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• Python ffmpeg subprocess makes unplayable file, but is right size, and just hangs

  8 juin 2021, par nadermx

  I currently have this subprocess calling ffmpeg.

  


  print("Starting alphamerge")
cmd = "ffmpeg -y -nostats -loglevel 0 -i %s -i %s -filter_complex '[1][0]scale2ref[mask][main];[main][mask]alphamerge' -c:v qtrle %s" % (
            file_path, temp_file, output)
process = sp.Popen(cmd, shell=True, stdout=sp.PIPE, stderr=sp.PIPE)
stdout, stderr = process.communicate()
print('after call')

if stderr:
   return "ERROR: %s" % stderr.decode("utf-8")
print("Process finished")




  


  But the process ends up making a file over 2 gigs, unplayable, and just hangs. It never prints "Process finished", "after call", or an error, it just hangs.

  


  Am I calling subprocess with ffmpeg wrong ?

  


• ffmpeg - concatenate several videos with xfade transition

  8 mai 2021, par ilim

  I have N videos, and I'm using ffmpeg to concatenate them with xfade transitions between them. The video files are named as positive integers representing their order in the concatenated output, and none of them have any audio. In fact, each file just includes a different image with no animation that stays on screen all through that video's duration.

  


  I'm using a simple command I found in a response to an existing question to concatenate the first 2 videos :

  


  ffmpeg -i 1.mp4 -i 2.mp4 -y
       -filter_complex "xfade=transition=fade:offset=3.5:duration=0.5"
       1-2.mp4


  


  I planned to employ that same command for all the videos, each time appending a single video to the cumulative one produced so far, and producing an intermediary output to be used later.

  


  Specifically, I first concatenated files 1.mp4 and 2.mp4, and recorded the result into 1-2.mp4, which was produced correctly. Videos had the respective duration of 4 and 8 seconds, and the resulting 1-2.mp4 was 12 seconds long, with the transition occurring when it should.

  


  The problem started when I tried concatenating 1-2.mp4 and 3.mp4. I used the following command to generate a concatenation of videos [1-3].

  


  ffmpeg -i 1-2.mp4 -i 3.mp4 -y
       -filter_complex "xfade=transition=fade:offset=11.5:duration=0.5"
       1-3.mp4


  


  The video produced seems to be an exact copy of 1-2.mp4, and contents of 3.mp4 are not present at all in the resulting 1-3.mp4. Video file 3.mp4 was 3 seconds long, but the resulting 1-3.mp4 was 12 seconds long, just like 1-2.mp4 was.

  


  Apart from the input and output file names, both commands are the same. I was suspicious of having set the offset parameter of the transition incorrectly, but the first 2 files were merged successfully.

  


  I am at a loss as to what I'm doing incorrectly here. Is there a particular caveat of the xfade filter that gets problematic when used among 2 files with one of them already having that filter ?

  


  Any suggestions as to how I may debug or fix this behavior ? I'd welcome any alternative means of concatenating these (i.e., with some transition effects) in a simple fashion as well.

  


  I'm planning to use these commands in a Python script, so I'd appreciate any alternative solution not involving any gigantic commands or parameters.

  


  Just to be thorough, I should mention that I have ffmpeg version 4.3.1 installed via snap.

  


• How to setup a video chunker or FFMPEG to bypass Cloudflare ?

  20 avril 2021, par RustyGates

  In full transparency, I am a noob so please forgive my lack of appropriate lingo as I am just barely starting to learn the languages of web development. Hope you don't have to try and decipher too much of what I'm trying to say.

  


  So in an attempt to put this as simply as possible.

  


  I have a PHP Script CMS that I have been doing some extensive custom work to. As mentioned, I am still learning for the most part and while my front end skills are getting very well polished, I'm still completely lose mostly when it comes to back end endeavors. And for reference, the CMS I am using is Wowonder from Codecanyon. It's essentially just a social media cms, like Facebook.

  


  I have this installed on my own dedicated server, have WHM/Cpanel, all that good stuff. I also have my website/domain setup through Cloudflare properly. This is where the issue arises. Cloudflare limits uploads to 100 megabytes. Some of the users on my website will be uploading videos and media much bigger than 100 megabytes. (Up to 10 gigabytes in some cases). I have researched the issue long and hard and it would seem to me the obvious was to resolve the problem would be to use a video chunker (and/or something like FFMPEG ? But not sure if FFMPEG Is capable of it. Am just assuming).

  


  I understand the basic, general idea of what chunkers do and have found some seemingly good options. Will post a couple below just as an example but not necessarily options I was considering.

  


  [https://github.com/blueimp/jQuery-File-Upload][1]

  


  [https://github.com/c0decracker/video-splitter][2]

  


  [https://github.com/appijumbo/video-chunk][3]

  


  So again, I understand the basic idea, it would chunk up the video while uploading (somewhere beneath the 100 megabyte maximum) to bypass Cloudflare's limit, and then stitch the video back together so it's in it's in it's complete form again. However, with a website that has many users uploading, I have not the slightest idea what the best solution is, or if this is the best solution at all, and if it is, how to implement it properly.

  


  I have also installed FFMPEG on my server and did so successfully but not sure how to implement that properly either now how to tell it that it should automatically encode any videos uploaded to the website by any users and so on, nor sure if it's possible to do chunking with it although it seemingly is ?

  


  Any advice is on the topic is much appreciated and I would be much obliged. Thanks in advance.