private readonly Stream stream; // The underlying stream
/// <summary>
/// Initializes the structure with the appropriate delegates for
/// a stream.
/// </summary>
/// <param name="stream">The stream.</param>
public StreamDelegates(Stream stream)
{
this.stream = stream;
this.SetPos32 = new SetStreamPos32Delegate(SetPos32Handler);
this.GetPos32 = new GetStreamPos32Delegate(GetPos32Handler);
this.SetPos64 = new SetStreamPos64Delegate(SetPos64Handler);
this.GetPos64 = new GetStreamPos64Delegate(GetPos64Handler);
this.Write = new WriteStreamDelegate(WriteHandler);
this.Read = new ReadStreamDelegate(ReadHandler);
this.GetLength32 = new GetStreamLength32Delegate(GetLength32Handler);
this.SetLength32 = new SetStreamLength32Delegate(SetLength32Handler);
this.GetLength64 = new GetStreamLength64Delegate(GetLength64Handler);
this.SetLength64 = new SetStreamLength64Delegate(SetLength64Handler);
}
private void OpenInput()
{
formatContext = ffmpeg.avformat_alloc_context();
fixed(AVFormatContext **formatContextPtr = &formatContext)
{
int error;
AVInputFormat *inputFormat = null;
if (stream != null)
{
const int bufferSize = 8192;
// with delegates and anonymous functions, we can capture
// the local stream variable without passing it as a argument.
ReadStreamDelegate readStream = (IntPtr opaque, IntPtr buf, int buf_size) =>
{
byte[] array = new byte[buf_size];
int read = stream.Read(array, 0, buf_size);
Marshal.Copy(array, 0, buf, read);
return(read);
};
SeekStreamDelegate seekStream = (IntPtr opaque, Int64 offset, int whence) =>
{
if (whence == ffmpeg.AVSEEK_SIZE)
{
return(stream.Length);
}
if (!stream.CanSeek)
{
return(-1);
}
stream.Seek(offset, (SeekOrigin)whence);
return(stream.Position);
};
// track the delegates, GC might remove them prematurely
delegateRefs.Add(readStream);
delegateRefs.Add(seekStream);
// setup custom stream reader for ffmpeg to use with AVIO context
sbyte *readBuffer = (sbyte *)ffmpeg.av_malloc(bufferSize + ffmpeg.FF_INPUT_BUFFER_PADDING_SIZE);
avioContext = ffmpeg.avio_alloc_context(readBuffer, bufferSize, 0, null,
Marshal.GetFunctionPointerForDelegate(readStream), IntPtr.Zero,
Marshal.GetFunctionPointerForDelegate(seekStream));
formatContext->pb = avioContext;
formatContext->flags |= ffmpeg.AVFMT_FLAG_CUSTOM_IO;
if ((error = ffmpeg.av_probe_input_buffer(formatContext->pb, &inputFormat, path, null, 0, 0)) != 0)
{
throw new FFmpegException(error);
}
if (path != null && (inputFormat->flags & ffmpeg.AVFMT_NOFILE) != 0)
{
// Input format (image2) doesn't support custom AVIOContext,
// forcefully clear the flag and hope it works.
inputFormat->flags &= ~ffmpeg.AVFMT_NOFILE;
//ffmpeg.avio_close(formatContext->pb);
}
}
if ((error = ffmpeg.avformat_open_input(formatContextPtr, path, inputFormat, null)) != 0)
{
throw new FFmpegException(error, "Failed to open input stream for file '" + path + "'");
}
}
frame = ffmpeg.av_frame_alloc();
}