Loxifi.FFmpeg 1.0.9

Loxifi.FFmpeg

Cross-platform .NET 8.0 FFmpeg P/Invoke library for media transcoding. Targets Windows (x64), Linux (x64), and Android (arm64).

Ships in two license variants:

• LGPL — safe for proprietary/closed-source apps (dynamic linking)
• GPL — adds libx264, libx265, libxvid (requires your app to be GPL if distributed)

Usage

Mux audio and video together (fixing DASH files)

When you have separate video-only and audio-only files (e.g. from DASH streams), combine them into a single file. This is a stream copy operation — no re-encoding, so it's fast.

using Loxifi.FFmpeg.Transcoding;

// Combine separate video and audio files into one MP4
MediaOperations.Mux("video_only.mp4", "audio_only.mp4", "output.mp4");

// Async version
await MediaOperations.MuxAsync("video_only.mp4", "audio_only.mp4", "output.mp4");

// In-memory using streams (no disk I/O — ideal for DASH on Android/mobile)
using var videoStream = GetVideoStream();   // any System.IO.Stream
using var audioStream = GetAudioStream();
using var output = new MemoryStream();
MediaOperations.Mux(videoStream, audioStream, output);

Resize video to target file size (Discord upload limit)

Re-encodes the video to fit within a target file size in bytes. Audio is stream-copied (not re-encoded). The video bitrate is calculated automatically from the target size and duration.

using Loxifi.FFmpeg.Transcoding;

// Resize to fit within 25MB (Discord Nitro limit)
long targetSize = 25 * 1024 * 1024; // 25MB in bytes
MediaOperations.ResizeToFileSize("input.mp4", "output.mp4", targetSize);

// With progress reporting
var progress = new Progress<TranscodeProgress>(p =>
    Console.WriteLine($"{p.Percent:F1}% ({p.Position}/{p.Duration})"));

await MediaOperations.ResizeToFileSizeAsync("input.mp4", "output.mp4", targetSize, progress);

// Stream-based (no disk I/O)
using var input = File.OpenRead("input.mp4");
using var output = new MemoryStream();
MediaOperations.ResizeToFileSize(input, output, targetSize);

Convert GIF to MP4

Converts an animated GIF to an MP4 video. MP4 is dramatically smaller and plays better everywhere.

using Loxifi.FFmpeg.Transcoding;

MediaOperations.GifToMp4("funny.gif", "funny.mp4");

// Stream-based
using var gif = File.OpenRead("funny.gif");
using var mp4 = File.Create("funny.mp4");
MediaOperations.GifToMp4(gif, mp4);

Codec selection (no magic strings)

All codecs and container formats are strongly typed. Use LGPL.Video.* / LGPL.Audio.* for LGPL builds, or GPL.Video.* / GPL.Audio.* for GPL builds:

using Loxifi.FFmpeg.Transcoding;
using Loxifi.FFmpeg.Transcoding.Codecs;

// LGPL build — available codecs are discoverable via intellisense
using var transcoder = new MediaTranscoder();
transcoder.Transcode(new TranscodeOptions
{
    InputPath = "input.mkv",
    OutputPath = "output.webm",
    OutputFormat = ContainerFormat.WebM,
    VideoCodec = LGPL.Video.Vp9,
    AudioCodec = LGPL.Audio.Opus,
});

// GPL build — includes all LGPL codecs plus GPL-only ones
transcoder.Transcode(new TranscodeOptions
{
    InputPath = "input.mkv",
    OutputPath = "output.mp4",
    OutputFormat = ContainerFormat.Mp4,
    VideoCodec = GPL.Video.X264,      // H.264 (GPL only)
    AudioCodec = GPL.Audio.Aac,
});

// Stream-based transcoding (no disk I/O)
transcoder.Transcode(new StreamTranscodeOptions
{
    InputStream = inputStream,
    OutputStream = outputStream,
    OutputFormat = ContainerFormat.Mp4,
    VideoCodec = LGPL.Video.Mpeg4,
});

Low-level: Stream copy (remux without re-encoding)

using Loxifi.FFmpeg.Transcoding;

using var transcoder = new MediaTranscoder();
transcoder.Transcode(new TranscodeOptions
{
    InputPath = "input.mkv",
    OutputPath = "output.mp4",
    // VideoCodec = null (default) means stream copy
    // AudioCodec = null (default) means stream copy
});

Low-level: Probe file metadata

using Loxifi.FFmpeg.Transcoding;

MediaInfo info = MediaInfo.Probe("video.mp4");
Console.WriteLine($"Duration: {info.Duration}");
Console.WriteLine($"Video: {info.VideoStream?.Width}x{info.VideoStream?.Height}");
Console.WriteLine($"Audio: {info.AudioStream?.SampleRate}Hz, {info.AudioStream?.Channels}ch");

NuGet Packages

All runtime packages include the same 14 codec libraries (17 for GPL). See below for the full list.

Bundled Codecs

All platforms are built from source with identical configuration for full parity.

Additional utility libraries: libdav1d (AV1 decoder), libopencore-amr (AMR voice), libopenjpeg (JPEG 2000), libzimg (image scaling).

License

The core Loxifi.FFmpeg library is MIT-licensed. The native FFmpeg binaries are available in two license variants:

• LGPL v3 — Loxifi.FFmpeg.Runtime.{platform} packages. Safe for proprietary apps using dynamic linking.
• GPL v3 — Loxifi.FFmpeg.Runtime.{platform}.GPL packages. Adds libx264/libx265/libxvid. Requires your distributed app to be GPL-licensed.

Choose the runtime package that matches your licensing requirements.