FromSecond and ToSecond options on ExtractFrames

[PhilipQuirke]

The ExtractFrames function pulls all frames for a video. For long videos this is slow. Also for my application the ability to pull selected portions of the video is necessary.

FFMPeg supports efficient from/to second selection

I'd like the existing function ExtractFrames to support optional FromSecond / ToSecond parameters

[PhilipQuirke]

The existing code can be updated as follows (assuming new int _videoSettings.FromSecond and _videoSettings.ToSecond params):

    /// <summary>
    /// Execute command to extract all/some frames from video
    /// </summary>
    private void ExtractFrames()
    {
        var (w, h) = (_videoSettings.Width, _videoSettings.Height);

        var vfOptions = string.Empty;

        // Check if the time range is specified
        if ((_videoSettings.FromSecond > 0) && (_videoSettings.ToSecond > 0))
        {
            // Add the (optional) time selection range using -ss (seek) and -t (duration)
            var duration = Math.Max( 1, _videoSettings.ToSecond - _videoSettings.FromSecond + 1 ); // Minimum duration is 1 second
            vfOptions = $"-ss {_videoSettings.FromSecond.ToString(CultureInfo.InvariantCulture)} -t {duration.ToString(CultureInfo.InvariantCulture)}";
        }

        vfOptions += $" -vf fps={FormatedFps},scale={w}:{h}";

        Execute($@"-i ""{_videoSettings.VideoFile}"" -vsync vfr {vfOptions} ""{Path.Combine(_videoSettings.TempFolder, $"%d.{FRAME_FORMAT}")}""");
    }