Recherche avancée

Sur d’autres sites (6254)

• Creating a movie from multiple .png files

  21 octobre 2014, par QuantumFool

  I’ve got quite a few .png files, and I need to create a movie out of them. So, I’m going through this tutorial which uses ffmpeg :

  http://www.miscdebris.net/blog/2008/04/28/create-a-movie-file-from-single-image-files-png-jpegs/

  When I go to type the first line (sudo apt-get install ffmpeg), in Terminal and enter my password as appropriate, I get :

  Reading package lists... Done
  
  Building dependency tree       
  
  Reading state information... Done
  
  Package ffmpeg is not available, but is referred to by another package.
  
  This may mean that the package is missing, has been obsoleted, or
  
  is only available from another source
  
  
  
  E: Package 'ffmpeg' has no installation candidate

  That’s funny ; I installed the latest version manually this morning ! Anyway, I proceed with the instructions assuming ffmpeg is installed properly (I’m looking at the file where it downloaded to, so that can’t be the issue) :

  cd Downloads
  
  cd python-meep
  
  cd Images
  
  ffmpeg -qscale 4 -r 20 -b 9600 -i Image%03d.png movie.mp4

  To my surprise, I get :

  ffmpeg: command not found

  I just installed it ! Furthermore, I dragged my manual installation folder into the very same directory with the pictures ! What’s going on ?

  Thanks !

• ffmpeg and Red5 Issue : Increase in number of ffmpeg simultaneous streams to Red5 resulting in packet loss

  30 octobre 2014, par kajarigd

  I have a screen sharing app written in flex, using which one person can share his screen with another person via Red5 server (Version : 1.0.3). Platform is Windows Server 2008. Now, I want to load test this Red 5 server to find out maximum how many simultaneous screen sharing session it can allow, without any quality compromise. By quality I mean, speed of transmission and no data loss during transmission. I simulated the load using ffmpeg command.

  For this, instead of transmitting a live captured screen, I am transmitting (uploading) a FLV file stored in my local to the Red5 server using ffmpeg command. In the receiving client side, I am starting to download (transmitting) this same FLV file after 5 secs since the upload has started. This is working fine when I am running this test for less than 10 pairs of upstreaming-downstreaming sessions. But, when the number is increasing beyond 10, I am observing significant packet loss in transmission.

  Here are the commands I am running in a loop. The loop count is the number of streaming pairs.

  1. upstreaming : ffmpeg -re -i  -f flv -ar 22050 "rtmp://" -report
  2. downstreaming : ffmpeg -re -i "rtmp:// live=1"  -report

  The and are set in such a way, that in the downstream I will download the same uploaded file. "rtmp ://" are the same in both the cases. I am not doing the upstream in record mode, hence, no physical file is getting saved in the server side. When I am analyzing the file I received in the receiving client side, it is a poor quality video due to frame loss. Uploading and downloading machines are two different machines. I ran the test for many hours, repeating the same 10 simultaneous streaming sets. Each set is consistently giving the same results.

  What is puzzling me is, this is working fine without any packet loss for less that 10 simultaneous streaming. I searched about it in various forums, but none of the answers were applicable for this scenario. For a while I was thinking that Red5 has limited capacity, but I found many posts saying Red5 can easily scale up to take very big load. Does that mean, the problem is in my configuration ? I am not sure which are to focus on.

  An example log snippet :

  Lots of missing data at downstream side. For e.g. between frames 101 and 102 there is a difference of 25 sec. On replaying the video there is a stoppage for this much time.In this time gap all the frames are lost.

  frame=  101 fps=1.0 q=14.5 size=    2650kB time=00:01:41.00 bitrate= 214.9kbits/s
  
  frame=  102 fps=1.0 q=13.2 size=    2763kB time=00:02:06.00 bitrate= 179.6kbits/s

  Any help is appreciated !

• configure : Use pkg-config for libdc1394 discovery

  22 février 2015, par Vittorio Giovara

  configure : Use pkg-config for libdc1394 discovery
  Since not all systems need the libraw1394 dependency, let pkg-config
  
  provide the list of libraries actually needed.
  The libdc1394-2.pc file has been included since version 2 (2008-01-05),
  
  so it should be safe to use.
  

  • [DBH] configure