private void MarkLastFrameAsInvalid()
{
if (LastFrame != null)
LastFrame.Invalid = true;
LastFrame = null;
}
/// <summary>
/// Retrieves a video frame at a timestamp
/// </summary>
/// <remarks>
/// <para>In FFMS2, the equivalent is <c>FFMS_GetFrameByTime</c>.</para>
/// <para>The returned frame is owned by the given <see cref="VideoSource">VideoSource object</see>, and remains valid until the video source is destroyed, a different frame is requested from the video source, or the video source's input or output format is changed.</para>
/// <para>Does the exact same thing as <see cref="GetFrame(int)">GetFrame</see> except instead of giving it a frame number you give it a timestamp in seconds, and it will retrieve the frame that starts closest to that timestamp.</para>
/// <para>This function exists for the people who are too lazy to build and traverse a mapping between frame numbers and timestamps themselves.</para>
/// </remarks>
/// <param name="time">Timestamp</param>
/// <returns>The generated <see cref="Frame">Frame object</see>.</returns>
/// <seealso cref="GetFrame(int)"/>
/// <exception cref="ArgumentOutOfRangeException">Trying to access a Frame that doesn't exist.</exception>
public Frame GetFrame(double time)
{
if (time < 0 || time > LastTime)
throw new ArgumentOutOfRangeException(@"time", "That frame doesn't exist.");
var err = new FFMS_ErrorInfo
{
BufferSize = 1024,
Buffer = new String((char) 0, 1024)
};
MarkLastFrameAsInvalid();
IntPtr framePtr;
lock (this)
{
framePtr = NativeMethods.FFMS_GetFrameByTime(_nativePtr, time, ref err);
}
if (framePtr == IntPtr.Zero)
{
throw new NotImplementedException(string.Format(System.Globalization.CultureInfo.CurrentCulture, "Unknown FFMS2 error encountered: ({0}, {1}, '{2}'). Please report this issue on FFMSSharp's GitHub.", err.ErrorType, err.SubType, err.Buffer));
}
LastFrame = new Frame(framePtr);
return LastFrame;
}