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• Concatenating *.mkv files using ffmpeg

  25 mars 2020, par Daniel F

  I’ve just about lost my mind on this, I’m sure I’m missing something simple.

  I have two *.mkv files generated by OBS. Even better, I’ve just copied one file twice, so I am sure I have the same bitrate, fps, tbn, whatever.

  then I do :

  ffmepg -i "concat:file1.mkv|file1_copy.mkv" -c copy test.mkv

  It runs and my screen fills with yellow messages :

      ffmpeg -i "concat:file1.mkv|file1_copy.mkv" -c copy test.mkv
  
  ffmpeg version 4.2 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with gcc 9.1.1 (GCC) 20190807
  
    configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt
  
    libavutil      56. 31.100 / 56. 31.100
  
    libavcodec     58. 54.100 / 58. 54.100
  
    libavformat    58. 29.100 / 58. 29.100
  
    libavdevice    58.  8.100 / 58.  8.100
  
    libavfilter     7. 57.100 /  7. 57.100
  
    libswscale      5.  5.100 /  5.  5.100
  
    libswresample   3.  5.100 /  3.  5.100
  
    libpostproc    55.  5.100 / 55.  5.100
  
  Input #0, matroska,webm, from 'concat:file1.mkv|file1_copy.mkv':
  
    Metadata:
  
      ENCODER         : Lavf58.20.100
  
    Duration: 00:00:09.15, start: 0.000000, bitrate: 2006 kb/s
  
      Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 60 fps, 60 tbr, 1k tbn, 120 tbc (default)
  
      Metadata:
  
        DURATION        : 00:00:09.150000000
  
      Stream #0:1: Audio: aac (LC), 44100 Hz, stereo, fltp (default)
  
      Metadata:
  
        title           : simple_aac_recording
  
        DURATION        : 00:00:09.102000000
  
  Output #0, matroska, to 'test.mkv':
  
    Metadata:
  
      encoder         : Lavf58.29.100
  
      Stream #0:0: Video: h264 (High) (H264 / 0x34363248), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 60 fps, 60 tbr, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        DURATION        : 00:00:09.150000000
  
      Stream #0:1: Audio: aac (LC) ([255][0][0][0] / 0x00FF), 44100 Hz, stereo, fltp (default)
  
      Metadata:
  
        title           : simple_aac_recording
  
        DURATION        : 00:00:09.102000000
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  [matroska,webm @ 00000156ce7f14c0] File extends beyond end of segment.
  
  [matroska @ 00000156cef62040] Non-monotonous DTS in output stream 0:0; previous: 9100, current: 0; changing to 9100. This may result in incorrect timestamps in the output file.
  
  [matroska @ 00000156cef62040] Non-monotonous DTS in output stream 0:0; previous: 9100, current: 67; changing to 9100. This may result in incorrect timestamps in the output file.
  
  [matroska @ 00000156cef62040] Non-monotonous DTS in output stream 0:0; previous: 9100, current: 33; changing to 9100. This may result in incorrect timestamps in the output file.
  
  [matroska @ 00000156cef62040] Non-monotonous DTS in output stream 0:1; previous: 9102, current: 0; changing to 9102. This may result in incorrect timestamps in the output file.
  
  [matroska @ 00000156cef62040] Non-monotonous DTS in output stream 0:0; previous: 9100, current: 17; changing to 9100. This may result in incorrect timestamps in the output file.
  
  
  
  ############## thousands of the above lines here #####################
  
  
  
  frame= 1098 fps=0.0 q=-1.0 Lsize=    2241kB time=00:00:09.11 bitrate=2013.0kbits/s speed=24.9x
  
  video:2068kB audio:159kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.607770%

  When opened, the timestamps only go to the end of the first segment, even though the video continues afterwards. Normally this would be fine, but I’m recording instructional videos and it would be nice for users to be able to skip around them. This occurs even if I re-encode the videos (which I shouldn’t need, since they are identical) or re-encode the output.

  Everything I have read online says :

  • re-encode*into .mkv to fix this, since .mkv has a fixed tbn - it’s already .mkv

  • the problem is different bitrates/tbs/fps/whatever - for now, they’re the same video twice

  • use -fflags +genpts, -use_wallclock_as_timestamps 1, vsync 0 -enc_time_base -1 - none of these do anything as far as I can tell, either before -i or after -c copy

  I’ve run out of ideas. What am I doing wrong.

• 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)


  


• avformat/movenc : use enum values directly for colr atom

  31 mars 2020, par Michael Bradshaw

  avformat/movenc : use enum values directly for colr atom
  The switch cases were missing :
    - Primaries : bt470m, film, smpte428, and ebu3213.
  
    - TRCs : gamma22, gamma28, linear, log, log_sqrt, iec61966_2_4, bt1361,
  
      iec61966_2_1, bt2020_10bit, and bt2020_12bit.
  
    - Space : rgb, fcc, ycgco, bt2020_cl, smpte2085, chroma-derived-nc,
  
      chroma-derived-c, and ictcp.
  They also annoyingly remapped the following (which are functionally
  
  equivalent but can be treated differently by clients) :
    - smpte240m primaries to smpte170m.
  
    - smpte170m TRC to bt709.
  
    - bt470bg color space to smpte170m.
  The enum values in FFmpeg are the same values as ITU-T H.273 and
  
  ISO/IEC 23001-8 so we can just use them directly, which is both simpler
  
  and preserves the user intent.
  Signed-off-by : Michael Bradshaw <mjbshaw@google.com>
  

  • [DH] libavformat/movenc.c