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• Concatenating videos Audio/Video out of sync : Non-monotonous TDS output

  6 août 2020, par invider

  I am trying to add two videos using ffmpeg and the output video/audio is out of sync (and fast forwarded). Goal is to put intro.mp4 before the original file clip.flv

  



  My approach is to

  



  

  1. Change the format of clip.flv to clip.mp4

  


  



  ffmpeg -i clip.flv -q 0 -c copy clip.mp4


  



  

  2. Concat intro.mp4 with clip.mp4

  


  



  ffmpeg -f concat -safe 0 -i filesToJoin.txt -c copy combinedvideo.mp4


  



  I see this in output log for command#2

  



  [mp4 @ 0x3ebcd60] Non-monotonous DTS in output stream 0:0; previous: 392311, current: 391925; changing to 392312. This may result in incorrect timestamps in the output file.
frame= 1566 fps=0.0 q=-1.0 Lsize=    8711kB time=00:00:48.86 bitrate=1460.2kbits/s speed= 272x    
video:7363kB audio:1294kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.619341%


  



  ---

  



  Files Metadata

  



  Original source file clip.flv metadata

  



    Metadata:
    encoder         : Lavf57.83.100
  Duration: 00:00:40.09, start: 0.010000, bitrate: 1632 kb/s
    Stream #0:0: Video: h264 (High), yuv420p(progressive), 1280x720, 1500 kb/s, 30 fps, 30 tbr, 1k tbn, 60 tbc
    Stream #0:1: Audio: aac (LC), 44100 Hz, stereo, fltp, 160 kb/s


  



  Intermediary file intro.mp4 metadata

  



    Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42mp41
    creation_time   : 2020-06-02T10:36:51.000000Z
  Duration: 00:00:13.21, start: 0.000000, bitrate: 484 kb/s
    Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 1280x720 [SAR 1:1 DAR 16:9], 130 kb/s, 30 fps, 30 tbr, 30k tbn, 60k tbc (default)
    Metadata:
      creation_time   : 2020-06-02T10:36:51.000000Z
      handler_name    : Alias Data Handler
      encoder         : AVC Coding
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 317 kb/s (default)
    Metadata:
      creation_time   : 2020-06-02T10:36:52.000000Z
      handler_name    : Alias Data Handler


  



  File clip.mp4 metadata

  



      Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.83.100
  Duration: 00:00:40.01, start: 0.000000, bitrate: 1635 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720, 1500 kb/s, 30 fps, 30 tbr, 16k tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 160 kb/s (default)
    Metadata:
      handler_name    : SoundHandler


  



  ---

  



  Things I have tried

  



  

  • As you'll see that the both videos have same frame rate but different timescale, I have tried changing the timescale of one of the video to match the other before combining the video but with no luck. For timescale change I used this command

  


  



  ffmpeg -i clip.mp4 -video_track_timescale 30000 clip_ts30000.mp4

  



  

  • I have seen the similar questions on SO, no luck

  


  


• ffmpeg change the order of the output

  14 juin 2020, par roko

  i try to change the order of the output of 3 inputs (2 audio + 1 video)
this is my command :

  



  /usr/bin/ffmpeg -async 1 \
-f pulse -i alsa_output.pci-0000_00_1b.0.analog-stereo.monitor \
-f pulse -i alsa_input.pci-0000_00_1b.0.analog-stereo \
-f x11grab -video_size 1920x1080 -framerate 8 -i :0.0 \
-filter_complex amix=inputs=2 \
-c:a aac -b:a 128k \
-c:v h264_nvenc -b:v 1500k -maxrate 1500k -minrate 1500k \
-override_ffserver -g 16 http://10.100.102.109:8090/feed1.ffm


  



  this command works but, the first output is audio , therefore my third app cant view this output 
this is my output :

  



  Stream mapping:
  Stream #0:0 (pcm_s16le) -> amix:input0 (graph 0)
  Stream #1:0 (pcm_s16le) -> amix:input1 (graph 0)
  amix (graph 0) -> Stream #0:0 (aac)
  Stream #2:0 -> #0:1 (rawvideo (native) -> h264 (h264_nvenc))
Press [q] to stop, [?] for help
-async is forwarded to lavfi similarly to -af aresample=async=1:min_hard_comp=0.100000:first_pts=0.
    Last message repeated 1 times
Output #0, ffm, to 'http://10.100.102.109:8090/feed1.ffm':
  Metadata:
    creation_time   : now
    encoder         : Lavf57.83.100
    Stream #0:0: Audio: aac (LC), 48000 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      encoder         : Lavc57.107.100 aac
    Stream #0:1: Video: h264 (h264_nvenc) (Main), bgr0, 1920x1080, q=-1--1, 1500 kb/s, 8 fps, 1000k tbn, 8 tbc
    Metadata:
      encoder         : Lavc57.107.100 h264_nvenc
    Side data:
      cpb: bitrate max/min/avg: 1500000/0/1500000 buffer size: 3000000 vbv_delay: -1


