTime(rtStart);
}
if (SUCCEEDED(hr))
{
hr = pSample-> SetSampleDuration(m_FrameDuration);
}
if (SUCCEEDED(hr))
{
hr = m_pSinkWriter-> WriteSample(streamIndex, pSample);
}
SafeRelease(&pSample);
return hr;
}
WriteAudioFrame() reads sample from m_pSourceReader and sends it to SinkWriter.
HRESULT WriteAudioFrame(DWORD streamIndex, LONGLONG& timestamp)
{
HRESULT hr = S_OK;
DWORD flags = 0 ;
CComPtr< IMFSample> pSample;
do
{
hr = m_pSourceReader-> ReadSample(
(DWORD)MF_SOURCE_READER_ANY_STREAM, 0 , &streamIndex, &flags, ×tamp, &pSample); BREAK_ON_FAIL(hr);
if (pSample != NULL)
{
hr = m_pSinkWriter-> WriteSample(streamIndex, pSample);
BREAK_ON_FAIL(hr);
}
else if (flags & MF_SOURCE_READERF_STREAMTICK)
{
hr = m_pSinkWriter-> SendStreamTick(streamIndex, timestamp);
BREAK_ON_FAIL(hr);
}
if (flags & MF_SOURCE_READERF_ENDOFSTREAM)
{
hr = m_pSinkWriter-> NotifyEndOfSegment(streamIndex);
BREAK_ON_FAIL(hr);
}
pSample = NULL;
} while (false );
return hr;
}
Process() is a long running function which calls InitializeWriter and then enters into an infinite loop. At the start of loop, it signals m_evtRequest for frame and then waits for OpenGL thread to reply with m_evtVideoEnded or m_evtReply. If it is m_evtReply that is signalled, then WriteVideoFrame and/or WriteAudioFrame are called to send sample to SinkWriter. At the end, Finalize() is called to finalize video file.
const bool Process()
{
if (IsValid())
{
DWORD video_stream = 0 ;
DWORD audio_stream = 0 ;
HRESULT hr = InitializeWriter(&video_stream, &audio_stream);
if (SUCCEEDED(hr))
{
LONGLONG rtStart = 0 ;
bool success = true ;
HRESULT hr = S_OK;
bool audio_done = false ;
DWORD audio_stream = 0 ;
LONGLONG audio_timestamp = 0 ;
while (true )
{
SetEvent(m_evtRequest);
success = true ;
HANDLE arr[2 ];
arr[0 ] = m_evtVideoEnded;
arr[1 ] = m_evtReply;
DWORD dw = WaitForMultipleObjects(2 , arr, FALSE, INFINITE);
if (WAIT_OBJECT_0 == dw)
{
OutputDebugStringA(" VideoEnded" );
break ;
}
if (WAIT_OBJECT_0 + 1 != dw)
{
OutputDebugStringA(" E_FAIL" );
success = false ;
break ;
}
if (success)
{
hr = WriteVideoFrame(video_stream, rtStart);
if (FAILED(hr))
{
success = false ;
break ;
}
rtStart += m_FrameDuration;
if (m_MP3Filename.empty() == false )
{
if (rtStart < audio_timestamp)
continue ;
if (!audio_done)
{
hr = WriteAudioFrame(audio_stream, audio_timestamp);
if (FAILED(hr))
{
audio_done = true ;
}
}
}
}
}
if (success)
{
hr = m_pSinkWriter-> Finalize();
}
m_pSinkWriter.Release();
return success;
}
}
return false ;
}This section focuses mainly on asm.js aspect of OpenGL framework that comes bundled with the demo. If you are only interested in the video encoder, you can safely ignore this section. If you want to run your app on the web browser with the framework, this is the section for you. The design choice of framework is based on lowest technologies mainstream WebGL and web browser environment can work with. Since WebGL is a safe subset based on OpenGL 2.0 ES in such a way that WebGL calls can be translated to OpenGL 2.0 calls with little effort. Without coincidence, this is also the maximum OpenGL version the framework can support.
Change Your URL
Change your IP address/domain/port accordingly in SRC_FOLDER in the Program.cpp . SRC_FOLDER is used to download your assets from. Switch to http if you are not using https.
#ifdef __EMSCRIPTEN__
#define SRC_FOLDER "https://localhost:44319/"
#else
#define SRC_FOLDER ".\\"
#endif Recompile the Code as asm.js
Recompile the code for new URL to take effect, if you are on Windows 10 and are comfortable tinkering with Bash commands, enable Windows Subsystem for Linux and install Ubuntu from MS Store and install Emscripten . Run GNU make.
In the Makefile, change to -s WASM=0
make all
Recompile the Code as Webassembly
Remove or change to -s WASM=1 because default option is compiling to Webassembly when WASM is not specified. The reason I did not do so, because IIS do not recognise the wasm mime type added to it.
No Assimp Support
Assimp is not supported simply because there is no Emscripten port for Assimp. Instead, Tiny OBJ Loader is used to load simple 3D model in Wavefront OBJ format. OBJ file extensions ends in *.obj and *.mtl and I have modified the library to load in *.obj.txt and *.mtl.txt because I want to avoid adding new mime types in the web server.
Downloading Your Assets
For drawing anything on screen, derive your class from DrawableSceneComponent and **must** call DownloadFiles() in the constructor to download your assets from relative subfolders because asm.js must have all assets downloaded before the main rendering loop is run. DownloadFiles calls OpenFile on the files directly on a desktop app. If the code is compiled with EMSCRIPTEN macro defined, it will first download files and then open.
No Downloading of Shader
The shader code is inline with C++11 raw string literals to save downloading effort.
Hardware acceleration is available now in the library.
int numWorkerThreads: 0 leaves to defaultint qualityVsSpeed: [0:100] 0 for speed, 100 for qualityRateControlMode mode: 3 modes to choose from UnconstrainedVBR, Quality, CBR (VBR is variable bitrate and CBR is constant bitrate)int quality: Only valid when mode is Quality. [0:100] 0 for smaller file size and lower quality, 100 for bigger file size and higher quality
27th October, 2022 : Added Mandy Frenzy video and links in the introduction25th March, 2022 : Added HasH264() and HasHEVC() to check for presence of hardware accelerated or software encoder on the system. Remember to call CoInitialize() before calling HasH264() and HasHEVC(). Put back option of software encoding for testing in VMs.Note : Quality settings are ignored when software encoding is selected because they do not work.26th July, 2020 : Added 1.0.4 version to adjust quality and encoding speed parameters (See quality section for more information)25th July, 2020 : Added 1.0.3 version for hardware acceleration (See hardware acceleration section for more information)25th October, 2019 : Updated the OpenGL framework to be compatible with latest Emscripten. Fixed incorrect screen width and height.18th December, 2018 : First release
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