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• Node.js Stream Mp3 to http without having to save file

  21 août 2016, par user2758113

  I am trying to stream just audio from a youtube link straight to http with node.js.

  My code looks like this, I am using express 4.0.

  var express = require('express');
  
  var router = express.Router();
  
  var ytdl = require('ytdl');
  
  var ffmpeg = require('fluent-ffmpeg');
  
  var fs = require('fs');
  
  
  
  router.get('/', function(req, res) {
  
  
  
    var url = 'https://www.youtube.com/watch?v=GgcHlZsOgQo';
  
    var video = ytdl(url)
  
  
  
    res.set({
  
        "Content-Type": "audio/mpeg"
  
    })
  
  
  
    new ffmpeg({source: video})
  
        .toFormat('mp3')
  
        .writeToStream(res, function(data, err) {
  
          if (err) console.log(err)
  
        })
  
  
  
  });
  
  
  
  module.exports = router;

  Now, I’m able to stream the video’s audio to the response if I save the file then pipe it to the response, but I’d rather try to figure out some way to go from downloading to ffmpeg to response.

  Not sure if this is possible. The main goal is to keep it as light weight as possible, and not have to read from files.

  I’ve seen this code which is essentially what I’d like to do minus the saving to a file part.

  

• attempting to save FuncAnimation changes the animation

  25 mars 2024, par pibion

  I am attempting to create and save an animation of a time-varying vector field using matplotlib's FuncAnimation. When I run the animation without attempting to save it, it updates smoothly as expected. However, when I try to save the animation, the vectors increase in length and the animation only appears to update a few times. I've been able to record the screen to get a video file, but I'd like to understand how to save the animation to a video in python.

  


  Here is the code to create the vector field animation. I ran this in a local jupyter notebook using python 3.9.12 on Windows.

  


  %matplotlib notebook
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation

x_min, x_max = -20, 20
y_min, y_max = 0, 25
wire_x = -4
wire_y = 17

# Define the vector field function (example: rotating vector field)
def vector_field(x, y, t):
    x = x - wire_x
    y = y - wire_y
    r = np.sin(t) / (x**2 + y**2)
    u = -r * y
    v = r * x
    return (u, v)

# Define grid
x = np.linspace(x_min, x_max, 20)
y = np.linspace(y_min, y_max, 20)
X, Y = np.meshgrid(x, y)

# Create animation
fig, ax = plt.subplots(1,1)
ax.set_aspect('equal')
ax.set_xlim(x_min, x_max)
ax.set_ylim(y_min, y_max)
ax.set_xlabel('X (m)')
ax.set_ylabel('Y (m)')

u, v = vector_field(X, Y, 1)

quiver = ax.quiver(X, Y, u, v)

time_arr = np.linspace(0,20,200)

plt.show()

def update_quiver(num):
    t = num * 0.1  # Time step
    u, v = vector_field(X, Y, t)
    quiver.set_UVC(u, v)

ani = animation.FuncAnimation(fig, update_quiver, frames=200, interval=50, repeat=False)


  


  This produces an animation whose vectors smoothly vary in length on my computer.

  


  However, when I try to save the animation by adding the lines

  


  writervideo = animation.FFMpegWriter(fps=60) 
ani.save('field_leftWire.mp4', writer=writervideo) 


  


  then the animation changes - the vectors are much longer and it appears to only update a few times throughout the animation.

  


  I'll also note that I had to install ffmpeg and restart my computer as outlined in Installation of FFMPEG for Python in WIndows to get the last two lines to run without error.

  


• ffmpeg –i /data/1.mp4 /data/2.mp4 Unable to find a suitable output format for '–i' [duplicate]

  17 octobre 2016, par D.jia

  This question already has an answer here :

  • ffmpeg : Unable to find a suitable output format for ’–i’
    
    1 answer
    

  I have installed ffmpeg ,why doesn’t it work when I enter

  ffmpeg –i /data/1.mp4 /data/2.mp4 ??

  Could someone help me to solve it !