Recherche avancée

Sur d’autres sites (7771)

• Visualizing Call Graphs Using Gephi

  1er septembre 2014, par Multimedia Mike — General

  When I was at university studying computer science, I took a basic chemistry course. During an accompanying lab, the teaching assistant chatted me up and asked about my major. He then said, “Computer science ? Well, that’s just typing stuff, right ?”

  My impulsive retort : “Sure, and chemistry is just about mixing together liquids and coming up with different colored liquids, as seen on the cover of my high school chemistry textbook, right ?”

  
  
  

  In fact, pure computer science has precious little to do with typing (as is joked in CS circles, computer science is about computers in the same way that astronomy is about telescopes). However, people who study computer science often pursue careers as programmers, or to put it in fancier professional language, software engineers.

  So, what’s a software engineer’s job ? Isn’t it just typing ? That’s where I’ve been going with this overly long setup. After thinking about it for long enough, I like to say that a software engineer’s trade is managing complexity.

  A few years ago, I discovered Gephi, an open source tool for graph and data visualization. It looked neat but I didn’t have much use for it at the time. Recently, however, I was trying to get a better handle on a large codebase. I.e., I was trying to manage the project’s complexity. And then I thought of Gephi again.

  Prior Work
  One way to get a grip on a large C codebase is to instrument it for profiling and extract details from the profiler. On Linux systems, this means compiling and linking the code using the -pg flag. After running the executable, there will be a gmon.out file which is post-processed using the gprof command.

  GNU software development tools have a reputation for being rather powerful and flexible, but also extremely raw. This first hit home when I was learning how to use the GNU tool for code coverage — gcov — and the way it outputs very raw data that you need to massage with other tools in order to get really useful intelligence.

  And so it is with gprof output. The output gives you a list of functions sorted by the amount of processing time spent in each. Then it gives you a flattened call tree. This is arranged as “during the profiled executions, function c was called by functions a and b and called functions d, e, and f ; function d was called by function c and called functions g and h”.

  How can this call tree data be represented in a more instructive manner that is easier to navigate ? My first impulse (and I don’t think I’m alone in this) is to convert the gprof call tree into a representation suitable for interpretation by Graphviz. Unfortunately, doing so tends to generate some enormous and unwieldy static images.

  Feeding gprof Data To Gephi
  I learned of Gephi a few years ago and recalled it when I developed an interest in gaining better perspective on a large base of alien C code. To understand what this codebase is doing for a particular use case, instrument it with gprof, gather execution data, and then study the code paths.

  How could I feed the gprof data into Gephi ? Gephi supports numerous graphing formats including an XML-based format named GEXF.

  Thus, the challenge becomes converting gprof output to GEXF.

  Which I did.

  Demonstration
  I have been absent from FFmpeg development for a long time, which is a pity because a lot of interesting development has occurred over the last 2-3 years after a troubling period of stagnation. I know that 2 big video codec developments have been HEVC (next in the line of MPEG codecs) and VP9 (heir to VP8’s throne). FFmpeg implements them both now.

  I decided I wanted to study the code flow of VP9. So I got the latest FFmpeg code from git and built it using the options "--extra-cflags=-pg --extra-ldflags=-pg". Annoyingly, I also needed to specify "--disable-asm" because gcc complains of some register allocation snafus when compiling inline ASM in profiling mode (and this is on x86_64). No matter ; ASM isn’t necessary for understanding overall code flow.

  After compiling, the binary ‘ffmpeg_g’ will have symbols and be instrumented for profiling. I grabbed a sample from this VP9 test vector set and went to work.

  ./ffmpeg_g -i vp90-2-00-quantizer-00.webm -f null /dev/null
  gprof ./ffmpeg_g > vp9decode.txt
  convert-gprof-to-gexf.py vp9decode.txt > /bigdisk/vp9decode.gexf
  

  Gephi loads vp9decode.gexf with no problem. Using Gephi, however, can be a bit challenging if one is not versed in any data exploration jargon. I recommend this Gephi getting starting guide in slide deck form. Here’s what the default graph looks like :

  
  
  

  Not very pretty or helpful. BTW, that beefy arrow running from mid-top to lower-right is the call from decode_coeffs_b -> iwht_iwht_4x4_add_c. There were 18774 from the former to the latter in this execution. Right now, the edge thicknesses correlate to number of calls between the nodes, which I’m not sure is the best representation.

