Recherche avancée

Sur d’autres sites (14149)

• ffmpeg process how to read from pipe to pipe in c#

  28 janvier 2024, par greg

  I need to read audio data from stream 1 to stream 2 passing the data through ffmpeg.
It works great when i input data from file and output to pipe :

  


  Process? CreateStream()
{
    return Process.Start(new ProcessStartInfo
    {
        FileName = @"sources\ffmpeg",
        Arguments = @"-i input.mp3 -f s16le pipe:1",
        UseShellExecute = false,
        RedirectStandardOutput = true
    });
}


  


  Or when i input data from pipe and output to file :

  


  Process? CreateStream()
{
    return Process.Start(new ProcessStartInfo
    {
        FileName = @"sources\ffmpeg",
        Arguments = @"-i pipe: -f s16le output.file",
        UseShellExecute = false,
        RedirectStandardInput = true
    });
}


  


  But if i try to do both :

  


  Process? CreateStream()
{
    return Process.Start(new ProcessStartInfo
    {
        FileName = @"sources\ffmpeg",
        Arguments = @"-i pipe:0 -f s16le pipe:1",
        UseShellExecute = false,
        RedirectStandardInput = true,
        RedirectStandardOutput = true
    });
}


  


  Runtime will hang in place printing :

  


  


  Input #0, matroska,webm, from 'pipe:0' :
Metadata :
encoder : google/video-file
Duration : 00:04:15.38, start : -0.007000, bitrate : N/A
Stream #0:0(eng) : Audio : opus, 48000 Hz, stereo, fltp (default)
Stream mapping :
Stream #0:0 -> #0:0 (opus (native) -> pcm_s16le (native))

  


  Output #0, s16le, to 'pipe:1' :
Metadata :
encoder : Lavf59.27.100
Stream #0:0(eng) : Audio : pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s (default)
Metadata :
encoder : Lavc59.37.100 pcm_s16le

  


  


  main function code (it is the same for all examples) :

  


  async Task Do()
{
    using (var ffmpeg = CreateStream())
    {
        if (ffmpeg == null) return;

        using (var audioStream = GetAudioStream())
        {
            await audioStream.CopyToAsync(ffmpeg.StandardInput.BaseStream);
            ffmpeg.StandardInput.Close();
        }

        //runtime will hang in here

        Console.WriteLine("\n\ndone\n\n"); //this won't be printed

        using (var outputStream = CreatePCMStream())
        {
            try
            {
                await ffmpeg.StandardOutput.BaseStream.CopyToAsync(outputStream);
            }
            finally
            {
                await outputStream.FlushAsync();
            }
        }
    }
}


  


  And the most interesting is if i remove RedirectStandardOutput = true string programm will work as expected printing a bunch of raw data to the console.

  


  I'd like to solve this problem without using any intermediate files and so on.

  


• Matplotlib pipe canvas.draw() to ffmpeg - unexpected result [duplicate]

  31 juillet 2022, par Narusan

  I'm using this code from here to try and pipe multiple matplotlib plots into ffmpeg to write a video file :

  


  import numpy as np
import matplotlib.pyplot as plt
import subprocess

xlist = np.random.randint(100,size=100)
ylist = np.random.randint(100, size=100)
color = np.random.randint(2, size=100)

f = plt.figure(figsize=(5,5), dpi = 300)
canvas_width, canvas_height = f.canvas.get_width_height()
ax = f.add_axes([0,0,1,1])
ax.axis('off')


# Open an ffmpeg process
outf = 'ffmpeg.mp4'
cmdstring = ('ffmpeg',
    '-y', '-r', '30', # overwrite, 30fps
    '-s', '%dx%d' % (canvas_width, canvas_height), # size of image string
    '-pix_fmt', 'argb', # format
    '-f', 'rawvideo',  '-i', '-', # tell ffmpeg to expect raw video from the pipe
    '-vcodec', 'mpeg4', outf) # output encoding
p = subprocess.Popen(cmdstring, stdin=subprocess.PIPE)

# Draw 1000 frames and write to the pipe
for frame in range(10):
    print("Working on frame")
    # draw the frame
    f = plt.figure(figsize=(5,5), dpi=300)
    ax = f.add_axes([0,0,1,1])
    ax.scatter(xlist, ylist,
               c=color, cmap = 'viridis')
    f.canvas.draw()
    plt.show()

    # extract the image as an ARGB string
    string = f.canvas.tostring_argb()
    # write to pipe
    p.stdin.write(string)

# Finish up
p.communicate()


  


  While plt.show() does show the correct plot (see image below), the video that ffmpeg creates is a bit different than what plt.show() shows. I am presuming the issue is with f.canvas.draw(), but I'm not sure how to get a look at what canvas.draw() actually plots.

  


  plot.show() :


  


  ffmpeg video (imgur link)

  


• PortAudio pipe ffmpeg

  11 juillet 2022, par DNS

  I would like to get the buffer from PortAudio and in real time (each seconds for example) to send it to ffmpeg to make it streamable. I'm trying to capture the microphone buffer to send it to ffmpeg.

  


  Actually I get my PortAudio buffer :

  


  std::vector<unsigned short="short"> captured(bufferSize * channels);&#xA;std::vector<unsigned short="short"> saveCaptured;&#xA;&#xA;while (framesProcessed &lt; sampleRate * durationSeconds)&#xA;{&#xA;    if ((paErr = Pa_ReadStream(stream, captured.data(), bufferSize)) != paNoError)&#xA;    {&#xA;        std::cout &lt;&lt; "Pa_ReadStream failed: " &lt;&lt; Pa_GetErrorText(paErr) &lt;&lt; "\n";&#xA;        return 1;&#xA;    }&#xA;    for (const auto&amp; value : captured) {&#xA;        saveCaptured.push_back(value);&#xA;    }&#xA;    framesProcessed &#x2B;= bufferSize;&#xA;}&#xA;</unsigned></unsigned>

  


  How can I send the buffer to ffmpeg ? I read somewhere that pcm data are readable with ffmpeg but my portaudio buffer cannot be read.

  


  I would like to know if I have to create a audio header to be understood by ffmpeg, can you confirm that I don't need any header ?