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• Youtube-DL file download live progress

  7 février 2015, par roshkattu

  I am using the YoutubeDL library in a project. My environment is based on WINDOWS with XAMPP as the webserver boundle (apache,php,mysql,etc). I am using the youtube-dl.exe file to download the video and then use ffmpeg.exe to convert the video to an MP3 audio file.

  At the moment, I have an issue related to programming : I want to show live a progressbar while the video is downloaded with the youtube-dl.exe file. This exe creates a log file, that is updated while the video is downloaded. So my approach on this was to create a PHP file, that opens, parses the log file and get’s the progress percent, and sends it as a json encoded value to an AJAX function that is called every 100MS. Indeed, if the video is too large, there will be a very high ammount of data while polling the PHP file to get the progress state. And sometimes, the browser either crashes or freezes because of this ajax polling.

  My question is : is there any better approach to do this with PHP/AJAX ? Rathar than poll the file every 100MS, or 50MS ?

• Where can I get 16-bit video sequences ? [on hold]

  9 mai 2017, par govind

  I understand that I can create 16-bit videos from 8-bit ones, but I want to work on actual 16-bit data (for a class project) and not just the bit-shifted pixel values. I just want to extract and work on the 16-bit Luma component from the video.

  https://media.xiph.org/ has 16-bit raw contents but the file size is 500GB. I would like to limit my downloads to 1-2 GB.
  The footnote at https://media.xiph.org/video/derf/ says "These were converted from 16-bit linear RGB to Y’CbCr", can I get the source from which these conversion took place.

  I could create my own content with some custom pattern but that’s not an option since I want to work on natural-looking imagery.

  I do understand that regular monitors can only display 8-bit. I also understand that it’s not a typical StackOverflow question, but I have already spent 2 hours online searching for it. Any links will be appreciated. Thanks in advance.

• Generating Gif from Mp4 directly - ffmpeg

  20 janvier 2016, par senty

  I am trying to generate a gif from an mp4 video file. I want to scale it and crop it while generating.

  I achieved that (cropping & scaling) from mp4 to mp4 with the below line , (so I can extract pngs with ffmpeg and use Imagick to make animated gif), but I believe there is a better way of achieving purely with ffmpeg.

  ffmpeg -i in.mp4 -filter:v "scale=300:ih*300/iw, crop=200:500:50:80" -c:a copy out.mp4

  My question is how to achieve the same this code is doing, but for directly generating gif from mp4.

  ---

  Then I started tweaking with mp4 to gif conversion, but when palette comes in, I couldn’t fully understand what’s going on.

  I found this answer and I made it work, however I couldn’t understand how to adapt scaling & cropping.

  $ ffmpeg -y -ss 30 -t 3 -i in.mp4 \
-vf fps=10,scale=320:-1:flags=lanczos,palettegen palette.png

  $ ffmpeg -ss 30 -t 3 -i in.flv -i palette.png -filter_complex \ "fps=10,scale=320:-1:flags=lanczos[x];[x][1:v]paletteuse" out.gif

  I partially understand what this bit does -y -ss 30 -t 3 -i in.mp4 (getting the first 30 seconds and generating a 3 second gif out of it). But for the next lines, I am completely lost what it is actually doing.

  It’d be amazing if someone can explain what each command does, or refer a link explaining this topic.