  Following the tutorial slide deck, I at least learned how to enable the node labels (function symbols in this case) and apply a layout algorithm. The tutorial shows the force atlas layout. Here’s what the node neighborhood looks like for probing file type :

  
  
  

  Okay, so that’s not especially surprising– avprobe_input_format3 calls all of the *_probe functions in order to automatically determine input type. Let’s find that decode_coeffs_b function and see what its neighborhood looks like :

  
  
  

  That’s not very useful. Perhaps another algorithm might help. I select the Fruchterman–Reingold algorithm instead and get a slightly more coherent representation of the decoding node neighborhood :

  
  
  

  Further Work
  Obviously, I’m just getting started with this data exploration topic. One thing I would really appreciate in such a tool is the ability to interactively travel the graph since that’s what I’m really hoping to get out of this experiment– watching the code flows.

  Perhaps someone else can find better use cases for visualizing call graph data. Thus, I have published the source code for this tool at Github.

• How to create a scheduled task – Introducing the Piwik Platform

  28 août 2014, par Thomas Steur — Development

  This is the next post of our blog series where we introduce the capabilities of the Piwik platform (our previous post was How to create a custom theme in Piwik). This time you’ll learn how to execute scheduled tasks in the background, for instance sending a daily email. For this tutorial you will need to have basic knowledge of PHP.

  What can you do with scheduled tasks ?

  Scheduled tasks let you execute tasks regularly (hourly, weekly, …). For instance you can :

  • create and send custom reports or summaries
  • sync users and websites with other systems
  • clear any caches
  • import third-party data into Piwik
  • monitor your Piwik instance
  • execute any other task you can think of

  Getting started

  In this series of posts, we assume that you have already set up your development environment. If not, visit the Piwik Developer Zone where you’ll find the tutorial Setting up Piwik.

  To summarize the things you have to do to get setup :

  • Install Piwik (for instance via git).
  • Activate the developer mode : ./console development:enable --full.
  • Generate a plugin : ./console generate:plugin --name="MyTasksPlugin". There should now be a folder plugins/MyTasksPlugin.
  • And activate the created plugin under Settings => Plugins.

  Let’s start creating a scheduled task

  We start by using the Piwik Console to create a tasks template :

  ./console generate:scheduledtask

  The command will ask you to enter the name of the plugin the task should belong to. I will simply use the above generated plugin name “MyTasksPlugin”. There should now be a file plugins/MyTasksPlugin/Tasks.php which contains some examples to get you started easily :

  class Tasks extends \Piwik\Plugin\Tasks
  
  {
  
      public function schedule()
  
      {
  
          $this->hourly('myTask');  // method will be executed once every hour
  
          $this->daily('myTask');   // method will be executed once every day
  
          $this->weekly('myTask');  // method will be executed once every week
  
          $this->monthly('myTask'); // method will be executed once every month
  
  
  
          // pass a parameter to the task
  
          $this->weekly('myTaskWithParam', 'anystring');
  
  
  
          // specify a different priority
  
          $this->monthly('myTask', null, self::LOWEST_PRIORITY);
  
          $this->monthly('myTaskWithParam', 'anystring', self::HIGH_PRIORITY);
  
      }
  
  
  
      public function myTask()
  
      {
  
          // do something
  
      }
  
  
  
      public function myTaskWithParam($param)
  
      {
  
          // do something
  
      }
  
  }

  A simple example

  As you can see in the generated template you can execute tasks hourly, daily, weekly and monthly by registering a method which represents the actual task :

  public function schedule()
  
  {
  
      // register method remindMeToLogIn to be executed once every day
  
      $this->daily('remindMeToLogIn');  
  
  }
  
  
  
  public function remindMeToLogIn()
  
  {
  
      $mail = new \Piwik\Mail();
  
      $mail->addTo('me@example.com');
  
      $mail->setSubject('Check stats');
  
      $mail->setBodyText('Log into your Piwik instance and check your stats!');
  
      $mail->send();
  
  }

  This example sends you an email once a day to remind you to log into your Piwik daily. The Piwik platform makes sure to execute the method remindMeToLogIn exactly once every day.

