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• What parameter should use to create adaptive hls videos in different scale using ffmpeg and shaka packager for VOD streaming ?

  25 juin 2019, par Rahul

  I am trying to package HLS with shaka packager in a different scale from 144x256 to 1080x1920 for adaptive streaming using hevc, It is working fine, but Is there some more parameter required to put for good video quality and optimization.

  Below are the command I used :

  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=144:256 144_256_h265.mp4 -hide_banner
  
  
  
  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=360:640 360_640_h265.mp4 -hide_banner
  
  
  
  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=720:1280 720_1280_h265.mp4 -hide_banner
  
  
  
  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=1080:1920 1080_1920_h265.mp4 -hide_banner
  
  
  
  HLS Packaging Using shaka packager.
  
  packager-osx in=144_256_h265.mp4,stream=audio,output=hls/audio.mp4,playlist_name=audio.m3u8,hls_group_id=audio,hls_name=ENGLISH in=144_256_h265.mp4,stream=video,output=hls/h265_144p.mp4,playlist_name=h265_144p.m3u8,iframe_playlist_name=h265_144p_iframe.m3u8 in=360_640_h265.mp4,stream=video,output=hls/h265_360p.mp4,playlist_name=h265_360p.m3u8,iframe_playlist_name=h265_360p_iframe.m3u8 in=720_1280_h265.mp4,stream=video,output=hls/h265_720p.mp4,playlist_name=h265_720p.m3u8,iframe_playlist_name=h265_720p_iframe.m3u8  in=1080_1920_h265.mp4,stream=video,output=hls/h265_1080p.mp4,playlist_name=h265_1080p.m3u8,iframe_playlist_name=h265_1080p_iframe.m3u8 --hls_master_playlist_output hls/h265_master.m3u8

• Learn Multimedia Programming By Writing A JPEG Decoder

  6 janvier 2011, par Multimedia Mike — Programming

  For those of you who hack on multimedia tech, how did you get started ? Did you begin by studying the mathematical underpinnings of multimedia codec algorithms ? Or did you find a practical problem and jump right in by writing code ? (Personally, I was always more of a nuts & bolts hacker than a math guy.) I ask because I occasionally get emails from aspiring multimedia hackers who want to know where to begin. Invariably, they want to go the math-first route. I heavily discourage this approach.

  I have a crazy idea for anyone who wants a crash course on multimedia hacking : write a JPEG decoder. In doing so, you will be exposed to a lot of key domain concepts such as bitstream parsing, Huffman decoding, dequantization, zigzagging, the dreaded (inverse) discrete cosine transform, YUV vs. RGB colorspaces, macroblock organization, delta coding, and run length coding.

  Sure, JPEG decoding is a solved problem. But that’s hardly the point. Why would you enter an unfamiliar field and hope to come up to speed on the basics by leaping straight into the domain’s unsolved problems ? If you are successful in this exercise, no one will ever use the fruits of your labor, but that doesn’t really matter.

  So, do you want to learn multimedia hacking quickly ? Then grab a JPEG file (maybe create a few contrived ones that are small, have friendly dimensions, and feature predictable patterns), grab a good JPEG reference, and implement the decoding algorithm in the language and platform of your choice.

  On the matter of the reference, my personal favorite reference has always been A note about the JPEG decoding algorithm by Cristi Cuturicu. The English grammar is a bit dodgy but overall, it might be the best reference you’ll find on the matter— as simple as it needs to be, but no simpler.

  Good luck !

• Mirrored Arabic Letters using TextClip Moviepy

  4 août 2020, par Sam

  I am trying to render the video which contains arabic letters. let's use مرحبا for the example. After video rendered the result is mirrored.

  


  background = mp.ColorClip(mobile_size, (255, 255, 255), duration=0.5) #float(audiolength.info.length)
text1 = mp.TextClip(english, fontsize=45, color=fcolor, font=Font, size= (mobile_size[0], 185), method = 'caption', align="south").set_duration(0.5) #float(audiolength.info.length)
text2 = mp.TextClip(formatChineseSentences(translated).encode("utf-8"), fontsize=45, color=fcolor2, font=Font, size= (mobile_size[0], 185), method = 'caption', align="north").set_duration(0.5) #float(audiolength.info.length)

clip1 = mp.CompositeVideoClip([background, text1.set_position(('center', "top")), text2.set_position(('center', "bottom"))])


  


  Expected Behavior

  


  

  


  Actual Behavior

  


  

  


  Steps to Reproduce the Problem

  


  Rendering TextClip with Arabic Characters. For this case we can use مرحبا.

  


  Specifications

  


  Python Version : Python 3.8.5
Moviepy Version : 1.0.3
Platform Name : Mac OS Catalina
Platform Version : 10.15.6