  



  ****how can i replace the output that the video will be first ?****

  



  (when i do this command with 1 audio and 1 video inputs, the output is fine, the video is first , and the third part App can view it)

  



  i spent a lot of hours on it please help me.

  



  tnx a lot ...

  


• How to visualize matplotlib animation in Jupyter notebook

  23 avril 2020, par anonymous13

  I am trying to create a racing bar chart similar to the one in the link (https://towardsdatascience.com/bar-chart-race-in-python-with-matplotlib-8e687a5c8a41). 
However I am unable to see the animation in my Jupyter notebook

  



  code

  



  import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.ticker as ticker
import matplotlib.animation as animation
from IPython.display import HTML

df = pd.read_csv('https://gist.githubusercontent.com/johnburnmurdoch/4199dbe55095c3e13de8d5b2e5e5307a/raw/fa018b25c24b7b5f47fd0568937ff6c04e384786/city_populations', 
                 usecols=['name', 'group', 'year', 'value'])

current_year = 2018
dff = (df[df['year'].eq(current_year)]
       .sort_values(by='value', ascending=True)
       .head(10))

colors = dict(zip(
    ['India', 'Europe', 'Asia', 'Latin America',
     'Middle East', 'North America', 'Africa'],
    ['#adb0ff', '#ffb3ff', '#90d595', '#e48381',
     '#aafbff', '#f7bb5f', '#eafb50']
))
group_lk = df.set_index('name')['group'].to_dict()


fig, ax = plt.subplots(figsize=(15, 8))
def draw_barchart(year):
    dff = df[df['year'].eq(year)].sort_values(by='value', ascending=True).tail(10)
    ax.clear()
    ax.barh(dff['name'], dff['value'], color=[colors[group_lk[x]] for x in dff['name']])
    dx = dff['value'].max() / 200
    for i, (value, name) in enumerate(zip(dff['value'], dff['name'])):
        ax.text(value-dx, i,     name,           size=14, weight=600, ha='right', va='bottom')
        ax.text(value-dx, i-.25, group_lk[name], size=10, color='#444444', ha='right', va='baseline')
        ax.text(value+dx, i,     f'{value:,.0f}',  size=14, ha='left',  va='center')
    # ... polished styles
    ax.text(1, 0.4, year, transform=ax.transAxes, color='#777777', size=46, ha='right', weight=800)
    ax.text(0, 1.06, 'Population (thousands)', transform=ax.transAxes, size=12, color='#777777')
    ax.xaxis.set_major_formatter(ticker.StrMethodFormatter('{x:,.0f}'))
    ax.xaxis.set_ticks_position('top')
    ax.tick_params(axis='x', colors='#777777', labelsize=12)
    ax.set_yticks([])
    ax.margins(0, 0.01)
    ax.grid(which='major', axis='x', linestyle='-')
    ax.set_axisbelow(True)
    ax.text(0, 1.12, 'The most populous cities in the world from 1500 to 2018',
            transform=ax.transAxes, size=24, weight=600, ha='left')
    ax.text(1, 0, 'by @pratapvardhan; credit @jburnmurdoch', transform=ax.transAxes, ha='right',
            color='#777777', bbox=dict(facecolor='white', alpha=0.8, edgecolor='white'))
    plt.box(False)

draw_barchart(2018)

import matplotlib.animation as animation
from IPython.display import HTML
fig, ax = plt.subplots(figsize=(15, 8))
animator = animation.FuncAnimation(fig, draw_barchart, frames=range(1968, 2019))
HTML(animator.to_jshtml()) 



  



  Below is what I tried using and the errors

  



  HTML(animator.to_jshtml())  <-- Static output with buttons unable to visualize animation
plt.rcParams["animation.html"] = "jshtml"  <- no error and output
HTML(animator.to_html5_video())  <---Requested MovieWriter (ffmpeg) not available 



  



  Note I have FFmpeg installed in my system.
Can you help me with the issue