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• Tools to determine video orientation

  6 avril 2014, par JayLev

  I receive videos from different devices and want to encode them using the correct orientation.

  I've seen some of examples of how to determine the orientation of a video from a iPhone.

  With exiftool and mediainfo I can indeed tell if an iPhone video has to be rotated.

  However, for android videos, both portrait and landscape videos have the same rotation and matrix structure as each other.

  Maybe this is just with my phone, I'm trying to find videos taken from newer droid phones.

  My question however is whether there's other tools or a different way to determine the orientation that'll work with all devices.

  EDIT :
  I just checked a video from a Samsung Galaxy S II, and I can get the orientation from exiftool. So it's not a problem with all android phones.
  My android phone is a HTC Desire running on android 2.2.

  And actually (I didn't even notice before) a portrait video will not be correctly oriented even when playing on the phone. So I guess it's not about the tools, the orientation data just doesn't seem to be correct at all.

• cvCreateFileCapture always returns "NULL"

  4 août 2012, par user1553247

  I am making an iphone-app with Xcode 4.3.3 and OpenCV 2.4

  I used that "cvCreateFileCapture("simtom.mp4")" to get frame from '.mp4' file but unfortunately, cvCreateFileCapture() always returns "NULL".

  What is the problem ?

  Here is my source code.

   CvCapture *m_pMusicVideo;     
  
  
  
   m_pMusicVideo = cvCreateFileCapture("simtom.mp4");

• Generating 64kbps audio-only mpegts for HTTP Live segmenter to meept 64kbps audio only requirement

  23 avril 2012, par Pobre

  I am trying to convert our mp4 files into mpeg-ts and segment it into .ts files for my iphone app to play. I am using Carson McDonalds's HTTP-Live-Video-Stream-Segmenter-and-Distributor to do that.

  I got his stuff complied and working correctly. I am currently trying to meet Apple's requirement where I need to provide a baseline 64 kbps audio only stream to my m3u8 playlist.
  Carson doesn't seem to have a profile for that.

  I need to be able to generate 64kbps audio-only stream from mp4, and turn that into mpeg-ts for the segmenter into ts. I am trying to find the right ffmpeg command that will validate without problem using Apple's mediastreamvalidator.

  So far I modified an existing encoding profile to try to achieve 64kbps total :

  ffmpeg -er 4 -i %s -f mpegts -acodec libmp3lame -ar 22050 -ab 32k -s 240x180 -vcodec libx264 -b 16k -flags +loop+mv4 -cmp 256 -partitions +parti4x4+partp8x8+partb8x8 -subq 7 -trellis 1 -refs 5 -coder 0 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -bt 64k -maxrate 16k -bufsize 16k -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 -level 30 -aspect 4:3 -r 10 -g 30 -async 2 - | %s %s %s %s %s

  but then when I try to validate it using mediastreamvalidator, it gives error after few ts :

  Playlist Validation : OK

  Segments :

  sample_cell_4x3_64k-00001.ts :

  WARNING : Media segment exceeds target duration of 10.00 seconds by 1.30 seconds (segment duration is 11.30 seconds)

  sample_cell_4x3_64k-00002.ts :

  WARNING : Media segment exceeds target duration of 10.00 seconds by 1.40 seconds (segment duration is 11.40 seconds)

  ....
  ....

  sample_cell_4x3_64k-00006.ts :

  ERROR : (-1) Unknown video codec : 1836069494 (program 0, track 0)
  ERROR : (-1) failed to parse segment as either an MPEG-2 TS or an ES

  sample_cell_4x3_64k-00007.ts :

  ERROR : (-1) Unknown video codec : 1836069494 (program 0, track 0)
  ERROR : (-1) failed to parse segment as either an MPEG-2 TS or an ES

  ....
  ....
  Average segment duration : 10.26 seconds
  Average segment bitrate : 376797.92 bps
  Average segment structural overhead : 349242.17 bps (92.69 %)

  Is there someway I can generate this correctly with just audio which totals 64kbps and turn it into mpeg-ts ready to be segmented and validated correctly ?

  Am I approaching the problem right ?