FFmpeg.Autogen: проблема с атомными блоками нулевого размера в выводе MP4

Я только начал изучать ffmpeg, используя оболочку ffmpeg.autogen версии 5.1 в C# и общие библиотеки ffmpeg версии 5.1. Я пытаюсь создать класс, который записывает экран с помощью gdigrab и создает потоковый mp4 в буфер/событие. Кажется, что все работает так, как и предполагалось, без ошибок, за исключением того, что выходной поток создает атомные блоки с размером 0, поэтому размер файла также небольшой, в полях не создается никаких данных, «отладочный тестовый файл mp4» анализируется с помощью MP4Box и Информация о коробке указана в теме.

Чтобы быть более конкретным, почему этот код создает пустые атомные блоки, может ли кто-нибудь сделать так, чтобы созданные данные действительно содержали какие-либо данные кадра из gdigrab, редактирующего мой код?

`код:

 public unsafe class ScreenStreamer : IDisposable
 {
     private readonly AVCodec* productionCodec;
     private readonly AVCodec* screenCaptureAVCodec;
     private readonly AVCodecContext* productionAVCodecContext;
     private readonly AVFormatContext* productionFormatContext;
     private readonly AVCodecContext* screenCaptureAVCodecContext;
     private readonly AVDictionary* productionAVCodecOptions;
     private readonly AVInputFormat* screenCaptureInputFormat;
     private readonly AVFormatContext* screenCaptureInputFormatContext;
     private readonly int gDIGrabVideoStreamIndex;
     private readonly System.Drawing.Size screenBounds;
     private readonly int _produceAtleastAmount;
     public EventHandler<byte[]> OnNewVideoDataProduced;
     private MemoryStream unsafeToManagedBridgeBuffer;
     private CancellationTokenSource cancellationTokenSource;
     private Task recorderTask;

     public ScreenStreamer(int fps, int bitrate, int screenIndex, int produceAtleastAmount = 1000)
     {
         ffmpeg.avdevice_register_all();
         ffmpeg.avformat_network_init();
         recorderTask = Task.CompletedTask;
         cancellationTokenSource = new CancellationTokenSource();
         unsafeToManagedBridgeBuffer = new MemoryStream();
         _produceAtleastAmount = produceAtleastAmount;

         // Allocate and initialize production codec and context
         productionCodec = ffmpeg.avcodec_find_encoder(AVCodecID.AV_CODEC_ID_H264);
         if (productionCodec == null) throw new ApplicationException("Could not find encoder for codec ID H264.");

         productionAVCodecContext = ffmpeg.avcodec_alloc_context3(productionCodec);
         if (productionAVCodecContext == null) throw new ApplicationException("Could not allocate video codec context.");

         // Set codec parameters
         screenBounds = RetrieveScreenBounds(screenIndex);
         productionAVCodecContext->width = screenBounds.Width;
         productionAVCodecContext->height = screenBounds.Height;
         productionAVCodecContext->time_base = new AVRational() { den = fps, num = 1 };
         productionAVCodecContext->pix_fmt = AVPixelFormat.AV_PIX_FMT_YUV420P;
         productionAVCodecContext->bit_rate = bitrate;

         int result = ffmpeg.av_opt_set(productionAVCodecContext->priv_data, "preset", "veryfast", 0);
         if (result != 0)
         {
             throw new ApplicationException($"Failed to set options with error code {result}.");
         }

         // Open codec
         fixed (AVDictionary** pm = &productionAVCodecOptions)
         {
             result = ffmpeg.av_dict_set(pm, "movflags", "frag_keyframe+empty_moov+default_base_moof", 0);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to set dictionary with error code {result}.");
             }

             result = ffmpeg.avcodec_open2(productionAVCodecContext, productionCodec, pm);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to open codec with error code {result}.");
             }
         }

         // Allocate and initialize screen capture codec and context
         screenCaptureInputFormat = ffmpeg.av_find_input_format("gdigrab");
         if (screenCaptureInputFormat == null) throw new ApplicationException("Could not find input format gdigrab.");

         fixed (AVFormatContext** ps = &screenCaptureInputFormatContext)
         {
             result = ffmpeg.avformat_open_input(ps, "desktop", screenCaptureInputFormat, null);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to open input with error code {result}.");
             }

             result = ffmpeg.avformat_find_stream_info(screenCaptureInputFormatContext, null);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to find stream info with error code {result}.");
             }
         }

         gDIGrabVideoStreamIndex = -1;
         for (int i = 0; i < screenCaptureInputFormatContext->nb_streams; i++)
         {
             if (screenCaptureInputFormatContext->streams[i]->codecpar->codec_type == AVMediaType.AVMEDIA_TYPE_VIDEO)
             {
                 gDIGrabVideoStreamIndex = i;
                 break;
             }
         }

         if (gDIGrabVideoStreamIndex < 0)
         {
             throw new ApplicationException("Failed to find video stream in input.");
         }

