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• How to set background transparency for animation with ffmpeg

  23 octobre 2023, par Jan Turowski

  I am creating animated physics graphs with a transparent background for later use in a NLE. On my old machine at work they display and render with background transparency just fine. The exact same code however loses background transparency in the ffmpeg render on both my Linux and my Windows machine at home. The animations are displayed just fine on all machines.

  


  As I first thought it was a Linux issue, I tried to run the code on my Windows machine expecting it to work again. Unfortunately it did not.

  


  Reduced code :

  


  import numpy as np
import matplotlib.pylab as plt
from matplotlib.animation import FuncAnimation
import matplotlib.animation as animation
from matplotlib.pyplot import figure
from matplotlib import style
import locale
from matplotlib.ticker import (MultipleLocator, AutoMinorLocator)
# Set to German locale to get comma decimal separater
locale.setlocale(locale.LC_NUMERIC, "de_DE")
# Tell matplotlib to use the locale we set above
plt.rcParams['axes.formatter.use_locale'] = True

# plt.clf()
# plt.rcdefaults()

# Style und Font definieren

style.use('dark_background')

# Pfeile erstellen
def arrowed_spines(fig, ax):

    xmin, xmax = ax.get_xlim()
    ymin, ymax = ax.get_ylim()

    # removing the default axis on all sides:
    for side in ['bottom','right','top','left']:
        ax.spines[side].set_visible(False)

    # removing the axis ticks
    # plt.xticks([]) # labels
    # plt.yticks([])
    # ax.xaxis.set_ticks_position('none') # tick markers
    # ax.yaxis.set_ticks_position('none')

    # get width and height of axes object to compute
    # matching arrowhead length and width
    dps = fig.dpi_scale_trans.inverted()
    bbox = ax.get_window_extent().transformed(dps)
    width, height = bbox.width, bbox.height

    # manual arrowhead width and length
    hw = 1./20.*(ymax-ymin)
    hl = 1./20.*(xmax-xmin)
    lw = 1. # axis line width
    ohg = 0.3 # arrow overhang

    # compute matching arrowhead length and width
    yhw = hw/(ymax-ymin)*(xmax-xmin)* height/width
    yhl = hl/(xmax-xmin)*(ymax-ymin)* width/height

    # draw x and y axis
    ax.arrow(xmin, 0, xmax-xmin, 0., fc='w', ec='w', lw = lw,
             head_width=hw, head_length=hl, overhang = ohg,
             length_includes_head= True, clip_on = False)

    ax.arrow(0, ymin, 0., ymax-ymin, fc='w', ec='w', lw = lw,
             head_width=yhw, head_length=yhl, overhang = ohg,
             length_includes_head= True, clip_on = False)

# Meine easing-Funktion
def ease(n):
    if n < 0.0:
        return 0
    elif n > 1.0:
        return 1
    else:
        return 3*n**2-2*n**3

# Meine Floor/Warte Funktion
def wait(n):
    if n < 0.0:
        return 0
    else:
        return n

# Canvas erstellen
fig = plt.figure()
ax = fig.add_subplot(111)
fig.set_size_inches([8,9])

def f(x):
    return -0.05*x**2+125
xlin = np.linspace(0,60,100)


# Beschriftung und Optik

plt.xlabel(r"$x$ in $\rm{m}$", horizontalalignment='right', x=1.0)
plt.ylabel(r"$y$ in $\rm{m}$", horizontalalignment='right', y=1.0)
ax.set_xlim(0,100)
ax.set_ylim(0,139)
plt.grid(alpha=.4)
plt.xticks(np.arange(0, 100, 20))
plt.yticks(np.arange(0, 140, 20))
ax.yaxis.set_minor_locator(MultipleLocator(10))
ax.xaxis.set_minor_locator(MultipleLocator(10))
ax.tick_params(axis='x', direction = "inout", length= 10.0, which='both', width=3)
ax.tick_params(axis='y', direction = "inout", length= 10.0, which='both', width=3)


xsub = np.array([0])

# statische Linien definieren
line2, = ax.plot(xsub,f(xsub),linewidth=5,zorder=0,c = 'b')
arrowed_spines(fig, ax)
plt.tight_layout()

# Linien animieren
def animate(i):

    xsub = xlin[0:wait(i-20)]
    global line2
    line2.remove()
    line2, = ax.plot(xsub, f(xsub), linewidth=5, zorder=0,c = "b")
    plt.tight_layout()

animation = FuncAnimation(fig, animate, np.arange(0, 130, 1), interval=100)

plt.show()

# animation.save(r"YOUR\PATH\HERE\reduced_x-y.mov", codec="png",
         dpi=100, bitrate=-1,
         savefig_kwargs={'transparent': True, 'facecolor': 'none'})



  


• Background transparency lost on new machine using matplotlib and ffmpeg

  23 octobre 2023, par Jan Turowski

  I am creating animated physics graphs with a transparent background for later use in a NLE. On my old machine at work they display and render with background transparency just fine. The exact same code however loses background transparency in the ffmpeg render on both my Linux and my Windows machine at home. The animations are displayed just fine on all machines.