  How to pass a parameter to a task

  Sometimes you want to pass a parameter to a task method. This is useful if you want to register for instance one task for each user or for each website. You can achieve this by specifying a second parameter when registering the method to execute.

  public function schedule()
  
  {
  
      foreach (\Piwik\Site::getSites() as $site) {
  
          // create one task for each site and pass the URL of each site to the task
  
          $this->hourly('pingSite', $site['main_url']); 
  
      }
  
  }
  
  
  
  public function pingSite($siteMainUrl)
  
  {
  
      file_get_contents($siteMainUrl);
  
  }

  How to test scheduled tasks

  After you have created your task you are surely wondering how to test it. First, you should write a unit or integration test which we will cover in one of our future blog posts. Just one hint : You can use the command ./console generate:test to create a test. To manually execute all scheduled tasks you can execute the API method CoreAdminHome.runScheduledTasks by opening the following URL in your browser :

  http://piwik.example.com/index.php?module=API&method=CoreAdminHome.runScheduledTasks&token_auth=YOUR_API_TOKEN

  Don’t forget to replace the domain and the token_auth URL parameter.

  There is one problem with executing the scheduled tasks : The platform makes sure they will be executed only once an hour, a day, etc. This means you can’t simply reload the URL and test the method again and again as you would have to wait for the next hour or day. The proper solution is to set the constant DEBUG_FORCE_SCHEDULED_TASKS to true within the file Core/TaskScheduler.php. Don’t forget to set it back to false again once you have finished testing it.

  Starting from Piwik 2.6.0 you can alternatively execute the following command :

  ./console core:run-scheduled-tasks --force --token-auth=YOUR_TOKEN_AUTH

  The option “–force” will make sure to execute even tasks that are not due to run at this time. So you won’t have to modify any files.

  Which tasks are registered and when is the next execution time of my task ?

  The TasksTimetable plugin from the Marketplace can answer this question for you. Simply install and activate the plugin with one click by going to Settings => Marketplace => Get new functionality. It’ll add a new admin menu item under Settings named Scheduled Tasks.

  Publishing your Plugin on the Marketplace

  In case you want to share your task(s) with other Piwik users you can do this by pushing your plugin to a public GitHub repository and creating a tag. Easy as that. Read more about how to distribute a plugin.

  Advanced features

  Isn’t it easy to create scheduled tasks ? We never even created a file ! Of course, based on our API design principle “The complexity of our API should never exceed the complexity of your use case.” you can accomplish more if you want. For instance, you can define priorities, you can directly register methods from different objects and classes, you can specify at which time of a day a task should run and more.

  Would you like to know more about tasks ? Go to our Tasks class reference in the Piwik Developer Zone.

  If you have any feedback regarding our APIs or our guides in the Developer Zone feel free to send it to us.

• ffmpeg error when using non root user

  29 août 2014, par mkern

  I have installed ffmpeg and it works perfect if you are root or using sudo but it errors out when trying to use it as a non-root user. I have performed the same install on a test VPS and it installs without issue so it appears to be isolated to this cPanel server. I haven’t been able to identify why.

  Non-Root :

  > ffmpeg -v debug -i 1.mov 1.avi ffmpeg version N-65949-g0ddb051
  
  > Copyright (c) 2000-2014 the FFmpeg developers   built on Aug 28 2014
  
  > 11:39:47 with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-4)  
  
  > configuration: --enable-gpl --enable-libmp3lame --enable-libvorbis
  
  > --enable-libvpx --enable-libx264   libavutil      54.  7.100 / 54.  7.100   libavcodec     56.  0.101 / 56.  0.101   libavformat    56.  3.100 / 56.  3.100   libavdevice    56.  0.100 / 56.  0.100   libavfilter     5.  0.103 /  5.  0.103   libswscale      3.  0.100 / 
  
  > 3.  0.100   libswresample   1.  1.100 /  1.  1.100   libpostproc    53.  0.100 / 53.  0.100 Splitting the commandline. Reading option '-v' ... matched as option 'v' (set logging level) with argument 'debug'.
  
  > Reading option '-i' ... matched as input file with argument '1.mov'.
  
  > Reading option '1.avi' ... matched as output file. Finished splitting
  
  > the commandline. Parsing a group of options: global . Applying option
  
  > v (set logging level) with argument debug. Successfully parsed a group
  
  > of options. Parsing a group of options: input file 1.mov. Successfully
  
  > parsed a group of options. Opening an input file: 1.mov.
  
