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• How to change ffmpeg -threads settings [migrated]

  5 août 2014, par Jacob

  Working on a tube site. I’m running videos through ffmpeg on a linux dedicated server to convert to mp4.

  The server specs :

  Architecture:          x86_64
  
  CPU op-mode(s):        32-bit, 64-bit
  
  Byte Order:            Little Endian
  
  CPU(s):                8
  
  On-line CPU(s) list:   0-7
  
  Thread(s) per core:    2
  
  Core(s) per socket:    4
  
  Socket(s):             1
  
  NUMA node(s):          1
  
  Vendor ID:             GenuineIntel
  
  CPU family:            6
  
  Model:                 60
  
  Stepping:              3
  
  CPU MHz:               3491.749
  
  BogoMIPS:              6983.49
  
  Virtualization:        VT-x
  
  L1d cache:             32K
  
  L1i cache:             32K
  
  L2 cache:              256K
  
  L3 cache:              8192K
  
  NUMA node0 CPU(s):     0-7

  Issue during testing is that even only doing 4-5 at once, the server load skyrockets to an average of around 36. This is just a single person. I imagine when it opens, many people will be uploading at once.

  It seems ffmpeg tries to use all the resources available per conversion.

  I’ve heard there’s a -threads setting you can change, but I cannot find it. I have an 8 cpu server. It’s only used for conversions, so I’ve heard the best setting would be between 2 and 4. I can test it out.

  But how do I change this setting ? Everything I see online discusses this setting, but not the steps to change it.

• Solution for VB6 to broadcast Webcam

  11 juillet 2014, par vantrung -cuncon

  Sorry, I know VB6 is decades ago, but I’m in a situation that I have to use VB6 to deliver live webcam stream beetween 2 PC in Server - Client Model program. Vb6-code holds the connection then I have no choice but to transfer all data via that connection.

  I’ve tried weeks for this, uncountable approaches but went to nowhere.
  My efforts focused on 3 major approaches :

  1/ Use ffmpeg to record live webcam as ".avi" file on hard disk, transfer parts of file to other end & play it. But I’ve stucked with a media-player that can play a "being written" avi file.

  Windows Media Player control told me "file already in use..." & VLC Plugin can’t even be added to VB6 (axvlc.dll).

  2/ Use ffmpeg to save live webcam as avi file, transfer each bit of that file to the other end, then in other end, extract 24 images / second from the avi to display continously in a picture box.
  This approach is ok except that my hard disk get fulled of images in a time of wink and my program get very slow before hanging.

  3/ Use ffmpeg to stream the live webcam to a rtp-port like this :

  ffmpeg -f dshow -i video="Lenovo EasyCamera" -vcodec mpeg2video -pix_fmt yuv422p -f rtp -an rtp://224.1.2.3:8191

  I’ve successfully watch the stream in VLC, but VLC(axvlc.dll) refused to be integrated into ancient VB6. And more important, I don’t know how to redirect/reroute the rtp stream to other PC with VB6.

  Any one please light me up ? (Any 3rd party component is welcomed)

• FFMPEG Scene Detection - Trim Blank Background from Video at the Start and End

  10 juin 2014, par user3521682

  Summary :
  Need to programatically trim video when scene is not changing at the beginning & end.

  Example video : http://www.filehosting.co.nz/finished3.mp4
  (Quality is much higher in the real video)

  Background :

  Large number of videos for online store, each video begins with a blank background, then the model walks on (at a random time, few seconds), and then walks off after a random time (around 15 seconds). The end of the video is trimmed seemingly random ; could be up to 15 seconds of ’nothing’ at the end of the video.

  The camera does not move. There is no sound on the videos.
  The videos come from a camera in MOV format, sideways.

  I already have FFMPEG converting from MOV to MP4, rotating the video, adding an audio-track, and trimming the audio at the end of the video.

  Research :
  I understand that I should probably re-encode video with a very high (?) tolerance for i-frames (so that only two are made per video) and then export the times to a text file, and use the text file to cut the video (probably parse it in BASH and use that to build the FFMPEG commands).

  Does anyone have any idea how I could generate just two key-frames per video ?

  Example video : http://www.filehosting.co.nz/finished3.mp4
  (Quality is much higher in the real video)