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• AR Drone 2.0 video streaming whitout SDK on iOS

  10 janvier 2014, par JosephITA

  I'm coding an app for iOS that interact with the AR Drone 2.0 without using the SDK (poor documentation on the iPhone example).
  At the moment I can send command and receive navdata.
  I have no idea in how to receive video streaming. I know that is an H.264 stream and that I can use ffmpeg, but I'm not sure that this solution will pass the Apple revision.
  Any ideas ?

• Why frame->pts increases by 20, rather than by 1 ?

  19 mars 2013, par user1914692

  Following the exmaples of ffmpeg : decoding_encoding.c and filtering_video.c, I process one video file taken by iPhone. The video file : .mov, video dimensions ; 480x272, video Codec : H.264/AVC, 30 frames per second, bitrate : 605 kbps.

  I first extract each frame, which is YUV.
  I convert YUV to RGB24, and process the RGB24, then write the RGB24 to a .ppm file. It shows the .ppm file is correct.

  Then I plan to encode processed RGB24 frames to a video file.
  Since MPEG does not support RGB24 picture format, I used AV_CODEC_ID_HUFFYUV.
  But the output video file (showing 18.5 MB) does not play. Movie Player on Ubuntu claims an error : Could not determine type of stream.
  I also tried it on VCL. It simply does not work, without any error information.

  My second questions is :
  For each extracted fram from the input video file, I get its pts as follows according to filtering_video.c :

  frame->pts = av_frame_get_best_effort_timestamp(frame);

  I print out each frame's pts, and find that it increases by 20, like below :

  pFrameRGB_count: 0,  frame->pts: 0
  
  pFrameRGB_count: 1,  frame->pts: 20
  
  pFrameRGB_count: 2,  frame->pts: 40
  
  pFrameRGB_count: 3,  frame->pts: 60

  Where frame is the extracted frame from the input video, and pFrameRGB_count is the count for processed frame in RGB24 form.

  Why are they wrong ?

• Rails : Encoder error when converting video using FFMPEG on Heroku

  2 janvier 2013, par andmcgregor

  I'm trying to upload a video and convert the file to mp4 and reduce the file size using the paperclip-ffmpeg and paperclip gems. Everything works fine running a local server and I'm only getting this problem on heroku. I have ffmpeg installed in vendor/ffmpeg/ (I followed these steps : https://gist.github.com/3963576). Here is the code I've got and the error I'm getting :

  models/video.rb :

  class Video < ActiveRecord::Base
  
    attr_accessible :content, :user_id, :video
  
    has_attached_file :video , :styles => { 
  
      :medium => { :geometry => "500x500", :format => 'mp4',
  
          :convert_options => { :output => { :vcodec => 'libx264',
  
          :b => '1000k', :bt => '200k',
  
          :acodec => 'libfaac', :ab => '56k', :ac => 2 } } }
  
    }, :processors => [:ffmpeg]
  
  
  
    belongs_to :user
  
  end

  when I run heroku logs :

  2013-01-02T00:38:20+00:00 app[web.1]: Started POST "/videos" for 101.170.255.251 at 2013-01-02 00:38:20 +0000
  
  2013-01-02T00:38:20+00:00 app[web.1]: Processing by VideosController#create as HTML
  
  2013-01-02T00:38:20+00:00 app[web.1]:   Parameters: {"utf8"=>"✓", "authenticity_token"=>"X0IKts46TF8aFvEb1I/szFo/28omlVBXIIyJ3APz3YA=", "video"=>{"content"=>"", "video"=>#quicktime\r\n", @tempfile=#tmp/RackMultipart20130102-2-1ch9zcp>>}, "commit"=>"Post"}
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] ffmpeg -i "/tmp/sample20130102-2-4j5sgh.mov" 2>&1
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Resize
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Command Success
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Making...
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Building Destination File: 'sample20130102-2-4j5sgh' + 'mp4'
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Destination File Built
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Adding Source
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Adding Geometry
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Convert Options: 500x280
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Adding Format
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] -i :source -y -vcodec libx264 -b 1000k -bt 200k -acodec libfaac -ab 56k -ac 2 -s 500x280 :dest
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Extracting Target Dimensions
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Building Parameters
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Target Size is Available
  
  2013-01-02T00:38:20+00:00 app[web.1]: [paperclip] [ffmpeg] Keeping Aspect Ratio
  
  2013-01-02T00:38:20+00:00 app[web.1]: Command :: ffmpeg -i '/tmp/sample20130102-2-4j5sgh.mov' -y -vcodec libx264 -b 1000k -bt 200k -acodec libfaac -ab 56k -ac 2 -s 500x280 '/tmp/sample20130102-2-4j5sgh20130102-2-1mr35ix.mp4'
  
  2013-01-02T00:38:20+00:00 app[web.1]: ffmpeg version git-2013-01-01-d079d1d Copyright (c) 2000-2012 the FFmpeg developers
  