  > [mov,mp4,m4a,3gp,3g2,mj2 @ 0x348fc20] Format mov,mp4,m4a,3gp,3g2,mj2
  
  > probed with size=2048 and score=100 [mov,mp4,m4a,3gp,3g2,mj2 @
  
  > 0x348fc20] ISO: File Type Major Brand: qt   [mov,mp4,m4a,3gp,3g2,mj2 @
  
  > 0x348fc20] Before avformat_find_stream_info() pos: 698348 bytes
  
  > read:39602 seeks:1 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x348fc20] All info
  
  > found [mov,mp4,m4a,3gp,3g2,mj2 @ 0x348fc20] After
  
  > avformat_find_stream_info() pos: 169190 bytes read:2333362 seeks:67
  
  > frames:148 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '1.mov':  
  
  > Metadata:
  
  >     major_brand     : qt  
  
  >     minor_version   : 0
  
  >     compatible_brands: qt  
  
  >     creation_time   : 2014-06-05 04:40:27
  
  >     model           : iPhone 5
  
  >     model-eng       : iPhone 5
  
  >     encoder         : 7.1.1
  
  >     encoder-eng     : 7.1.1
  
  >     date            : 2014-06-04T21:40:27-0700
  
  >     date-eng        : 2014-06-04T21:40:27-0700
  
  >     make            : Apple
  
  >     make-eng        : Apple   Duration: 00:00:07.15, start: 0.000023, bitrate: 781 kb/s
  
  >     Stream #0:0(und), 41, 1/600: Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv, smpte170m), 480x360, 1/1200, 710 kb/s, 29.09
  
  > fps, 600 tbr, 600 tbn, 1200 tbc (default)
  
  >     Metadata:
  
  >       rotate          : 90
  
  >       creation_time   : 2014-06-05 04:40:27
  
  >       handler_name    : Core Media Data Handler
  
  >       encoder         : H.264
  
  >     Side data:
  
  >       displaymatrix: rotation of -90.00 degrees
  
  >     Stream #0:1(und), 107, 1/44100: Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s (default)
  
  >     Metadata:
  
  >       creation_time   : 2014-06-05 04:40:27
  
  >       handler_name    : Core Media Data Handler Successfully opened the file. Parsing a group of options: output file 1.avi. Successfully
  
  > parsed a group of options. Opening an output file: 1.avi. Successfully
  
  > opened the file. detected 24 logical cores [graph 0 input from stream
  
  > 0:0 @ 0x34aa3a0] Setting 'video_size' to value '480x360' [graph 0
  
  > input from stream 0:0 @ 0x34aa3a0] Setting 'pix_fmt' to value '0'
  
  > [graph 0 input from stream 0:0 @ 0x34aa3a0] Setting 'time_base' to
  
  > value '1/600' [graph 0 input from stream 0:0 @ 0x34aa3a0] Setting
  
  > 'pixel_aspect' to value '0/1' [graph 0 input from stream 0:0 @
  
  > 0x34aa3a0] Setting 'sws_param' to value 'flags=2' [graph 0 input from
  
  > stream 0:0 @ 0x34aa3a0] Setting 'frame_rate' to value '320/11' [graph
  
  > 0 input from stream 0:0 @ 0x34aa3a0] w:480 h:360 pixfmt:yuv420p
  
  > tb:1/600 fr:320/11 sar:0/1 sws_param:flags=2 [format @ 0x3496b00]
  
  > compat: called with args=[yuv420p] [format @ 0x3496b00] Setting
  
  > 'pix_fmts' to value 'yuv420p' [AVFilterGraph @ 0x348f320]
  
  > query_formats: 4 queried, 3 merged, 0 already done, 0 delayed
  
  > [AVFilterGraph @ 0x34bbe60] Error initializing threading.
  
  > [AVFilterGraph @ 0x34bbe60] Error creating filter 'anull' Error
  
  > opening filters! [AVIOContext @ 0x34967c0] Statistics: 0 seeks, 0
  
  > writeouts [AVIOContext @ 0x348f1e0] Statistics: 2333362 bytes read, 67
  
  > seeks

  [AVFilterGraph @ 0x34bbe60] Error initializing threading.
  [AVFilterGraph @ 0x34bbe60] Error creating filter ’anull’ Error
  opening filters !
  

