BMP processing

[m1adow]

Hello! I have a question. I am trying to encode and decode frames. On input, I have a 32 bit depth bmp but on output, I have 24 bit depth and in Format24bppRgb format. How to achieve 32 bit depth Bgra format using your library?

Encoding code

encoder = new CodecContext(Codec.FindEncoderById(AVCodecID.H264))
{
    Width = 1920,
    Height = 1080,
    Framerate = new AVRational(1, 30),
    TimeBase = new AVRational(1, 30),
    PixelFormat = AVPixelFormat.Yuv420p,
};

encoder.Open(null, new MediaDictionary
{
    ["crf"] = "30",
    ["tune"] = "zerolatency",
    ["preset"] = "veryfast"
});

rgbFrame.Width = 1920;
rgbFrame.Height = 1080;
rgbFrame.Format = (int)AVPixelFormat.Bgra;

yuvFrame.Width = 1920;
yuvFrame.Height = 1080;
yuvFrame.Format = (int)AVPixelFormat.Yuv420p;

unsafe
{
    fixed (byte* ptr = frame)
    {
        rgbFrame.Data[0] = (nint)ptr;
    }
}
rgbFrame.Linesize[0] = 7680;
rgbFrame.Pts = 0;

yuvFrame.EnsureBuffer();
yuvFrame.MakeWritable();
videoFrameConverter.ConvertFrame(rgbFrame, yuvFrame);
yuvFrame.Pts = 1;

var frames = new List<byte[]>();
foreach (var packet in encoder.EncodeFrame(yuvFrame, packetRef))
{
    frames.Add(packet.Data.AsSpan().ToArray());
}

Decoding code:

decoder = new CodecContext(Codec.FindDecoderById(AVCodecID.H264))
{
    Width = 1920,
    Height = 1080,
    PixelFormat = AVPixelFormat.Yuv420p,
};
decoder.Open();

var decodedFrames = new List<byte[]>();
foreach (var packetBytes in packets)
{
    unsafe
    {
        fixed (byte* bodyPtr = packetBytes)
        {
            AVPacket avPacket = default;
            _ = ffmpeg.av_packet_from_data(&avPacket, bodyPtr, packetBytes.Length);
            using var packet = Packet.FromNative(&avPacket, false);
            packet.Flags = 1;
            decoder.SendPacket(packet);
        }
    }

    var decodeResult = decoder.ReceiveFrame(yuvFrame);
    if (decodeResult == CodecResult.Success)
    {
        using var rgbFrame = new Frame()
        {
            Width = yuvFrame.Width,
            Height = yuvFrame.Height,
            Format = (int)AVPixelFormat.Bgra,
        };

        rgbFrame.EnsureBuffer();
        rgbFrame.MakeWritable();
        videoFrameConverter.ConvertFrame(yuvFrame, rgbFrame);

        var frame = rgbFrame.EncodeToBytes(formatName: "image2pipe");
        decodedFrames.Add(frame);
    }
}

So, what should I change in my code?