  2013-01-02T00:38:20+00:00 app[web.1]:   built on Jan  1 2013 12:59:49 with gcc 4.4.3 (Ubuntu 4.4.3-4ubuntu5)
  
  2013-01-02T00:38:20+00:00 app[web.1]:   configuration: --enable-shared --disable-asm --prefix=/app/vendor/ffmpeg
  
  2013-01-02T00:38:20+00:00 app[web.1]:   libavfilter     3. 30.102 /  3. 30.102
  
  2013-01-02T00:38:20+00:00 app[web.1]:   libavcodec     54. 85.100 / 54. 85.100
  
  2013-01-02T00:38:20+00:00 app[web.1]:   libavdevice    54.  3.102 / 54.  3.102
  
  2013-01-02T00:38:20+00:00 app[web.1]:   libavutil      52. 13.100 / 52. 13.100
  
  2013-01-02T00:38:20+00:00 app[web.1]:   libswresample   0. 17.102 /  0. 17.102
  
  2013-01-02T00:38:20+00:00 app[web.1]:   libswscale      2.  1.103 /  2.  1.103
  
  2013-01-02T00:38:20+00:00 app[web.1]:   libavformat    54. 58.100 / 54. 58.100
  
  2013-01-02T00:38:21+00:00 app[web.1]:     creation_time   : 2013-01-02 00:36:58
  
  2013-01-02T00:38:21+00:00 app[web.1]:     minor_version   : 0
  
  2013-01-02T00:38:21+00:00 app[web.1]:     major_brand     : qt  
  
  2013-01-02T00:38:21+00:00 app[web.1]: Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/sample20130102-2-4j5sgh.mov':
  
  2013-01-02T00:38:21+00:00 app[web.1]:     model           : iPhone 4
  
  2013-01-02T00:38:21+00:00 app[web.1]:     compatible_brands: qt  
  
  2013-01-02T00:38:21+00:00 app[web.1]:     model-eng       : iPhone 4
  
  2013-01-02T00:38:21+00:00 app[web.1]:     make-eng        : Apple
  
  2013-01-02T00:38:21+00:00 app[web.1]:     date-eng        : 2012-12-28T00:39:34+1100
  
  2013-01-02T00:38:21+00:00 app[web.1]:     encoder         : 6.0
  
  2013-01-02T00:38:21+00:00 app[web.1]:     encoder-eng     : 6.0
  
  2013-01-02T00:38:21+00:00 app[web.1]:   Duration: 00:00:00.03, start: 0.000000, bitrate: 9465 kb/s
  
  2013-01-02T00:38:21+00:00 app[web.1]:     Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 75 kb/s
  
  2013-01-02T00:38:21+00:00 app[web.1]:     date            : 2012-12-28T00:39:34+1100
  
  2013-01-02T00:38:21+00:00 app[web.1]:       creation_time   : 2013-01-02 00:36:58
  
  2013-01-02T00:38:21+00:00 app[web.1]:     make            : Apple
  
  2013-01-02T00:38:21+00:00 app[web.1]:   Metadata:
  
  2013-01-02T00:38:21+00:00 app[web.1]:     Metadata:
  
  2013-01-02T00:38:21+00:00 app[web.1]:       handler_name    : Core Media Data Handler
  
  2013-01-02T00:38:21+00:00 app[web.1]:     Stream #0:1(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 640x360 [SAR 1:1 DAR 16:9], 8605 kb/s, 30 fps, 30 tbr, 600 tbn, 1200 tbc
  
  2013-01-02T00:38:21+00:00 app[web.1]:     Metadata:
  
  2013-01-02T00:38:21+00:00 app[web.1]:       handler_name    : Core Media Data Handler
  
  2013-01-02T00:38:21+00:00 app[web.1]: Unknown encoder 'libx264'
  
  2013-01-02T00:38:21+00:00 app[web.1]: Please use -b:a or -b:v, -b is ambiguous
  
  2013-01-02T00:38:21+00:00 app[web.1]:       creation_time   : 2013-01-02 00:36:58
  
  2013-01-02T00:38:21+00:00 app[web.1]: [paperclip] An error was received while processing: #
  
  2013-01-02T00:38:21+00:00 app[web.1]:   Rendered videos/new.html.erb within layouts/application (3.2ms)
  
  2013-01-02T00:38:21+00:00 heroku[router]: at=info method=POST path=/videos host=stark-sea-5654.herokuapp.com fwd=101.170.255.251 dyno=web.1 queue=0 wait=0ms connect=3ms service=3685ms status=200 bytes=1878
  
  2013-01-02T00:38:21+00:00 app[web.1]:   Rendered layouts/_footer.html.erb (0.0ms)
  
  2013-01-02T00:38:21+00:00 app[web.1]: Completed 200 OK in 342ms (Views: 124.8ms | ActiveRecord: 10.4ms)
  
  2013-01-02T00:38:21+00:00 app[web.1]:   Rendered layouts/_header.html.erb (1.2ms)

  Everything works fine until the message Unknown encoder 'libx264' so I'm thinking it's something to do with ffmpeg perhaps ?