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• Saving highest quality video from video-capture card

  23 décembre 2013, par DusteD

  I have a machine with 2x3 3ghz dual-core xeon and 4x10krpm scsi 320 disks in raid0.
  The capture card is an osprey 560 64 bit pci card.
  Operating system is currently Windows Server 2003.

  The video-stream that I can open with VLC using direct show is rather nice quality.
  However, trying to save this video-stream without loss of quality has proven quite difficult,
  using the h264 codec I am able to achieve a satisfying quality, however, all 4 cores jump to 100% load after a few second and then it start dropping frames, the machine is not powerful enough for realtime encoding. I've not been able to achieve satisfying mpeg1 or 4 quality, no matter which bitrate I set..

  Thing is, the disks in this machine are pretty fast even by todays standard, and they are bored.. I don't care about disk-usage, I want quality.
  I have searched in vain for a way to pump that beautiful videostream that I see in VLC onto the disk for later encoding, I reckon the disks would be fast enough, or maybe something which would apply a light compression, enough that the disks can keep up, but not so much as to loose visible quality.

  I have tried FFMPEG as it seems capable of streaming a yuv4 stream down to the disk, but ofcause FFMPEG is unable to open the dshow device ( same error as this guy Ffmpeg streaming from capturing device Osprey 450e fails )

  Please recommend a capable and (preferably) software which can do this.

• ffmpeg converting mp4 to gif with color palette results in truncated video

  6 décembre 2019, par Tik0

  I want to generate a gif from my mp4 movie with ffmpeg (ffmpeg version 2.8.15-0ubuntu0.16.04.1) using a color palette. Everything works fine if I do not use a palette :

  $ ffmpeg -i in.mp4 -filter_complex "scale=160:-1" out.gif
  
  ...
  
  frame= 2003 fps=251 q=-0.0 Lsize=   21172kB time=00:01:20.12 bitrate=2164.7kbits/s    
  
  video:21155kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.077667%

  But using a palette like so results in Buffer queue overflow, dropping messages and a truncated video

  $ ffmpeg -i in.mp4 -filter_complex "[0:v] scale=160:-1, split [a][b];[a] palettegen [p];[b][p] paletteuse" out.gif
  
  ....
  
  [Parsed_paletteuse_3 @ 0xc56de0] [framesync @ 0xd1af08] Buffer queue overflow, dropping.
  
  Last message repeated 36 times
  
  [Parsed_paletteuse_3 @ 0xc56de0] [framesync @ 0xd1af08] Buffer queue overflow, dropping.
  
  Last message repeated 106 times
  
  ...
  
  [Parsed_palettegen_2 @ 0xc56d40] 255(+1) colors generated out of 1347441 colors; ratio=0.000189
  
  frame=   65 fps=5.4 q=-0.0 Lsize=    1036kB time=00:01:20.12 bitrate= 105.9kbits/s    
  
  video:1035kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.124664%

• Animated line chart with pandas, matplotlib and ffmpeg

  10 avril 2020, par Mark K

  In producing an animated line chart, I have below data and codes.

  



  But when the chart produced, it shows no line. What did I do wrong ?

  



  Thank you.

  



  import numpy as np
import pandas as pd
import seaborn as sns
import matplotlib
import matplotlib.pyplot as plt
import matplotlib.animation as animation

title = 'Heroin Overdoses'

data = {'Year' : ["1999","2000","2001","2002","2003","2004","2005","2006","2007","2008","2009","2010","2011","2012","2013","2014","2015","2016"], 
'Heroin Overdoses' : [280,443,413,486,475,148,197,170,448,103,137,160,483,356,352,300,466,278]}
overdose = pd.DataFrame(data)

Writer = animation.writers['ffmpeg']
writer = Writer(fps=20, metadata=dict(artist='Me'), bitrate=1800)

fig = plt.figure(figsize=(10,6))
plt.xlim(1999, 2016)
plt.ylim(np.min(overdose)[0], np.max(overdose)[0])
plt.xlabel('Year',fontsize=20)
plt.ylabel(title,fontsize=20)
plt.title('Heroin Overdoses per Year',fontsize=20)

def animate(i):
    data = overdose.iloc[:int(i+1)] #select data range
    p = sns.lineplot(x=data.index, y=data[title], data=data, color="r")
    p.tick_params(labelsize=17)
    plt.setp(p.lines,linewidth=7)

ani = matplotlib.animation.FuncAnimation(fig, animate, frames=17, repeat=True)

ani.save('C:\\folder\\line chart.mp4', writer=writer)