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• ARM compiler update

  15 janvier 2010, par Mans — ARM, Compilers

  Since my last shootout, all the tested vendors have updated their compilers. Here is a quick update on each of them.

  Both the 4.3 and 4.4 branches of FSF GCC have had bugfix releases, bringing them to 4.3.4 and 4.4.2, respectively. Neither update contains anything particularly noteworthy.

  The CodeSourcery 2009q3 release sees an update to a GCC 4.4 base, a significant change from the 4.3 base used in 2009q1. The update is a mixed blessing. In fact, it is mostly a curse and hardly a blessing at all. On the bright side, the floating-point speed regressions in 2009q1 are gone, 2009q3 being a few per cent faster even than 2007q3. Unfortunately, this improvement is completely overshadowed by a major speed regression on integer code, a whopping 24% in one case. This ties in with the slowdown previously observed with FSF GCC 4.4 compared to 4.3.

  ARM RVCT 4.0 is now at Build 697. This update fixes some bugs and introduces others. Notably, it no longer builds FFmpeg correctly. The issue has been reported to ARM.

  Texas Instruments, finally, have made a formal release, v4.6.1, of their TMS470 compiler incorporating various fixes allowing it to build a moderately patched FFmpeg. The performance remains somewhere between GCC and RVCT on average.

  In light of the above, my recommendations remain unchanged :

  • For a free compiler, choose CodeSourcery 2009q1. It beats GCC 4.3.4 by 5-10% in most cases.
  • GNU purists are best served by GCC 4.3.4, which is up to 20% faster than 4.4.2 and rarely slower.
  • When price is not a concern, ARM RCVT is a good option, outperforming GCC by up to a factor 2.
  • In all cases, disable any auto-vectorisation features.

  Regardless of which compiler is chosen, I cannot overstress the importance of testing. All compilers are crawling with bugs, and even the most innocent-looking code change can trigger one of them. When using a compiler other than GCC, extra caution is advised considering a lot of code is developed using only GCC and may thus fall prey to bugs unique to said other compiler.

• How to cut video frame specific with ffmpeg and convert framerate ?

  1er mars 2018, par Alexander Pospischil

  since a couple of days i encounter a problem with ffmpeg which is actually driving me mad...
  I try to use FFMPEG’s filter_complex in order to extract certain short segments of a videofile (shot at 60fps). I know the exact frames from the original footage which i want to use for cutting. I use the trim filter command together with setpts, if i want to change the speed of each snippet.
  In the actual case i want to have the first snippet in original speed (1.0), and the resulting output video should be at 30fps instead of the original footages 60fps.
  Here’s the code i’m using :

  ffmpeg -y -i footage60fps -filter_complex " 
  
  [0:v]trim=start_frame=28:end_frame=82,setpts=PTS-
  
  STARTPTS,setpts=1.0*PTS[v0]; 
  
  [0:v]trim=start_frame=10:end_frame=20,setpts=PTS-
  
  STARTPTS,setpts=2.0*PTS[v1]; [v0][v1]concat=n=2:v=1:a=0[out] " -map [out] -
  
  preset ultrafast -r 30 output30fps.mp4

  The result i’m expecting would be, that in the first snippet (frame 28 until last before 82) ffmpeg would drop every second frame ([x]) in order to have it converted from 60fps to 30fps at normal speed :
  [28][x][30][x][32][x]...[80]

  However, the result i get is :
  [28][29][30][31][x][33][x][35][x]...[81]

  Does anybody understand this behavior ? How could i solve it ? It seems like a minor issue, but it turns out to be so annoying when cutting sharp on music etc... Any help would be highly appreciated !

• Permission denied when trying to call ffmpeg on heroku

  1er décembre 2013, par chuck w

  I have a rails 3.1 web app on Heroku (cedar) that that allows users to post stories with photo and video attachments using the paperclip gem (3.5.1). Uploads are stored on s3. This has been working 100% for many months.