  


  As I first thought it was a Linux issue, I tried to run the code on my Windows machine expecting it to work again. Unfortunately it did not.

  


  Reduced code :

  


  import numpy as np
import matplotlib.pylab as plt
from matplotlib.animation import FuncAnimation
import matplotlib.animation as animation
from matplotlib.pyplot import figure
from matplotlib import style
import locale
from matplotlib.ticker import (MultipleLocator, AutoMinorLocator)
# Set to German locale to get comma decimal separater
locale.setlocale(locale.LC_NUMERIC, "de_DE")
# Tell matplotlib to use the locale we set above
plt.rcParams['axes.formatter.use_locale'] = True

# plt.clf()
# plt.rcdefaults()

# Style und Font definieren

style.use('dark_background')

# Pfeile erstellen
def arrowed_spines(fig, ax):

    xmin, xmax = ax.get_xlim()
    ymin, ymax = ax.get_ylim()

    # removing the default axis on all sides:
    for side in ['bottom','right','top','left']:
        ax.spines[side].set_visible(False)

    # removing the axis ticks
    # plt.xticks([]) # labels
    # plt.yticks([])
    # ax.xaxis.set_ticks_position('none') # tick markers
    # ax.yaxis.set_ticks_position('none')

    # get width and height of axes object to compute
    # matching arrowhead length and width
    dps = fig.dpi_scale_trans.inverted()
    bbox = ax.get_window_extent().transformed(dps)
    width, height = bbox.width, bbox.height

    # manual arrowhead width and length
    hw = 1./20.*(ymax-ymin)
    hl = 1./20.*(xmax-xmin)
    lw = 1. # axis line width
    ohg = 0.3 # arrow overhang

    # compute matching arrowhead length and width
    yhw = hw/(ymax-ymin)*(xmax-xmin)* height/width
    yhl = hl/(xmax-xmin)*(ymax-ymin)* width/height

    # draw x and y axis
    ax.arrow(xmin, 0, xmax-xmin, 0., fc='w', ec='w', lw = lw,
             head_width=hw, head_length=hl, overhang = ohg,
             length_includes_head= True, clip_on = False)

    ax.arrow(0, ymin, 0., ymax-ymin, fc='w', ec='w', lw = lw,
             head_width=yhw, head_length=yhl, overhang = ohg,
             length_includes_head= True, clip_on = False)

# Meine easing-Funktion
def ease(n):
    if n < 0.0:
        return 0
    elif n > 1.0:
        return 1
    else:
        return 3*n**2-2*n**3

# Meine Floor/Warte Funktion
def wait(n):
    if n < 0.0:
        return 0
    else:
        return n

# Canvas erstellen
fig = plt.figure()
ax = fig.add_subplot(111)
fig.set_size_inches([8,9])

def f(x):
    return -0.05*x**2+125
xlin = np.linspace(0,60,100)


# Beschriftung und Optik

plt.xlabel(r"$x$ in $\rm{m}$", horizontalalignment='right', x=1.0)
plt.ylabel(r"$y$ in $\rm{m}$", horizontalalignment='right', y=1.0)
ax.set_xlim(0,100)
ax.set_ylim(0,139)
plt.grid(alpha=.4)
plt.xticks(np.arange(0, 100, 20))
plt.yticks(np.arange(0, 140, 20))
ax.yaxis.set_minor_locator(MultipleLocator(10))
ax.xaxis.set_minor_locator(MultipleLocator(10))
ax.tick_params(axis='x', direction = "inout", length= 10.0, which='both', width=3)
ax.tick_params(axis='y', direction = "inout", length= 10.0, which='both', width=3)


xsub = np.array([0])

# statische Linien definieren
line2, = ax.plot(xsub,f(xsub),linewidth=5,zorder=0,c = 'b')
arrowed_spines(fig, ax)
plt.tight_layout()

# Linien animieren
def animate(i):

    xsub = xlin[0:wait(i-20)]
    global line2
    line2.remove()
    line2, = ax.plot(xsub, f(xsub), linewidth=5, zorder=0,c = "b")
    plt.tight_layout()

animation = FuncAnimation(fig, animate, np.arange(0, 130, 1), interval=100)

plt.show()

# animation.save(r"YOUR\PATH\HERE\reduced_x-y.mov", codec="png",
         dpi=100, bitrate=-1,
         savefig_kwargs={'transparent': True, 'facecolor': 'none'})



  


• How to crop and scale multiple landscape regions into a new portrait video ? FFmpeg

  27 août 2023, par 3V1LXD

  I have an electron program that selects multiple regions of a landscape video and lets you rearrange them in a portrait canvas. I'm having trouble building the proper ffmpeg command to create the video. I have this somewhat working. I can export 2 layers, but i can't export if i only have 1 layer or if i have 3 or more layers selected.