         AVCodecParameters* codecParameters = screenCaptureInputFormatContext->streams[gDIGrabVideoStreamIndex]->codecpar;
         screenCaptureAVCodec = ffmpeg.avcodec_find_decoder(codecParameters->codec_id);
         if (screenCaptureAVCodec == null)
         {
             throw new ApplicationException("Could not find decoder for screen capture.");
         }

         screenCaptureAVCodecContext = ffmpeg.avcodec_alloc_context3(screenCaptureAVCodec);
         if (screenCaptureAVCodecContext == null)
         {
             throw new ApplicationException("Could not allocate screen capture codec context.");
         }

         result = ffmpeg.avcodec_parameters_to_context(screenCaptureAVCodecContext, codecParameters);
         if (result < 0)
         {
             throw new ApplicationException($"Failed to copy codec parameters to context with error code {result}.");
         }

         result = ffmpeg.avcodec_open2(screenCaptureAVCodecContext, screenCaptureAVCodec, null);
         if (result < 0)
         {
             throw new ApplicationException($"Failed to open screen capture codec with error code {result}.");
         }
     }

     public void Start()
     {
         recorderTask = Task.Run(() =>
         {
             AVPacket* packet = ffmpeg.av_packet_alloc();
             AVFrame* rawFrame = ffmpeg.av_frame_alloc();
             AVFrame* compatibleFrame = null;
             byte* dstBuffer = null;

             try
             {
                 while (!cancellationTokenSource.Token.IsCancellationRequested)
                 {
                     if (ffmpeg.av_read_frame(screenCaptureInputFormatContext, packet) >= 0)
                     {
                         if (packet->stream_index == gDIGrabVideoStreamIndex)
                         {
                             int response = ffmpeg.avcodec_send_packet(screenCaptureAVCodecContext, packet);
                             if (response < 0)
                             {
                                 throw new ApplicationException($"Error while sending a packet to the decoder: {response}");
                             }

                             response = ffmpeg.avcodec_receive_frame(screenCaptureAVCodecContext, rawFrame);
                             if (response == ffmpeg.AVERROR(ffmpeg.EAGAIN) || response == ffmpeg.AVERROR_EOF)
                             {
                                 continue;
                             }
                             else if (response < 0)
                             {
                                 throw new ApplicationException($"Error while receiving a frame from the decoder: {response}");
                             }

                             compatibleFrame = ConvertToCompatiblePixelFormat(rawFrame, out dstBuffer);

                             response = ffmpeg.avcodec_send_frame(productionAVCodecContext, compatibleFrame);
                             if (response < 0)
                             {
                                 throw new ApplicationException($"Error while sending a frame to the encoder: {response}");
                             }

                             while (response >= 0)
                             {
                                 response = ffmpeg.avcodec_receive_packet(productionAVCodecContext, packet);
                                 if (response == ffmpeg.AVERROR(ffmpeg.EAGAIN) || response == ffmpeg.AVERROR_EOF)
                                 {
                                     break;
                                 }
                                 else if (response < 0)
                                 {
                                     throw new ApplicationException($"Error while receiving a packet from the encoder: {response}");
                                 }

                                 using var packetStream = new UnmanagedMemoryStream(packet->data, packet->size);
                                 packetStream.CopyTo(unsafeToManagedBridgeBuffer);
                                 byte[] managedBytes = unsafeToManagedBridgeBuffer.ToArray();
                                 OnNewVideoDataProduced?.Invoke(this, managedBytes);
                                 unsafeToManagedBridgeBuffer.SetLength(0);
                             }
                         }
                     }
                     ffmpeg.av_packet_unref(packet);
                     ffmpeg.av_frame_unref(rawFrame);
                     if (compatibleFrame != null)
                     {
                         ffmpeg.av_frame_unref(compatibleFrame);
                         ffmpeg.av_free(dstBuffer);
                     }
                 }
             }
             finally
             {
                 ffmpeg.av_packet_free(&packet);
                 ffmpeg.av_frame_free(&rawFrame);
                 if (compatibleFrame != null)
                 {
                     ffmpeg.av_frame_free(&compatibleFrame);
                 }
             }
         });
     }