  As ROOT :

  ffmpeg -v verbose -i 1.mov 1.avi
  
  ffmpeg version N-65949-g0ddb051 Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Aug 28 2014 11:39:47 with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-4)
  
    configuration: --enable-gpl --enable-libmp3lame --enable-libvorbis --enable-libvpx --enable-libx264
  
    libavutil      54.  7.100 / 54.  7.100
  
    libavcodec     56.  0.101 / 56.  0.101
  
    libavformat    56.  3.100 / 56.  3.100
  
    libavdevice    56.  0.100 / 56.  0.100
  
    libavfilter     5.  0.103 /  5.  0.103
  
    libswscale      3.  0.100 /  3.  0.100
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  0.100 / 53.  0.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '1.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 0
  
      compatible_brands: qt  
  
      creation_time   : 2014-06-05 04:40:27
  
      model           : iPhone 5
  
      model-eng       : iPhone 5
  
      encoder         : 7.1.1
  
      encoder-eng     : 7.1.1
  
      date            : 2014-06-04T21:40:27-0700
  
      date-eng        : 2014-06-04T21:40:27-0700
  
      make            : Apple
  
      make-eng        : Apple
  
    Duration: 00:00:07.15, start: 0.000023, bitrate: 781 kb/s
  
      Stream #0:0(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv, smpte170m), 480x360, 710 kb/s, 29.09 fps, 600 tbr, 600 tbn, 1200 tbc (default)
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : 2014-06-05 04:40:27
  
        handler_name    : Core Media Data Handler
  
        encoder         : H.264
  
      Side data:
  
        displaymatrix: rotation of -90.00 degrees
  
      Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-06-05 04:40:27
  
        handler_name    : Core Media Data Handler
  
  [graph 0 input from stream 0:0 @ 0x27ed3a0] w:480 h:360 pixfmt:yuv420p tb:1/600 fr:320/11 sar:0/1 sws_param:flags=2
  
  [graph 1 input from stream 0:1 @ 0x2800700] tb:1/44100 samplefmt:fltp samplerate:44100 chlayout:0x4
  
  Output #0, avi, to '1.avi':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 0
  
      compatible_brands: qt  
  
      make-eng        : Apple
  
      model           : iPhone 5
  
      model-eng       : iPhone 5
  
      make            : Apple
  
      ISFT            : Lavf56.3.100
  
      ICRD            : 2014-06-04T21:40:27-0700
  
      date-eng        : 2014-06-04T21:40:27-0700
  
      Stream #0:0(und): Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 480x360, q=2-31, 200 kb/s, 29.09 fps, 29.09 tbn, 29.09 tbc (default)
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : 2014-06-05 04:40:27
  
        handler_name    : Core Media Data Handler
  
        encoder         : Lavc56.0.101 mpeg4
  
      Stream #0:1(und): Audio: mp3 (libmp3lame) (U[0][0][0] / 0x0055), 44100 Hz, mono, fltp (default)
  
      Metadata:
  
        creation_time   : 2014-06-05 04:40:27
  
        handler_name    : Core Media Data Handler
  
        encoder         : Lavc56.0.101 libmp3lame
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> mpeg4 (native))
  
    Stream #0:1 -> #0:1 (aac (native) -> mp3 (libmp3lame))
  
  Press [q] to stop, [?] for help
  
  *** dropping frame 79 from stream 0 at ts 80
  
  *** dropping frame 113 from stream 0 at ts 114
  
  *** dropping frame 145 from stream 0 at ts 146
  
  *** dropping frame 177 from stream 0 at ts 178
  
  No more output streams to write to, finishing.
  
  frame=  204 fps=0.0 q=27.2 Lsize=     348kB time=00:00:07.15 bitrate= 398.4kbits/s dup=0 drop=4    
  
  video:271kB audio:56kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 6.560985%
  
  Input file #0 (1.mov):
  
    Input stream #0:0 (video): 208 packets read (634624 bytes); 208 frames decoded; 
  
    Input stream #0:1 (audio): 308 packets read (56854 bytes); 308 frames decoded (315392 samples); 
  
    Total: 516 packets (691478 bytes) demuxed
  
  Output file #0 (1.avi):
  
    Output stream #0:0 (video): 204 frames encoded; 204 packets muxed (276993 bytes); 
  
    Output stream #0:1 (audio): 274 frames encoded (315392 samples); 275 packets muxed (57469 bytes); 
  
    Total: 479 packets (334462 bytes) muxed

  strace and strace -e outputs :
  strace non root :
  

   579 clone(child_stack=0x7fd3bfd07ff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|        CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7fd3bfd089d0, tls=0x7fd3bfd08700, child_tidptr=0x7fd3bfd089d0) = 3        2637
  
