# IFFmpegSourceSettings Interface Reference

The IFFmpegSourceSettings interface provides advanced configuration options for the FFMPEG Source DirectShow filter. This interface enables developers to control hardware acceleration, buffering behavior, custom FFmpeg options, and various callbacks for media playback.

• Interface Name: IFFmpegSourceSettings
• GUID: {1974D893-83E4-4F89-9908-795C524CC17E}
• Inherits From: IUnknown

Complete interface definitions are available on GitHub:

• C# (.NET): IFFmpegSourceSettings.cs
• C++ Header: IFFmpegSourceSettings.h
• Delphi: VCFiltersAPI.pas (search for IFFMPEGSourceSettings)

All interface definitions include:

• Complete method signatures with proper marshalling attributes
• Callback delegate definitions
• Enumeration types (buffering modes, media types)
• Usage documentation and examples

Retrieves the current hardware acceleration state.

Syntax (C++):

BOOL GetHWAccelerationEnabled();

Syntax (C#):

[PreserveSig]
bool GetHWAccelerationEnabled();

Returns: TRUE if hardware acceleration is enabled, FALSE otherwise.

Default: TRUE

Enables or disables hardware video decoding acceleration.

Syntax (C++):

HRESULT SetHWAccelerationEnabled(BOOL enabled);

Syntax (C#):

[PreserveSig]
int SetHWAccelerationEnabled([MarshalAs(UnmanagedType.Bool)] bool enabled);

Parameters:

• enabled: Set to TRUE to enable hardware acceleration, FALSE to disable.

Returns: S_OK (0) on success, error code otherwise.

Usage Notes:

• Must be called before connecting downstream video filters
• When enabled, the filter attempts to use hardware decoding (DXVA, NVDEC, QuickSync, etc.)
• Falls back to software decoding if hardware acceleration is unavailable
• Hardware acceleration significantly improves performance for H.264, H.265, VP9, and AV1 codecs

Example (C++):

IFFmpegSourceSettings* pSettings = nullptr;
pFilter->QueryInterface(IID_IFFmpegSourceSettings, (void**)&pSettings);

// Enable hardware acceleration
pSettings->SetHWAccelerationEnabled(TRUE);

pSettings->Release();

Example (C#):

var settings = filter as IFFmpegSourceSettings;
if (settings != null)
{
    // Enable hardware acceleration
    settings.SetHWAccelerationEnabled(true);
}

Retrieves the current source loading timeout value.

Syntax (C++):

DWORD GetLoadTimeOut();

Syntax (C#):

[PreserveSig]
uint GetLoadTimeOut();

Returns: Timeout value in milliseconds.

Default: 15000 (15 seconds)

Sets the timeout duration for source loading operations.

Syntax (C++):

HRESULT SetLoadTimeOut(DWORD milliseconds);

Syntax (C#):

[PreserveSig]
int SetLoadTimeOut(uint milliseconds);

Parameters:

• milliseconds: Timeout duration in milliseconds.

Returns: S_OK (0) on success.

Usage Notes:

• Must be called before loading the source file/URL
• Particularly important for network streams that may have slow connection times
• Set higher values for slow network connections or large files
• Set lower values to fail fast on unreachable sources

Example (C++):

// Set 30-second timeout for network streams
pSettings->SetLoadTimeOut(30000);

// Load RTSP stream
IFileSourceFilter* pFileSource = nullptr;
pFilter->QueryInterface(IID_IFileSourceFilter, (void**)&pFileSource);
pFileSource->Load(L"rtsp://example.com/stream", nullptr);

Retrieves the current buffering mode.

Syntax (C++):

FFMPEG_SOURCE_BUFFERING_MODE GetBufferingMode();

Syntax (C#):

[PreserveSig]
FFMPEG_SOURCE_BUFFERING_MODE GetBufferingMode();

Returns: Current buffering mode (see enumeration below).

Default: FFMPEG_SOURCE_BUFFERING_MODE_AUTO

Sets the buffering mode for live sources.

Syntax (C++):

HRESULT SetBufferingMode(FFMPEG_SOURCE_BUFFERING_MODE mode);

Syntax (C#):

[PreserveSig]
int SetBufferingMode(FFMPEG_SOURCE_BUFFERING_MODE mode);

Parameters:

• mode: Buffering mode to use.

Returns: S_OK (0) on success.

Usage Notes:

• Must be called before loading the source
• Affects latency and stability for live streams

Buffering Modes:

Example (C++):

// Disable buffering for low-latency RTSP stream
pSettings->SetBufferingMode(FFMPEG_SOURCE_BUFFERING_MODE_OFF);
pSettings->SetLoadTimeOut(5000); // 5-second timeout

Example (C#):

// Enable buffering for unstable network
settings.SetBufferingMode(FFMPEG_SOURCE_BUFFERING_MODE.ON);

Sets a custom FFmpeg option for the demuxer or decoder.

Syntax (C++):

HRESULT SetCustomOption(LPSTR name, LPSTR value);

Syntax (C#):

[PreserveSig]
int SetCustomOption([MarshalAs(UnmanagedType.LPStr)] string name,
                     [MarshalAs(UnmanagedType.LPStr)] string value);

Parameters:

• name: Option name (ASCII string).
• value: Option value (ASCII string).

