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• 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)


  


• FFmpeg : A few errors including invalid frame size and incomplete frame

  8 février 2019, par Abs

  I use this ffmpeg command to take clips from a large VOB files that is on a DVD :

  ffmpeg.exe -i E:\VTS_02_2.vob -ss 00:00:57 -t 00:16:15 vids\VTS_02_2.vob

  It worked first for a VOB file but then I got these errors :

  c:\ffmpeg>ffmpeg.exe -i E:\VTS_02_2.vob -ss 00:00:57 -t 00:16:15 vids\VTS_02_2.vob
  
  FFmpeg version SVN-r15625, Copyright (c) 2000-2008 Fabrice Bellard, et al.
  
    configuration: --enable-memalign-hack --enable-postproc --enable-swscale --enable-g
  
  l --enable-libfaac --enable-libfaad --enable-libgsm --enable-libmp3lame --enable-libv
  
  rbis --enable-libtheora --enable-libx264 --enable-libxvid --disable-ffserver --disabl
  
  -vhook --enable-avisynth --enable-pthreads
  
    libavutil     49.12. 0 / 49.12. 0
  
    libavcodec    52. 0. 0 / 52. 0. 0
  
    libavformat   52.22. 1 / 52.22. 1
  
    libavdevice   52. 1. 0 / 52. 1. 0
  
    libswscale     0. 6. 1 /  0. 6. 1
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
    built on Oct 16 2008 05:40:02, gcc: 4.2.4 (TDM-1 for MinGW)
  
  Input #0, mpeg, from 'E:\VTS_02_2.vob':
  
    Duration: 00:17:11.61, start: 1031.828511, bitrate: 8326 kb/s
  
      Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576 [PAR 16:15 DAR 4:3], 9640
  
  kb/s, 25.00 tb(r)
  
      Stream #0.1[0x80]: Audio: ac3, 48000 Hz, stereo, s16, 192 kb/s
  
  File 'vids\VTS_02_2.vob' already exists. Overwrite ? [y/N] y
  
  Output #0, svcd, to 'vids\VTS_02_2.vob':
  
      Stream #0.0: Video: mpeg2video, yuv420p, 720x576 [PAR 16:15 DAR 4:3], q=2-31, 200
  
  kb/s, 25.00 tb(c)
  
      Stream #0.1: Audio: mp2, 48000 Hz, stereo, s16, 64 kb/s
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
    Stream #0.1 -> #0.1
  
  Press [q] to stop encoding
  
  [ac3 @ 026D3990]frame sync error
  
  Error while decoding stream #0.1
  
  frame=    0 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  [mpeg2video @ 0141B780]ac-tex damaged at 40 2
  
  [mpeg2video @ 0141B780]invalid mb type in B Frame at 3 12
  
  [mpeg2video @ 0141B780]00 motion_type at 15 16
  
  [mpeg2video @ 0141B780]mb incr damaged
  
  [mpeg2video @ 0141B780]00 motion_type at 2 21
  
  [mpeg2video @ 0141B780]00 motion_type at 44 22
  
  [mpeg2video @ 0141B780]ac-tex damaged at 43 24
  
  [mpeg2video @ 0141B780]Warning MVs not available
  
  [mpeg2video @ 0141B780]concealing 765 DC, 765 AC, 765 MV errors
  
  frame=    0 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  frame=    0 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  frame=    0 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  frame=    0 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  [mpeg2video @ 0141B780]ac-tex damaged at 5 9
  
  [mpeg2video @ 0141B780]00 motion_type at 21 13
  
  [mpeg2video @ 0141B780]ac-tex damaged at 1 20
  
  [mpeg2video @ 0141B780]mb incr damaged
  
  [mpeg2video @ 0141B780]00 motion_type at 30 30
  
  [mpeg2video @ 0141B780]Warning MVs not available
  
  [mpeg2video @ 0141B780]concealing 450 DC, 450 AC, 450 MV errors
  
  [ac3 @ 026D3990]frame CRC mismatch
  
  [ac3 @ 026D3990]incomplete frame
  
  [ac3 @ 026D3990]invalid frame size
  
  frame=    0 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  [mpeg2video @ 0141B780]00 motion_type at 38 15
  
  [mpeg2video @ 0141B780]00 motion_type at 30 34
  
  [mpeg2video @ 0141B780]Warning MVs not available
  
  [mpeg2video @ 0141B780]concealing 254 DC, 254 AC, 254 MV errors
  
  frame=    0 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  frame=    0 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  [mpeg2video @ 0141B780]ac-tex damaged at 7 6
  
  [mpeg2video @ 0141B780]concealing 1350 DC, 1350 AC, 1350 MV errors
  
  frame=    0 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  [ac3 @ 026D3990]incomplete frame
  
  [ac3 @ 026D3990]invalid frame size
  
  frame=    0 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  frame=    0 fps=  0 q=0.0 Lsize=       0kB time=10000000000.00 bitrate=   0.0kbits/s
  
  
  
  video:0kB audio:0kB global headers:0kB muxing overhead -1.#IND00%

  Is there a way to force ffmpeg to just give me an output ?

• why type casting on non-pointer struct give syntax error

  1er avril 2020, par Sany Liew

  I am using Visual C++ express 2008 try to compile code similar to below :

  



  no problem

  



  {
  ...
  AVRational test = {1, 1000};
  ...
}


  



  but has problem when it is as below :

  



  {
  ...
  AVRational test = (AVRational){1, 1000};
  ...
}


  



  gave errors :

  



  1>..\..\..\projects\test\xyz.cpp(1139) : error C2059: syntax error : '{'
1>..\..\..\projects\test\xyz.cpp(1139) : error C2143: syntax error : missing   ';' before '{'
1>..\..\..\projects\test\xyz.cpp(1139) : error C2143: syntax error : missing ';' before '}'


  



  where AVRational (ffmpeg.org library) is defined as :

  



  typedef struct AVRational{
    int num; ///< numerator
    int den; ///< denominator
} AVRational;


  



  FFmpeg come with some pre-define value such as

  



  #define AV_TIME_BASE_Q (AVRational){1, AV_TIME_BASE}


  



  which is used as below

  



  av_rescale_q(seek_target, AV_TIME_BASE_Q, pFormatCtx->streams[stream_index]->time_base);


  



  will failed to compile on Visual C++ express 2008

  



  It seem like the same code will be compiled with no error/warning on gcc compiler. Why I get this error on VC++ ? Is it a C/C++ standard way to do casting on struct value ? Anyway I can avoid this error while still able to use the defined AV_TIME_BASE_Q ?