      580 mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7fd3bed07000
  
      581 mprotect(0x7fd3bed07000, 4096, PROT_NONE) = 0
  
      582 clone(child_stack=0x7fd3bf506ff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|        CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7fd3bf5079d0, tls=0x7fd3bf507700, child_tidptr=0x7fd3bf5079d0) = -        1 EAGAIN (Resource temporarily unavailable)
  
      583 futex(0x253b420, FUTEX_WAKE_PRIVATE, 1) = 1
  
      584 futex(0x253b3f4, FUTEX_CMP_REQUEUE_PRIVATE, 1, 2147483647, 0x253b420, 4) = 2
  
      585 futex(0x253b420, FUTEX_WAKE_PRIVATE, 1) = 1
  
      586 futex(0x7fd3c2d0e9d0, FUTEX_WAIT, 32631, NULL) = 0
  
      587 munmap(0x7fd3bed07000, 8392704)         = 0
  
      588 munmap(0x7fd3c250e000, 8392704)         = 0
  
      589 munmap(0x7fd3c1d0d000, 8392704)         = 0
  
      590 munmap(0x7fd3c150c000, 8392704)         = 0
  
      591 write(2, "\33[1;32m[AVFilterGraph @ 0x253b0a"..., 39[AVFilterGraph @ 0x253b0a0] ) = 39
  
      592 write(2, "\33[1;31mError initializing thread"..., 41Error initializing threading.
  
      593 ) = 41
  
      594 write(2, "\33[1;32m[AVFilterGraph @ 0x253b0a"..., 39[AVFilterGraph @ 0x253b0a0] ) = 39
  
      595 write(2, "\33[1;31mError creating filter 'an"..., 41Error creating filter 'anull'
  
      596 ) = 41
  
      597 write(2, "\33[4;31mError opening filters!\n\33["..., 34Error opening filters!
  
      598 ) = 34

  strace -e non root :

  strace -e open ffmpeg -i 1.mov 5.avi
  
  open("/etc/ld.so.cache", O_RDONLY)      = 3
  
  open("/lib64/libasound.so.2", O_RDONLY) = 3
  
  open("/usr/lib64/libSDL-1.2.so.0", O_RDONLY) = 3
  
  open("/lib64/libpthread.so.0", O_RDONLY) = 3
  
  open("/usr/lib64/libx264.so.142", O_RDONLY) = 3
  
  open("/usr/lib64/libvpx.so.0", O_RDONLY) = 3
  
  open("/usr/local/lib/libvorbisenc.so.2", O_RDONLY) = 3
  
  open("/usr/local/lib/libvorbis.so.0", O_RDONLY) = 3
  
  open("/usr/local/lib/libmp3lame.so.0", O_RDONLY) = 3
  
  open("/lib64/libm.so.6", O_RDONLY)      = 3
  
  open("/lib64/libbz2.so.1", O_RDONLY)    = 3
  
  open("/usr/local/lib/libz.so.1", O_RDONLY) = 3
  
  open("/lib64/librt.so.1", O_RDONLY)     = 3
  
  open("/lib64/libc.so.6", O_RDONLY)      = 3
  
  open("/lib64/libdl.so.2", O_RDONLY)     = 3
  
  open("/usr/local/lib/libogg.so.0", O_RDONLY) = 3
  
  ffmpeg version N-65949-g0ddb051 Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Aug 28 2014 11:39:47 with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-4)
  
    configuration: --enable-gpl --enable-libmp3lame --enable-libvorbis --enable-libvpx --enable-libx264
  
    libavutil      54.  7.100 / 54.  7.100
  
    libavcodec     56.  0.101 / 56.  0.101
  
    libavformat    56.  3.100 / 56.  3.100
  
    libavdevice    56.  0.100 / 56.  0.100
  
    libavfilter     5.  0.103 /  5.  0.103
  
    libswscale      3.  0.100 /  3.  0.100
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  0.100 / 53.  0.100
  
  open("1.mov", O_RDONLY|O_CLOEXEC)       = 3
  
  open("/etc/localtime", O_RDONLY)        = 4
  
  open("/proc/meminfo", O_RDONLY|O_CLOEXEC) = 4
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '1.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 0
  
