/// <summary>
/// Initializes a new instance of the <see cref="AVIOContext"/> class.
/// </summary>
/// <param name="ffmpeg">
/// An implementation of the <see cref="FFmpegClient"/> interface which provides access to the
/// native FFmpeg functions.
/// </param>
/// <param name="bufferSize">
/// The buffer size.
/// </param>
/// <param name="read_packet">
/// A function for refilling the buffer, may be NULL. For stream protocols, must never return 0 but rather a proper AVERROR code.
/// </param>
/// <param name="write_packet">
/// A function for writing the buffer contents, may be NULL. The function may not change the input buffers content.
/// </param>
public AVIOContext(FFmpegClient ffmpeg, ulong bufferSize, NativeReadPacketFunc read_packet, NativeWritePacketFunc?write_packet)
{
this.ffmpeg = ffmpeg;
void *memory = ffmpeg.AllocMemory(bufferSize);
var memoryHandle = new AVMemoryHandle(ffmpeg, memory, false);
var avio_ctx = ffmpeg.AllocAVIOContext((byte *)memory, (int)bufferSize, write_packet == null ? 0 : 1, (void *)IntPtr.Zero, read_packet, write_packet.GetValueOrDefault(), null);
this.buffer = memoryHandle;
this.handle = new AVIOContextHandle(ffmpeg, avio_ctx);
}
/// <summary>
/// Decodes the current stream and blocks until decoding is done.
/// </summary>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken"/> which can be used to cancel the asynchronous operation.
/// </param>
public virtual unsafe void Decode(CancellationToken cancellationToken = default)
{
if (this.disposed)
{
throw new ObjectDisposedException(nameof(H264Decoder));
}
var readDelegate = new NativeReadPacket(this.Read);
var readFunc = new NativeReadPacketFunc()
{
Pointer = Marshal.GetFunctionPointerForDelegate(readDelegate),
};
using (var ioContext = new AVIOContext(this.client, ReadBufferSize, readFunc, null))
using (var formatContext = new AVFormatContext(this.client, ioContext))
{
formatContext.OpenInputStream("h264");
var stream = formatContext.GetVideoStream();
using (var codec = new AVCodec(this.client, stream))
using (var frame = new AVFrame(this.client))
using (var packet = new AVPacket(this.client))
{
int frameNumber = 0;
while (packet.ReadFrame(formatContext))
{
this.logger.LogDebug($"Got a frame for stream {packet.StreamIndex}");
if (packet.NativeObject->stream_index != stream.Index)
{
continue;
}
this.logger.LogDebug("Sending packet");
codec.SendPacket(packet);
int framesInPacket = 0;
while (codec.ReceiveFrame(frame))
{
this.logger.LogDebug("Receiving frame");
framesInPacket += 1;
if (frame.PictureType != NativeAVPictureType.AV_PICTURE_TYPE_NONE)
{
this.logger.LogDebug($"Got a picture of {frame.Width}x{frame.Height} in color space {frame.Format}");
// decode frame
this.FrameBuffer.DecompresFrame(
frame.Width,
frame.Height,
frame.Width,
frame.Height,
frame.Width * 4,
new Span <byte>(frame.NativeObject->data[0], frame.NativeObject->linesize[0]),
new Span <byte>(frame.NativeObject->data[1], frame.NativeObject->linesize[1]),
new Span <byte>(frame.NativeObject->data[2], frame.NativeObject->linesize[2]),
new int[] { frame.NativeObject->linesize[0], frame.NativeObject->linesize[1], frame.NativeObject->linesize[2] });
}
}
this.logger.LogInformation($"Add {framesInPacket} frames in packet.");
frameNumber++;
}
}
}
GC.KeepAlive(readDelegate);
}