     public AVFrame* ConvertToCompatiblePixelFormat(AVFrame* srcFrame, out byte* dstBuffer)
     {
         AVFrame* dstFrame = ffmpeg.av_frame_alloc();
         int buffer_size = ffmpeg.av_image_get_buffer_size(productionAVCodecContext->pix_fmt, productionAVCodecContext->width, productionAVCodecContext->height, 1);
         byte_ptrArray4 dstData = new byte_ptrArray4();
         int_array4 dstLinesize = new int_array4();
         dstBuffer = (byte*)ffmpeg.av_malloc((ulong)buffer_size);
         ffmpeg.av_image_fill_arrays(ref dstData, ref dstLinesize, dstBuffer, productionAVCodecContext->pix_fmt, productionAVCodecContext->width, productionAVCodecContext->height, 1);

         dstFrame->format = (int)productionAVCodecContext->pix_fmt;
         dstFrame->width = productionAVCodecContext->width;
         dstFrame->height = productionAVCodecContext->height;
         dstFrame->data.UpdateFrom(dstData);
         dstFrame->linesize.UpdateFrom(dstLinesize);

         SwsContext* swsCtx = ffmpeg.sws_getContext(
             srcFrame->width, srcFrame->height, (AVPixelFormat)srcFrame->format,
             productionAVCodecContext->width, productionAVCodecContext->height, productionAVCodecContext->pix_fmt,
             ffmpeg.SWS_BILINEAR, null, null, null);

         if (swsCtx == null)
         {
             throw new ApplicationException("Could not initialize the conversion context.");
         }

         ffmpeg.sws_scale(swsCtx, srcFrame->data, srcFrame->linesize, 0, srcFrame->height, dstFrame->data, dstFrame->linesize);
         ffmpeg.sws_freeContext(swsCtx);
         return dstFrame;
     }

     private System.Drawing.Size RetrieveScreenBounds(int screenIndex)
     {
         return new System.Drawing.Size(1920, 1080);
     }

     public void Dispose()
     {
         cancellationTokenSource?.Cancel();
         recorderTask?.Wait();
         cancellationTokenSource?.Dispose();
         recorderTask?.Dispose();
         unsafeToManagedBridgeBuffer?.Dispose();

         fixed (AVCodecContext** p = &productionAVCodecContext)
         {
             if (*p != null)
             {
                 ffmpeg.avcodec_free_context(p);
             }
         }
         fixed (AVCodecContext** p = &screenCaptureAVCodecContext)
         {
             if (*p != null)
             {
                 ffmpeg.avcodec_free_context(p);
             }
         }

         if (productionFormatContext != null)
         {
             ffmpeg.avformat_free_context(productionFormatContext);
         }

         if (screenCaptureInputFormatContext != null)
         {
             ffmpeg.avformat_free_context(screenCaptureInputFormatContext);
         }

         if (productionAVCodecOptions != null)
         {
             fixed (AVDictionary** p = &productionAVCodecOptions)
             {
                 ffmpeg.av_dict_free(p);
             }
         }
     }
 }

Я вызываю метод Start и жду 8 секунд. Я записываю байты в файл mp4 без использования трейлера записи только для отладки атомбоксов. и вывод окна отладки mp4, который я получил:

(ПОЛНЫЙ ВЫХОД) https://pastebin.com/xkM4MfG7

(Не полный)

"
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</AudioSampleDescriptionBox>
<TrackGroupTypeBox Size = "0" Type = "msrc" Version = "0" Flags = "0" Specification = "p12" Container = "trgr" track_group_id = "0">
</TrackGroupTypeBox>
<TrackGroupTypeBox Size = "0" Type = "ster" Version = "0" Flags = "0" Specification = "p12" Container = "trgr" track_group_id = "0">
</TrackGroupTypeBox>
<TrackGroupTypeBox Size = "0" Type = "cstg" Version = "0" Flags = "0" Specification = "p15" Container = "trgr" track_group_id = "0">
</TrackGroupTypeBox>
<FreeSpaceBox Size = "0" Type = "free" Specification = "p12" Container = "*" dataSize = "0">
</FreeSpaceBox>
<FreeSpaceBox Size = "0" Type = "free" Specification = "p12" Container = "*" dataSize = "0">
</FreeSpaceBox>
<MediaDataBox Size = "0" Type = "mdat" Specification = "p12" Container = "file" dataSize = "0">
</MediaDataBox>
<MediaDataBox Size = "0" Type = "mdat" Specification = "p12" Container = "meta" dataSize = "0">
"