  I have recently added video transcoding and thumbnailing to my dev machine with the paperclip-ffmpeg gem (1.0.1) and ffmpeg running locally. This is also working.

  I've followed these instructions to build and install ffmpeg on heroku, and I've altered my Heroku app's path so that it reads as follows :

  PATH:   bin:vendor/ffmpeg/bin:vendor/bundle/ruby/1.9.1/bin:/usr/local/bin:/usr/bin:/bin

  and my app's LD_LIBRARY_PATH so that it reads as follows :

  LD_LIBRARY_PATH:             vendor/ffmpeg/lib:/usr/local/lib

  Finally, I've vendored ffmpeg into my app with the following structure :

  

  When I commit and push these changes to Heroku and POST a story that has a video I get the following output on Heroku logs :

  2013-11-30T22:51:46.711010+00:00 app[web.1]: Started POST "/stories" for 71.80.218.93 at        
  
  2013-11-30 22:51:46 +0000
  
  2013-11-30T22:51:47.023119+00:00 app[web.1]: Cocaine::ExitStatusError (Command 'ffprobe 
  
  "/tmp/sideways video20131130-2-14w1q4j.mp4" 2>&1' returned 126. Expected 0
  
  2013-11-30T22:51:47.023119+00:00 app[web.1]: Here is the command output:
  
  2013-11-30T22:51:47.023119+00:00 app[web.1]: 
  
  2013-11-30T22:51:47.023119+00:00 app[web.1]:   app/controllers/stories_controller.rb:11:in     
  
  `create'
  
  2013-11-30T22:51:47.023119+00:00 app[web.1]: 
  
  2013-11-30T22:51:47.023119+00:00 app[web.1]: 
  
  2013-11-30T22:51:47.019228+00:00 heroku[router]: at=info method=POST path=/stories     
  
  host=myapp.herokuapp.com fwd="71.80.218.93" dyno=web.1 connect=1ms    
  
  service=3130ms status=500 bytes=754
  
  2013-11-30T22:51:47.023119+00:00 app[web.1]: 
  
  2013-11-30T22:51:47.023600+00:00 app[web.1]: cache: [POST /stories] invalidate, pass
  
  2013-11-30T22:51:47.023119+00:00 app[web.1]: sh: ffprobe: Permission denied
  
  2013-11-30T22:51:47.023119+00:00 app[web.1]: ):

  Also, running the console command : heroku run "ffmpeg -version" -a myapp
  returns :

  Running ffmpeg -version attached to terminal... up, run.6591
  
  bash: vendor/ffmpeg/bin/ffmpeg: Permission denied

  Here is my Post model paperclip set-up :

  class Post < ActiveRecord::Base
  
  
  
    attr_accessible :contents, :photo, :video
  
  
  
    belongs_to    :story, :touch => true
  
    belongs_to    :user, :touch => true
  
  
  
    has_attached_file :photo, 
  
                      :styles => { 
  
                        :thumb => ["100x140>", :jpg],
  
                        :medium => ["400x400>", :jpg],
  
                        :large => ["800x800>", :jpg]
  
                      },
  
                      :processors => [:thumbnail],
  
                      :storage => :s3,
  
                      :s3_credentials => "#{Rails.root.to_s}/config/s3.yml",
  
                      :path => "/:style/:id/:filename"
  
  
  
    has_attached_file :video, 
  
                      :storage => :s3,
  
                      :s3_credentials => "#{Rails.root.to_s}/config/s3.yml",
  
                      :path => "/video/:id/:filename",
  
                      :styles => {
  
                        :thumb => { :geometry => "140x100#", :format => 'jpg', :time => 10 },
  
                        :medium => { :geometry => "480x360", :format => 'mp4' },
  
                      }, :processors => [:ffmpeg]

  Why am I getting these "permission denieds" ? Any help would be greatly appreciated !!!