# WebM file output

Video Capture SDK .Net Video Edit SDK .Net Media Blocks SDK .Net

WebM is an open, royalty-free media file format designed for the web. It provides high-quality video streaming with low computational overhead. WebM is optimized for HTML5 video and supports VP8/VP9 video codecs along with Vorbis and Opus audio codecs.

# Windows-only output

VideoCaptureCore VideoEditCore

The Windows-specific implementation uses the WebMOutput class from the VisioForge.Core.Types.Output namespace.

# Basic Usage 

using VisioForge.Core.Types.Output;

// Create WebM output settings
var webmOutput = new WebMOutput();

// Configure basic settings
webmOutput.Video_Mode = VP8QualityMode.Realtime;
webmOutput.Video_EndUsage = VP8EndUsageMode.VBR;
webmOutput.Video_Encoder = WebMVideoEncoder.VP8;
webmOutput.Video_Bitrate = 2000;
webmOutput.Audio_Quality = 80;

// Apply settings to your core object
var core = new VideoCaptureCore(); // or VideoEditCore
core.Output_Format = webmOutput;
core.Output_Filename = "output.webm";

# Advanced Configuration Options

# Video Settings 

var webmOutput = new WebMOutput();

// Thread Management
webmOutput.Video_ThreadCount = 4; // Number of encoding threads

// Quality Control
webmOutput.Video_MinQuantizer = 4;  // Range: 0-63 (lower is better quality)
webmOutput.Video_MaxQuantizer = 48; // Range: 0-63
webmOutput.Video_Bitrate = 2000;    // Target bitrate in kbps

// Keyframe Control
webmOutput.Video_Keyframe_MinInterval = 30;  // Minimum frames between keyframes
webmOutput.Video_Keyframe_MaxInterval = 300; // Maximum frames between keyframes
webmOutput.Video_Keyframe_Mode = VP8KeyframeMode.Auto;

// Performance Optimization
webmOutput.Video_CPUUsed = 0;           // Range: -16 to 16
webmOutput.Video_LagInFrames = 25;      // Frame look-ahead buffer
webmOutput.Video_ErrorResilient = true; // Error resilience for streaming

# Error Resilience and Buffer Control 

// Buffer Management
webmOutput.Video_Decoder_Buffer_Size = 6000;        // Buffer size in ms
webmOutput.Video_Decoder_Buffer_InitialSize = 4000; // Initial buffer in ms
webmOutput.Video_Decoder_Buffer_OptimalSize = 5000; // Optimal buffer in ms

// Rate Control
webmOutput.Video_UndershootPct = 50;  // Undershoot percentage
webmOutput.Video_OvershootPct = 50;   // Overshoot percentage

# Cross-platform WebM output

VideoCaptureCoreX VideoEditCoreX MediaBlocksPipeline

The cross-platform implementation uses the WebMOutput class from the VisioForge.Core.Types.X.Output namespace, which provides more flexibility in codec selection.

# Basic Usage 

using VisioForge.Core.Types.X.Output;
using VisioForge.Core.Types.X.VideoEncoders;
using VisioForge.Core.Types.X.AudioEncoders;

// Create WebM output with filename
var webmOutput = new WebMOutput("output.webm");

// Configure VP8 video encoder
webmOutput.Video = new VP8EncoderSettings(); 

// Configure Vorbis audio encoder
webmOutput.Audio = new VorbisEncoderSettings();

Add the WebM output to the Video Capture SDK core instance:

var core = new VideoCaptureCoreX();
core.Outputs_Add(webmOutput, true);

Set the output format for the Video Edit SDK core instance:

var core = new VideoEditCoreX();
core.Output_Format = webmOutput;

Create a Media Blocks WebM output instance:

var vorbis = new VorbisEncoderSettings();
var vp9 = new VP9EncoderSettings();
var webmSettings = new WebMSinkSettings("output.webm");
var webmOutput = new WebMOutputBlock(webmSettings, vp9, vorbis);

Check out the video and audio encoders that you can use:

# Best Practices

  1. Encoder Selection:

    • Use VP8 for broader compatibility and faster encoding
    • Use VP9 for better compression efficiency and quality
    • Choose Opus over Vorbis for better audio quality at lower bitrates

  2. Performance Optimization:

    • Set thread count based on available CPU cores
    • Use appropriate keyframe intervals (shorter for streaming, longer for storage)
    • Balance quality vs. performance using CPU usage settings

  3. Quality Control:

    • Use VBR (Variable Bit Rate) for better quality consistency
    • Set appropriate buffer sizes for streaming scenarios
    • Enable error resilience for streaming applications

# Dependencies

Make sure to include the necessary NuGet packages:

Visit our GitHub page to get more code samples.