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• FFmpeg - How to get the timestamp of the frame of which a thumbnail was generated ?

  11 avril 2020, par user2851148

  I am using FFmpeg to extract a screenshot through the timestamp, but I get this timestamp manually by watching the video in VLC and looking for the exact moment of the thumbnail was generated, this process is very time consuming and I need to do it with 220 videos.

  



  All this in order to get a high resolution image of the thumbnail, I also have to mention that the thumbnail file does not have the timestamp in the metadata and in the title.

  



  Would there be any way for FFmpeg to give me the exact timestamp where the thumbnail was taken ?

  



  UPDATED

  



  After a couple of hours testing with FFmpeg commands I found the solution, it is not completely automatic but it works, then the command is :

  



  ffmpeg -ss 00:02:30 -i video.mp4 -t 00:00:40 -loop 1 -i thumbnail.jpg \
   -filter_complex "scale=480:270,hue=s=0,blend=difference:shortest=1, \
    blackframe=95:30,fps=fps=23" -f null -


  



  Options to modify :

  



  

  1. "video.mp4" replace for the video file (obviously).

  


  2. "thumbnail.jpg" replace for the thumbnail file.

  


  3. "-ss" and "-t" are the range of time where the thumbnail likely to be.


     

     • "-ss" time start 00:02:30 (2min with 30 sec)

     


     • "-t" time since start 00:00:40 (2min with 30sec + 40sec)

     


     • If you have no idea where probably is the thumbnail, you can delete this part, only it will take longer to find it.

     


  


  4. "480:270" replace for size of the thumbnail.

  


  5. "fps=23" change the 23 for the fps exact of the "video.mp4" file.

  


  



  And answer we have :

  



  [Parsed_blackframe_1] frame:3849 pblack:100 pts:160535 t:160.535000


  



  In this example, we can see that the command has given us the exact timestamp where the thumbnail was generated "160.535000" which is in seconds with microseconds.

  



  Now to extract the thumbnail in high resolution we could use the found timestamp, but consider that it would be more exact and precise to use the frame number, which in this case would be "frame:3849".

  



  Using this command, we obtain the exact image :

  



  ffmpeg -i video.mp4 -vf "select=gte(n\, 3849)" -vframes 1 high_resolution.png


  



  Well I hope this is helpful for someone who is looking for the original image of a thumbnail or in general who needs to know exactly the minute where it was taken.

  



  If someone in the future likes to make a script that can fully automate this process, I would be grateful :)

  


• 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.

  


• how to fix ffmpeg error 'frame crc mismatch'

  9 août 2013, par Sam

  I am trying to re-encode a video file using ffmpeg but every time I try to run it

  ffmpeg -i  -c:v libx264 -crf 25 -preset slow -c:a libfaac 

  it does the first five minutes or so of the video and then gives the following error and stops :

  frame CRC mismatch
  
  [matroska,webm @ 0x7ff609806600] Unknown entry 0x762F
  
  [matroska,webm @ 0x7ff609806600] Unknown entry 0x4B61
  
  [matroska,webm @ 0x7ff609806600] Unknown entry 0xA2
  
  [matroska,webm @ 0x7ff609806600] Unknown entry 0x7F38
  
  [matroska,webm @ 0x7ff609806600] Unknown entry 0x39E0B1
  
  frame= 7473 fps=8.3 q=30.0 size=   42488kB time=-577014:-32:-22.-77 bitrate=N/A 
  
  frame= 7473 fps=8.2 q=-1.0 Lsize=   43099kB time=00:05:12.06 bitrate=1131.4kbits/s    
  
  video:35549kB audio:7338kB subtitle:0 global headers:0kB muxing overhead 0.494802%
  
  [libx264 @ 0x7ff609826c00] frame I:70    Avg QP:21.35  size: 41968
  
  [libx264 @ 0x7ff609826c00] frame P:2000  Avg QP:24.37  size:  9139
  
  [libx264 @ 0x7ff609826c00] frame B:5403  Avg QP:26.21  size:  2811
  
  [libx264 @ 0x7ff609826c00] consecutive B-frames:  1.8%  2.7%  8.5% 87.1%
  
  [libx264 @ 0x7ff609826c00] mb I  I16..4: 25.7% 61.5% 12.8%
  
  [libx264 @ 0x7ff609826c00] mb P  I16..4:  5.3%  5.5%  0.5%  P16..4: 39.9%  6.3%  5.4%  0.0%  0.0%    skip:37.2%
  
  [libx264 @ 0x7ff609826c00] mb B  I16..4:  0.2%  0.4%  0.0%  B16..8: 36.6%  1.5%  0.2%  direct: 0.6%  skip:60.5%  L0:40.3% L1:58.3% BI: 1.3%
  
  [libx264 @ 0x7ff609826c00] 8x8 transform intra:52.6% inter:89.8%
  
  [libx264 @ 0x7ff609826c00] direct mvs  spatial:100.0% temporal:0.0%
  
  [libx264 @ 0x7ff609826c00] coded y,uvDC,uvAC intra: 38.4% 47.1% 8.5% inter: 6.5% 10.0% 0.0%
  
  [libx264 @ 0x7ff609826c00] i16 v,h,dc,p: 34% 18%  8% 39%
  
  [libx264 @ 0x7ff609826c00] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 11%  7% 10% 10% 14% 13% 13% 11% 11%
  
  [libx264 @ 0x7ff609826c00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 16% 11%  6%  8% 13% 12% 12% 10% 12%
  
  [libx264 @ 0x7ff609826c00] i8c dc,h,v,p: 55% 21% 18%  6%
  
  [libx264 @ 0x7ff609826c00] Weighted P-Frames: Y:1.2% UV:0.9%
  
  [libx264 @ 0x7ff609826c00] ref P L0: 57.7% 10.2% 19.2%  5.9%  6.5%  0.5%  0.0%
  
  [libx264 @ 0x7ff609826c00] ref B L0: 82.1% 13.2%  3.6%  1.0%
  
  [libx264 @ 0x7ff609826c00] ref B L1: 94.8%  5.2%
  
  [libx264 @ 0x7ff609826c00] kb/s:934.32

  If I play the original video file in VLC, the frames at the point where the encoding stops go glitchy for a few seconds but then comes good again.

  How can I get around this ? I don't really mind if those few seconds stay glitchy (although it would be nice if that could be fixed) but I do need to re-encode this video, with or without the glitchy couple of seconds...

  Even if I use another program like iFlicks to try and re-encode it does up to the same point and then stops. It also stops at the same point if I use ffmpeg to copy the codecs into a new mp4 container.