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• how to explain this C language code from ffmpeg remuxing

  20 avril 2017, par Fidona

  can someone help me what the meaning of this code ? this is a code from ffmpeg remuxing code.

  static void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt, const char *tag, int hours, int mins, int secs, int us, int *time )
  
  {
  
      AVRational *time_base = &fmt_ctx->streams[pkt->stream_index]->time_base;
  
      total = total + pkt->duration;
  
    //  printf( "%d:%d:%d.%d \n", hours,  mins,  secs, us );
  
      *time = av_q2d(*time_base) * pkt->pts ;
  
  }

  I’m kind of new to C language. thank you !

• Is there another way to export a frame in ffmpeg to a texture2d ? My code working in Windows but not Linux

  5 décembre 2024, par Robert Russell

  Sound is working in Linux the same as it did in Windows. But the video is just a black screen and when I attempt to save the frames as BMP files all of them were corrupt/empty files. I am using Ffmpeg.Autogen to interface with the libraries. https://github.com/Ruslan-B/FFmpeg.AutoGen. The file is VP8 and OGG in a MKV container. Though the extension is AVI for some reason.

  



  I tried messing with the order of the code a bit. I checked to make sure the build of Ffmpeg on Linux had VP8. I was searching online but was having trouble finding another way to do what I am doing. This is to contribute to the OpenVIII project. My fork-> https://github.com/Sebanisu/OpenVIII

  



  This just preps the scaler to change the pixelformat or else people have blue faces.

  



          private void PrepareScaler()
        {

            if (MediaType != AVMediaType.AVMEDIA_TYPE_VIDEO)
            {
                return;
            }

            ScalerContext = ffmpeg.sws_getContext(
                Decoder.CodecContext->width, Decoder.CodecContext->height, Decoder.CodecContext->pix_fmt,
                Decoder.CodecContext->width, Decoder.CodecContext->height, AVPixelFormat.AV_PIX_FMT_RGBA,
                ffmpeg.SWS_ACCURATE_RND, null, null, null);
            Return = ffmpeg.sws_init_context(ScalerContext, null, null);

            CheckReturn();
        }


  



  Converts Frame to BMP
I am thinking this is where the problem is. Because I had added bitmap.save to this and got empty BMPs.

  



  public Bitmap FrameToBMP()
        {
            Bitmap bitmap = null;
            BitmapData bitmapData = null;

            try
            {
                bitmap = new Bitmap(Decoder.CodecContext->width, Decoder.CodecContext->height, PixelFormat.Format32bppArgb);
                AVPixelFormat v = Decoder.CodecContext->pix_fmt;

                // lock the bitmap
                bitmapData = bitmap.LockBits(new Rectangle(0, 0, Decoder.CodecContext->width, Decoder.CodecContext->height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);

                byte* ptr = (byte*)(bitmapData.Scan0);

                byte*[] srcData = { ptr, null, null, null };
                int[] srcLinesize = { bitmapData.Stride, 0, 0, 0 };

                // convert video frame to the RGB bitmap
                ffmpeg.sws_scale(ScalerContext, Decoder.Frame->data, Decoder.Frame->linesize, 0, Decoder.CodecContext->height, srcData, srcLinesize); //sws_scale broken on linux?
            }
            finally
            {
                if (bitmap != null && bitmapData != null)
                {
                    bitmap.UnlockBits(bitmapData);
                }
            }
            return bitmap;

        }


  



  After I get a bitmap we turn it into a Texture2D so we can draw it.

  



   public Texture2D FrameToTexture2D()
        {
            //Get Bitmap. there might be a way to skip this step.
            using (Bitmap frame = FrameToBMP())
            {
                //string filename = Path.Combine(Path.GetTempPath(), $"{Path.GetFileNameWithoutExtension(DecodedFileName)}_rawframe.{Decoder.CodecContext->frame_number}.bmp");

                //frame.Save(filename);
                BitmapData bmpdata = null;
                Texture2D frameTex = null;
                try
                {
                    //Create Texture
                    frameTex = new Texture2D(Memory.spriteBatch.GraphicsDevice, frame.Width, frame.Height, false, SurfaceFormat.Color); //GC will collect frameTex
                                                                                                                                        //Fill it with the bitmap.
                    bmpdata = frame.LockBits(new Rectangle(0, 0, frame.Width, frame.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);// System.Drawing.Imaging.PixelFormat.Format32bppArgb);
                    byte[] texBuffer = new byte[bmpdata.Width * bmpdata.Height * 4]; //GC here
                    Marshal.Copy(bmpdata.Scan0, texBuffer, 0, texBuffer.Length);

                    frameTex.SetData(texBuffer);


                }
                finally
                {
                    if (bmpdata != null)
                    {
                        frame.UnlockBits(bmpdata);
                    }
                }
                return frameTex;

            }
        }


  



  I can post more if you want it's pretty much all up on my fork

  



  Video will play back as it does in Windows. As smooth as 15 fps can be. :)

  


• KeyError : 1 on Python when the code points to a value that exists [closed]

  10 décembre 2020, par oo92

  I am using the following code to traverse a list JSON output. There are about 100 streamers I want to take screens from but the code fails after the first one where I call the ffmpeg. I put a code after the ffmpeg to see if Python is running it at all and it does :

  


  Traceback (most recent call last):&#xA;  File "/home/onur/Desktop/pythonProject/main.py", line 12, in <module>&#xA;    username = streams_now[i][&#x27;channel&#x27;][&#x27;display_name&#x27;]&#xA;KeyError: 1&#xA;auronplay it is &#xA;</module>

  


  This is my code :

  


  import streamlink, os
from twitch import TwitchClient

client = TwitchClient(client_id='frl3dqgn21bbpp6tajjvg5pdevczac')

streams_now = client.streams.get_live_streams(limit=100)

print(streams_now[2]['channel']['display_name'])

for i in range(0, 99):
  username = streams_now[i]['channel']['display_name']
  streams_now = streamlink.streams('http://twitch.tv/' + username)
  stream = streams_now["best"].url
  dir_path = os.getcwd() + '/' + username
  os.mkdir(dir_path)
  os.system('ffmpeg -i ' + stream + f' -ss 20 -vframes 10 -r 0.2 -f image2 {dir_path}/' + username + '_output_%09d.jpg')
  print(username + ' it is ')


  


  The line that throws the error is username = streams_now[i]['channel']['display_name']. However, this line cannot throw an error because I am testing it before the for loop :

  


  print(streams_now[2]['channel']['display_name'])

  


  and I get this : shroud