      compatible_brands: qt  
  
      creation_time   : 2014-06-05 04:40:27
  
      model           : iPhone 5
  
      model-eng       : iPhone 5
  
      encoder         : 7.1.1
  
      encoder-eng     : 7.1.1
  
      date            : 2014-06-04T21:40:27-0700
  
      date-eng        : 2014-06-04T21:40:27-0700
  
      make            : Apple
  
      make-eng        : Apple
  
    Duration: 00:00:07.15, start: 0.000023, bitrate: 781 kb/s
  
      Stream #0:0(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv, smpte170m), 480x360, 710 kb/s, 29.09 fps, 600 tbr, 600 tbn, 1200 tbc (default)
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : 2014-06-05 04:40:27
  
        handler_name    : Core Media Data Handler
  
        encoder         : H.264
  
      Side data:
  
        displaymatrix: rotation of -90.00 degrees
  
      Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-06-05 04:40:27
  
        handler_name    : Core Media Data Handler
  
  open("5.avi", O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0666) = 4
  
  [AVFilterGraph @ 0x26ff4a0] Error initializing threading.
  
  [AVFilterGraph @ 0x26ff4a0] Error creating filter 'anull'
  
  Error opening filters!

  strace root :

   579 clone(child_stack=0x7f4eb7c34ff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|        CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f4eb7c359d0, tls=0x7f4eb7c35700, child_tidptr=0x7f4eb7c359d0) = 3        383
  
      580 mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f4eb6c34000
  
      581 mprotect(0x7f4eb6c34000, 4096, PROT_NONE) = 0
  
      582 clone(child_stack=0x7f4eb7433ff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|        CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f4eb74349d0, tls=0x7f4eb7434700, child_tidptr=0x7f4eb74349d0) = 3        384
  
      583 mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f4eb6433000
  
      584 mprotect(0x7f4eb6433000, 4096, PROT_NONE) = 0
  
      585 clone(child_stack=0x7f4eb6c32ff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|        CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f4eb6c339d0, tls=0x7f4eb6c33700, child_tidptr=0x7f4eb6c339d0) = 3        385
  
      586 mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f4eb5c32000
  
      587 mprotect(0x7f4eb5c32000, 4096, PROT_NONE) = 0
  
      588 clone(child_stack=0x7f4eb6431ff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|        CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f4eb64329d0, tls=0x7f4eb6432700, child_tidptr=0x7f4eb64329d0) = 3        386
  
      589 mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f4eb5431000
  
      590 mprotect(0x7f4eb5431000, 4096, PROT_NONE) = 0
  
      591 clone(child_stack=0x7f4eb5c30ff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|        CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f4eb5c319d0, tls=0x7f4eb5c31700, child_tidptr=0x7f4eb5c319d0) = 3        387
  
      592 mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f4eb4c30000
  
      593 mprotect(0x7f4eb4c30000, 4096, PROT_NONE) = 0
  
      594 clone(child_stack=0x7f4eb542fff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|        CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f4eb54309d0, tls=0x7f4eb5430700, child_tidptr=0x7f4eb54309d0) = 3        388
  
      595 mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f4eb442f000
  
      596 mprotect(0x7f4eb442f000, 4096, PROT_NONE) = 0
  
      597 clone(child_stack=0x7f4eb4c2eff0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|        CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f4eb4c2f9d0, tls=0x7f4eb4c2f700, child_tidptr=0x7f4eb4c2f9d0) = 3        389
  
      598 mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f4eb3c2e000

  strace -e root :

      strace -e open ffmpeg -i 1.mov 5.avi
  
      open("/etc/ld.so.cache", O_RDONLY)      = 3
  
      open("/lib64/libasound.so.2", O_RDONLY) = 3
  
      open("/usr/lib64/libSDL-1.2.so.0", O_RDONLY) = 3
  
      open("/lib64/libpthread.so.0", O_RDONLY) = 3
  
      open("/usr/lib64/libx264.so.142", O_RDONLY) = 3
  
      open("/usr/lib64/libvpx.so.0", O_RDONLY) = 3
  
      open("/usr/local/lib/libvorbisenc.so.2", O_RDONLY) = 3
  
      open("/usr/local/lib/libvorbis.so.0", O_RDONLY) = 3
  
      open("/usr/local/lib/libmp3lame.so.0", O_RDONLY) = 3
  
      open("/lib64/libm.so.6", O_RDONLY)      = 3
  
      open("/lib64/libbz2.so.1", O_RDONLY)    = 3
  
      open("/usr/local/lib/libz.so.1", O_RDONLY) = 3
  
      open("/lib64/librt.so.1", O_RDONLY)     = 3
  
      open("/lib64/libc.so.6", O_RDONLY)      = 3
  
      open("/lib64/libdl.so.2", O_RDONLY)     = 3
  
      open("/usr/local/lib/libogg.so.0", O_RDONLY) = 3
  
      ffmpeg version N-65957-gc6a3b00 Copyright (c) 2000-2014 the FFmpeg developers
  
        built on Aug 28 2014 13:37:32 with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-4)
  
