Snapshot

The simplest way to get snapshot is by FFmpeg.Conversions.FromSnippet.Snapshot:

string output = Path.Combine(Path.GetTempPath(), Guid.NewGuid() + ".png");

IConversion conversion = await FFmpeg.Conversions.FromSnippet.Snapshot(Resources.Mp4WithAudio, output, TimeSpan.FromSeconds(0));
IConversionResult result = await conversion.Start();

Conversion returns snapshot in format specified in output path so outputPath should be with correct extension. Image has exactly the same size as a video.