Returns: S_OK (0) on success.

Usage Notes:

• Must be called before loading the source
• Allows passing any FFmpeg AVFormatContext or AVCodecContext option
• Options are passed directly to FFmpeg libraries
• Invalid options are ignored with a warning

Common Options:

Example (C++):

// Configure RTSP to use TCP transport
pSettings->SetCustomOption("rtsp_transport", "tcp");

// Set network timeout to 5 seconds
pSettings->SetCustomOption("timeout", "5000000"); // 5 seconds in microseconds

// Increase probe size for better format detection
pSettings->SetCustomOption("probesize", "10000000"); // 10MB

Example (C#):

// Low-latency configuration
settings.SetCustomOption("fflags", "nobuffer");
settings.SetCustomOption("flags", "low_delay");
settings.SetCustomOption("probesize", "32");

Clears all previously set custom options.

Syntax (C++):

HRESULT ClearCustomOptions();

Syntax (C#):

[PreserveSig]
int ClearCustomOptions();

Returns: S_OK (0) on success.

Usage Notes:

• Must be called before loading the source
• Resets all custom options to FFmpeg defaults

Example (C++):

pSettings->ClearCustomOptions();

Sets a callback function to receive decoded video/audio data.

Syntax (C++):

HRESULT SetDataCallback(FFMPEGDataCallbackDelegate callback);

Syntax (C#):

[PreserveSig]
int SetDataCallback([MarshalAs(UnmanagedType.FunctionPtr)] FFMPEGDataCallbackDelegate callback);

Parameters:

• callback: Pointer to callback function.

Returns: S_OK (0) on success.

Callback Signature (C++):

typedef HRESULT(_stdcall* FFMPEGDataCallbackDelegate) (
    BYTE* buffer,        // Pointer to data buffer
    int bufferLen,       // Buffer length in bytes
    int dataType,        // 0 = video, 1 = audio
    LONGLONG startTime,  // Start timestamp (100-nanosecond units)
    LONGLONG stopTime    // Stop timestamp (100-nanosecond units)
);

Usage Notes:

• Callback is invoked for each decoded frame/audio sample
• Called from filter's streaming thread - keep processing minimal
• Buffer data is valid only during callback execution
• Return S_OK from callback to continue processing

Example (C++):

HRESULT __stdcall DataCallback(BYTE* buffer, int bufferLen, int dataType,
                                LONGLONG startTime, LONGLONG stopTime)
{
    if (dataType == 0) // Video
    {
        // Process video frame
        ProcessVideoFrame(buffer, bufferLen, startTime);
    }
    else // Audio
    {
        // Process audio data
        ProcessAudioData(buffer, bufferLen);
    }
    return S_OK;
}

// Set callback
pSettings->SetDataCallback(&DataCallback);

Sets a callback function to receive timestamp information.

Syntax (C++):

HRESULT SetTimestampCallback(FFMPEGTimestampCallbackDelegate callback);

Syntax (C#):

[PreserveSig]
int SetTimestampCallback([MarshalAs(UnmanagedType.FunctionPtr)] FFMPEGTimestampCallbackDelegate callback);

Parameters:

• callback: Pointer to callback function.

Returns: S_OK (0) on success.

Callback Signature (C++):

typedef HRESULT(_stdcall* FFMPEGTimestampCallbackDelegate) (
    int mediaType,              // 0 = video, 1 = audio
    __int64 demuxerStartTime,   // Demuxer start time
    __int64 streamStartTime,    // Stream start time
    __int64 timestamp           // Current timestamp
);

Usage Notes:

• Useful for timestamp analysis and synchronization debugging
• Called for each decoded frame/sample

Enables or disables audio stream processing.

Syntax (C++):

HRESULT SetAudioEnabled(BOOL enabled);

Syntax (C#):

[PreserveSig]
int SetAudioEnabled([MarshalAs(UnmanagedType.Bool)] bool enabled);

Parameters:

• enabled: Set to TRUE to enable audio, FALSE to disable.

Returns: S_OK (0) on success.

Usage Notes:

• Must be called before loading the source
• When disabled, audio streams are not decoded (saves CPU/memory)
• Useful for video-only applications

Example (C++):

// Disable audio for video-only processing
pSettings->SetAudioEnabled(FALSE);

• IFileSourceFilter - Standard DirectShow interface for loading files/URLs
• IAMStreamSelect - Select between multiple audio/video streams
• IMediaSeeking - Seek to specific positions in the media
• IAMStreamConfig - Configure video/audio format

• FFMPEG Source Filter Overview - Product overview and features
• Code Examples - Complete working code samples

• C# Interface (.NET) - Complete .NET interface definition
• C++ Interface Header - C++ header file
• Delphi Interface - Delphi interface definition

• GitHub Samples Repository - Complete working examples for all platforms

• FFmpeg Documentation - FFmpeg library documentation
• DirectShow SDK - Microsoft DirectShow documentation