        configuration: --enable-gpl --enable-libmp3lame --enable-libvorbis --enable-libvpx --enable-libx264 --prefix=/usr --libdir=/usr/lib64 --enable-gpl --enable-libmp3lame --enable-libvorbis --enable-libvpx --enable-libx264
  
        libavutil      54.  7.100 / 54.  7.100
  
        libavcodec     56.  0.101 / 56.  0.101
  
        libavformat    56.  3.100 / 56.  3.100
  
        libavdevice    56.  0.100 / 56.  0.100
  
        libavfilter     5.  0.103 /  5.  0.103
  
        libswscale      3.  0.100 /  3.  0.100
  
        libswresample   1.  1.100 /  1.  1.100
  
        libpostproc    53.  0.100 / 53.  0.100
  
      open("1.mov", O_RDONLY|O_CLOEXEC)       = 3
  
      open("/etc/localtime", O_RDONLY)        = 4
  
      open("/proc/meminfo", O_RDONLY|O_CLOEXEC) = 4
  
      Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '1.mov':
  
        Metadata:
  
          major_brand     : qt  
  
          minor_version   : 0
  
          compatible_brands: qt  
  
          creation_time   : 2014-06-05 04:40:27
  
          model           : iPhone 5
  
          model-eng       : iPhone 5
  
          encoder         : 7.1.1
  
          encoder-eng     : 7.1.1
  
          date            : 2014-06-04T21:40:27-0700
  
          date-eng        : 2014-06-04T21:40:27-0700
  
          make            : Apple
  
          make-eng        : Apple
  
        Duration: 00:00:07.15, start: 0.000023, bitrate: 781 kb/s
  
          Stream #0:0(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv, smpte170m), 480x360, 710 kb/s, 29.09 fps, 600 tbr, 600 tbn, 1200 tbc (default)
  
          Metadata:
  
            rotate          : 90
  
            creation_time   : 2014-06-05 04:40:27
  
            handler_name    : Core Media Data Handler
  
            encoder         : H.264
  
          Side data:
  
            displaymatrix: rotation of -90.00 degrees
  
          Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s (default)
  
          Metadata:
  
            creation_time   : 2014-06-05 04:40:27
  
            handler_name    : Core Media Data Handler
  
      File '5.avi' already exists. Overwrite ? [y/N] y
  
      open("5.avi", O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0666) = 4
  
      Output #0, avi, to '5.avi':
  
        Metadata:
  
          major_brand     : qt  
  
          minor_version   : 0
  
          compatible_brands: qt  
  
          make-eng        : Apple
  
          model           : iPhone 5
  
          model-eng       : iPhone 5
  
          make            : Apple
  
          ISFT            : Lavf56.3.100
  
          ICRD            : 2014-06-04T21:40:27-0700
  
          date-eng        : 2014-06-04T21:40:27-0700
  
          Stream #0:0(und): Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 480x360, q=2-31, 200 kb/s, 29.09 fps, 29.09 tbn, 29.09 tbc (default)
  
          Metadata:
  
            rotate          : 90
  
            creation_time   : 2014-06-05 04:40:27
  
            handler_name    : Core Media Data Handler
  
            encoder         : Lavc56.0.101 mpeg4
  
          Stream #0:1(und): Audio: mp3 (libmp3lame) (U[0][0][0] / 0x0055), 44100 Hz, mono, fltp (default)
  
          Metadata:
  
            creation_time   : 2014-06-05 04:40:27
  
            handler_name    : Core Media Data Handler
  
            encoder         : Lavc56.0.101 libmp3lame
  
      Stream mapping:
  
        Stream #0:0 -> #0:0 (h264 (native) -> mpeg4 (native))
  
        Stream #0:1 -> #0:1 (aac (native) -> mp3 (libmp3lame))
  
      Press [q] to stop, [?] for help
  
      frame=  204 fps=0.0 q=27.2 Lsize=     348kB time=00:00:07.15 bitrate= 398.4kbits/s dup=0 drop=4    
  
      video:271kB audio:56kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 6.560985%