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• Multiply the video with a scalar with FFMPEG

  16 novembre 2020, par Terpsiphone

  I have to adjust a video which was too dark. In openCV, I simply used Img.Mul() to multiply each of the RGB band with a same scalar and got good result.

  


  Could one do the equivalent operation with FFMPEG ? I tried eq with contrast and brightness, but it was not quite the same thing.

  


  Edit : thanks to a clue in @VC.One's answer below I was able to emulate Img.Mul() with :

  


  ffmpeg -i input.file -vf colorlevels=rimax=0.5:gimax=0.5:bimax=0.5 -c:a copy output.file


  


• Evolution of Multimedia Fiefdoms

  1er octobre 2014, par Multimedia Mike — General

  I want to examine how multimedia fiefdoms have risen and fallen through the years.

  
  
  

  Back in the day, the multimedia fiefdoms were built around the formats put forth by competing companies : there was Microsoft/WMV, Apple/MOV, and Real/RM as the big contenders. On2 always wanted to be a player in this arena but could never quite catch a break. A few brave contenders held the line for open source and also for the power users who desired one application that could handle everything (my original motivation for wanting to get into multimedia hacking).

  The computer desktop was the battleground for internet-based media stream. Whatever happened to those days ? Actually, if memory serves, Flash-based video streaming stepped on all of them.

  Over the last 6-7 years, the battleground has expanded to cover mobile devices, where Flash’s impact has… lessened. During this time, multimedia technology pretty well standardized on a particular stack, namely, the MPEG (MP4/H.264/AAC) stack.

  The belligerents in this war tried for years to effectively penetrate new territory, namely, the living room where the television lived. This had been slowgoing for years due to various user interface and content issues, but steadily improved.

  Last April, Amazon announced their entry into the set-top box market with the Fire TV. That was when it suddenly crystallized for me that the multimedia ecosystem has radically shifted. Now, the multimedia fiefdoms revolve around access to content via streaming services.

  Off the top of my head, here are some of the fiefdoms these days (fiefdoms I have experience using) :

  • Netflix (subscription streaming)
  • Amazon (subscription, rental, and purchased streaming)
  • Hulu Plus (subscription streaming)
  • Apple (rental and purchased media)

  I checked some results on Can I Stream.It ? (which I refer to often) and found a bunch more streaming fiefdoms such as Google (both Play and YouTube, which are separate services), Sony, Xbox 360, Crackle, Redbox Instant, Vudu, Target Ticket, Epix, Sony, SnagFilms, and XFINITY StreamPix. And surely, these are probably just services available in the United States ; I know other geographical regions have their own fiefdoms.

  What happened ?

  When I got into multimedia hacking, there were all these disparate, competing ecosystems. As a consumer, I didn’t care where the media came from, I just wanted to play it. That’s what inspired me to work on open source multimedia projects. Now I realize that I have the same problem 10-15 years later : there are multiple competing ecosystems. I might subscribe to fiefdoms X and Y, but am frustrated to learn that something I’d like to watch is only available through fiefdom Z. Very few of these fiefdoms can be penetrated using open source technology.

  I’m not really sure about the point about this whole post. Multimedia technology seems really standardized these days. But that’s probably just my perspective because I have spent way too long focusing on a few areas of multimedia technology such as audio and video coding. It’s interesting that all these services probably leverage the same limited number of codecs. Their differentiation comes from the catalog of content that each is able to license for streaming. There are different problems to solve in the multimedia arena now.

• How to create a video thumbnail without ffmpeg or HTML5 video canvas ? [duplicate]

  14 mai 2014, par user3631926

  This question already has an answer here :

  • How to generate thumbnails on Amazon S3 ?
    
    2 answers
    

  I need to create a thumbnail from a video, I have tried the below options but they didn’t work for my case. I am using S3 and CloudFront.

  1. ffmpeg is not supported via my hosting because I am using a shared hosting and I need to upgrade to VPS or dedicated server if I want to use ffmpeg.

  2. I tried taking a screenshot from the video using HTML5 drawImage and toDataURL functions, but it is throwing SecurityError because my video file is located on Amazon CloudFront and my code is hosted somewhere else.

  Is there any other option or a workaround to the second option ? I don’t want to upgrade my server for just the thumbnail issue.