  


  2 regions of video selected

  


  layers [
  { top: 0, left: 658, width: 576, height: 1080 },
  { top: 262, left: 0, width: 576, height: 324 }
]
newPositions [
  { top: 0, left: 0, width: 576, height: 1080 },
  { top: 0, left: 0, width: 576, height: 324 }
]
filtergraph [0]crop=576:1080:658:0,scale=576:1080[v0];[0]crop=576:324:0:262,scale=576:324[v1];[v0][v1]overlay=0:0:0:0[out]

No Error export successful


  


  1 region selected

  


  layers [ { top: 0, left: 650, width: 576, height: 1080 } ]
newPositions [ { top: 0, left: 0, width: 576, height: 1080 } ]
filtergraph [0]crop=576:1080:650:0,scale=576:1080[v0];[v0]overlay=0:0[out]

FFmpeg error: [fc#0 @ 000001dd3b6db0c0] Cannot find a matching stream for unlabeled input pad overlay
Error initializing complex filters: Invalid argument


  


  3 regions of video selected

  


  layers [
  { top: 0, left: 641, width: 576, height: 1080 },
  { top: 250, left: 0, width: 576, height: 324 },
  { top: 756, left: 0, width: 576, height: 324 }
]
newPositions [
  { top: 0, left: 0, width: 576, height: 1080 },
  { top: 0, left: 0, width: 576, height: 324 },
  { top: 756, left: 0, width: 576, height: 324 }
]
filtergraph [0]crop=576:1080:641:0,scale=576:1080[v0];[0]crop=576:324:0:250,scale=576:324[v1];[0]crop=576:324:0:756,scale=576:324[v2];[v0][v1][v2]overlay=0:0:0:0:0:756[out]

FFmpeg error: [AVFilterGraph @ 0000018faf2189c0] More input link labels specified for filter 'overlay' than it has inputs: 3 > 2
[AVFilterGraph @ 0000018faf2189c0] Error linking filters

FFmpeg error: Failed to set value '[0]crop=576:1080:698:0,scale=576:1080[v0];[0]crop=576:324:0:264,scale=576:324[v1];[0]crop=576:324:0:756,scale=576:324[v2];[v0][v1][v2]overlay=0:0:0:0:0:0[out]' for option 'filter_complex': Invalid argument
Error parsing global options: Invalid argument


  


  I can't figure out how to construct the proper overlay command. Here is the js code i'm using from my electron app.

  


  ipcMain.handle('export-video', async (_event, args) => {
  const { videoFile, outputName, layers, newPositions } = args;
  const ffmpegPath = path.join(__dirname, 'bin', 'ffmpeg');
  const outputDir = checkOutputDir();
  
  // use same video for each layer as input
  // crop, scale, and position each layer
  // overlay each layer on top of each other

  // export video
  console.log('layers', layers);
  console.log('newPositions', newPositions);

  let filtergraph = '';

  for (let i = 0; i < layers.length; i++) {
    const { top, left, width, height } = layers[i];
    const { width: newWidth, height: newHeight } = newPositions[i];
    const filter = `[0]crop=${width}:${height}:${left}:${top},scale=${newWidth}:${newHeight}[v${i}];`;
    filtergraph += filter;
  }

  for (let i = 0; i < layers.length; i++) {
    const filter = `[v${i}]`;
    filtergraph += filter;
  }

  filtergraph += `overlay=`;
  for (let i = 0; i < layers.length; i++) {
    const { top: newTop, left: newLeft } = newPositions[i];
    const overlay = `${newLeft}:${newTop}:`;
    filtergraph += overlay;
  }

  filtergraph = filtergraph.slice(0, -1); // remove last comma
  filtergraph += `[out]`;
  
  console.log('filtergraph', filtergraph);

  const ffmpeg = spawn(ffmpegPath, [
    '-i', videoFile,
    '-filter_complex', filtergraph,
    '-map', '[out]',
    '-c:v', 'libx264',
    '-preset', 'ultrafast',
    '-crf', '18',
    '-y',
    path.join(outputDir, `${outputName}`)
  ]);  

  ffmpeg.stdout.on('data', (data) => {
    console.log(`FFmpeg output: ${data}`);
  });

  ffmpeg.stderr.on('data', (data) => {
    console.error(`FFmpeg error: ${data}`);
  });

  ffmpeg.on('close', (code) => {
    console.log(`FFmpeg process exited with code ${code}`);
    // event.reply('ffmpeg-export-done'); // Notify the renderer process
  });
});


  


  Any advice might be helpful, The docs are confusing, Thanks.