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• ffmpeg continous file stream or live stream

  17 novembre 2019, par shrw

  I work in a news channel. and the use case is little common.
  Where we have ads lined up. Let’s say 1000 ads in the entire day. ads are usually gif files overlay of 100 pixels X 500 pixels and usually less than 10 seconds.
  then we need to either play mp4 files or stream live content.
  What i really want is to :

  1. if we have 30 mp4 files to play in the entire day and 1000 gif overlay ads.
  2. Is it possible to switch(with the help of any coding languale like node.js or linux commands)
     streams from file to live stream.

• 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

  


• avformat/matroskaenc : Don't override samplerate for CodecDelay

  29 août 2022, par Andreas Rheinhardt

  avformat/matroskaenc : Don't override samplerate for CodecDelay
  Opus can be decoded to multiple samplerates (namely 48kHz, 24KHz,
  
  16Khz, 12 KHz and 8Khz) ; libopus as well as our encoder wrapper
  
  support these sample rates. The OpusHead contains a field for
  
  this original samplerate. Yet the pre-skip (and the granule-position
  
  in the Ogg-Opus mapping in general) are always in the 48KHz clock,
  
  irrespective of the original sample rate.
  Before commit c3c22bee6362737cf290929b7f31df9fb88da983, our libopus
  
  encoder was buggy : It did not account for the fact that the pre-skip
  
  field is always according to a 48kHz clock and wrote a too small
  
  value in case one uses the encoder with a sample rate other than 48kHz ;
  
  this discrepancy between CodecDelay and OpusHead led to Firefox
  
  rejecting such streams.
  In order to account for that, said commit made the muxer always use
  
  48kHz instead of the actual sample rate to convert the initial_padding
  
  (in samples in the stream's sample rate) to ns. This meant that both
  
  fields are now off by the same factor, so Firefox was happy.
  Then commit f4bdeddc3cab807e43e0450744dfe9a45661e1d7 fixed the issue
  
  in libopusenc ; so the OpusHead is correct, but the CodecDelay is
  
  still off*. This commit fixes this by effectively reverting
  
  c3c22bee6362737cf290929b7f31df9fb88da983.
  * : Firefox seems to no longer abort when CodecDelay and OpusHead
  
  are off.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavformat/matroskaenc.c
  • [DH] libavformat/version.h