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• Play video using ffmpeg subprocess

  17 juin 2023, par MCD

  The following code stuck in the middle of the video. I want to play the video start at start_seconds and end at end_seconds.

  


  import subprocess
import cv2
import numpy as np
import subprocess

def play_video_with_ffmpeg(video_path, start_seconds, end_seconds):
print(start_seconds)

    # Set the desired frame size
    width = 920
    height = 600
    
    # Set the window position
    print("here")
    window_x = 600  # X position
    window_y = 10  # Y position
    cv2.namedWindow('Video Player', cv2.WINDOW_NORMAL)
    cv2.moveWindow('Video Player', window_x, window_y)
    
    # Build the ffmpeg command to skip to the desired start time and end time
    command = [
        'ffmpeg',
        '-ss', str(start_seconds),
        '-i', video_path,
        '-t', str((end_seconds - start_seconds)),
        '-vf', f'scale={width}:{height}',
        '-r', '30',
        '-f', 'image2pipe',
        '-pix_fmt', 'bgr24',
        '-vcodec', 'rawvideo',
        '-'
    ]
    
    # Open a subprocess to execute the ffmpeg command
    process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    
    # Create a buffer to hold the frame data
    buffer_size = width * height * 3
    frame_buffer = bytearray(buffer_size)
    
    while process.poll() is None:
        # Read the frame from the subprocess stdout into the buffer
        bytes_read = process.stdout.readinto(frame_buffer)
    
        if bytes_read == buffer_size:
            # Convert the frame buffer to a numpy array
            frame = np.frombuffer(frame_buffer, dtype='uint8').reshape((height, width, 3))
    
            # Resize the frame
            frame_resized = cv2.resize(frame, (width, height), interpolation=cv2.INTER_AREA)
    
            # Display the frame
            cv2.imshow('Video Player', frame_resized)
    
            if cv2.waitKey(1) & 0xFF == ord('q'):
                break
    
    process.stdout.close()
    process.stderr.close()
    cv2.destroyAllWindows()


  


  I expect to play the video start from start_second and end at end_second. I used cv2.set but it took long time to play from start_second.

  


• Could you please guide me on how to play a single sample of an audio file in C# using FFmpeg ?

  11 juillet 2023, par hello world

  What is the recommended approach for playing a single sample of an audio file in C# using FFmpeg ? I would like to incorporate FFmpeg into my C# application to play a specific sample from an audio file. Could someone provide an example or guide me on how to achieve this ? Any help would be appreciated.

  


  using System;
using System.Diagnostics;

public class AudioPlayer
{
    private string ffmpegPath;

    public AudioPlayer(string ffmpegPath)
    {
        this.ffmpegPath = ffmpegPath;
    }

    public void PlayAudioSample(string audioFilePath, TimeSpan samplePosition)
    {
        // Prepare FFmpeg process
        Process ffmpegProcess = new Process();
        ffmpegProcess.StartInfo.FileName = ffmpegPath;
        ffmpegProcess.StartInfo.Arguments = $"-ss {samplePosition} -i \"{audioFilePath}\" -t 1 -acodec pcm_s16le -f wav -";
        ffmpegProcess.StartInfo.RedirectStandardOutput = true;
        ffmpegProcess.StartInfo.RedirectStandardError = true;
        ffmpegProcess.StartInfo.UseShellExecute = false;
        ffmpegProcess.StartInfo.CreateNoWindow = true;

        // Start FFmpeg process
        ffmpegProcess.Start();

        // Play audio sample
        using (var audioOutput = new NAudio.Wave.WaveOutEvent())
        {
            using (var audioStream = new NAudio.Wave.RawSourceWaveStream(ffmpegProcess.StandardOutput.BaseStream, new NAudio.Wave.WaveFormat(44100, 16, 2)))
            {
                audioOutput.Init(audioStream);
                audioOutput.Play();
                while (audioOutput.PlaybackState == NAudio.Wave.PlaybackState.Playing)
                {
                    System.Threading.Thread.Sleep(100);
                }
            }
        }

        // Wait for FFmpeg process to exit
        ffmpegProcess.WaitForExit();
    }
}


  


• How to Play AVI file in a Loop

  10 octobre 2019, par sam

  I am using ffMpeg to play AVI file.

  This is my code where i am reading the frame..

  i define my structure

  typedef struct {
  
  
  
      AVFormatContext *fmt_ctx;
  
      int stream_idx;
  
      AVStream *video_stream;
  
      AVCodecContext *codec_ctx;
  
      AVCodec *decoder;
  
      AVPacket *packet;
  
      AVFrame *av_frame;
  
      AVFrame *gl_frame;
  
      struct SwsContext *conv_ctx;
  
      GLuint frame_tex;
  
  }AppData;

  This is how i read frame.

  bool readFrame(AppData *data)
  
  {
  
      do {
  
          if (av_read_frame(data->fmt_ctx, data->packet) < 0) {
  
              av_free_packet(data->packet);
  
              return false;
  
          }
  
  
  
          if (data->packet->stream_index == data->stream_idx)
  
          {
  
              int frame_finished = 0;
  
  
  
              if (avcodec_decode_video2(data->codec_ctx, data->av_frame, &frame_finished,
  
                  data->packet) < 0) {
  
                  av_free_packet(data->packet);
  
                  return false;
  
              }
  
  
  
              if (frame_finished)
  
              {
  
                  if (!data->conv_ctx)
  
                  {
  
                      data->conv_ctx = sws_getContext(data->codec_ctx->width,
  
                          data->codec_ctx->height, data->codec_ctx->pix_fmt,
  
                          data->codec_ctx->width, data->codec_ctx->height, AV_PIX_FMT_RGBA,
  
                          SWS_BICUBIC, NULL, NULL, NULL);
  
                  }
  
  
  
                  sws_scale(data->conv_ctx, data->av_frame->data, data->av_frame->linesize, 0,
  
                      data->codec_ctx->height, data->gl_frame->data, data->gl_frame->linesize);
  
  
  
                  glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, data->codec_ctx->width,
  
                      data->codec_ctx->height, GL_RGBA, GL_UNSIGNED_BYTE,
  
                      data->gl_frame->data[0]);
  
  
  
              }
  
  
  
          }
  
          av_free_packet(data->packet);
  
  
  
      } while (data->packet->stream_index != data->stream_idx);
  
  
  
      return true;
  
  
  
  } 

  1. Currently the video plays and stops at the last frame, how can I reset the frame number to start frame once the whole video is played.
  2. How can I play the video by passing the frame number instead of automatic loop ?