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• Web Based Playback of iOS Videos with Orientation Flag

  3 mars 2012, par shanee

  We just recently created an iPhone app for one of our system that allows users to upload picture and video content to our services. The last major hitch we are running into is how to handle videos that are uploaded in an orientation other than Horizontal Right. Apparently if your playback system does not account for the orientation flag sent with the video then it will play upside down or sideways.

  The correct approach appears to be that the playback system should take the orientation flag into account just prior to playback. This is the way Apple handles it directly on the device as well as through Quicktime.

  SO my first hope is that someone is aware of a web based (HTML5 or Flash) player that is capable of rotating a video during playback based on either the video orientation metadata or based on a passed flag (we already have the necessary flag available in the DB if we need to just pass it manually). If you know of any such player then PLEASE SHARE !

  If you aren't aware of such a player, then has anyone had any luck rotating their videos using FFMPEG or MEncoder ? We did a few hours of testing last week and weren't able to get any decent results from the two heavy hitters mentioned there.

  Failing ALL OF THAT, is it possible to have the iPhone upload a video or image in a specified direction ?

  Any of the three will work for me, but I would prefer to do whatever is standard (if one exists).

  Any help is much appreciated !

• ffmpeg : 1 image + 1 audio file = 1 video [on hold]

  15 février 2016, par matteo

  This should be pretty trivial but I can’t find a way to get it to work.

  I want ffmpeg to take one jpg image and an audio file as input and generate a video file of the same duration as the audio file (by stretching the still image for the whole duration).

  I don’t care very much about what video codec is used for output but it is vital that I can use "copy" as the audio codec (i.e. copy the audio stream without transcoding it).

  What is the right command line that would do that ?

  I tried :

  ffmpeg -i image8.jpg -i sound11.amr -acodec copy test.avi

  and tried a lot of combinations with and without -s 640x360, -loop_input, -shortest, -t xxx, -r 0.1 (artificially low frame rate in the hope that the video would be longer) and -f image2

  Either I get errors or I get a video file of the duration of one frame.

  I’ve googled around and found a dozen of proposed solutions (supposedly to this very same question) none of which works.

  Can anybody suggest a working command and explaing the rationale behind it ?

• SOLVED : ffmpeg keeps converting second ac3 audio stream to mp2

  27 janvier 2015, par user1121445

  I’m new to this forum, and hope someone can help.
  I am trying to add a second audio track (chinese.ac3) to an XVID video (vts_01.avi) that already has an ac3 track.

  These audio tracks are encoded to ac3, 48000 Hz, stereo, 128 kb/s, and I would like to keep them that way — just multiplex the streams without transcoding.

  This is the command I am using :

  ffmpeg -i vts_01.avi -vcodec copy -i Chinese.ac3 -acodec copy -map 0:0 -map 0:1 -map 1:0 muxed2.avi -newaudio

  ffmpeg does its work, except for the fact that it converts the second track to mp2, 64 kb/s.

  Here is a relevant excerpt from the output, where the key part is ’Stream #0.2 : Audio : mp2, 48000 Hz, stereo, s16, 64 kb/s’ where I would like ’Stream #0.2 : Audio : ac3, 48000 Hz, stereo, 128 kb/s’ :

  Input #0, avi, from 'vts_01.avi':
  
    Metadata:
  
      encoder         : Lavf53.5.0
  
    Duration: 02:03:26.40, start: 0.000000, bitrate: 1954 kb/s
  
      Stream #0.0: Video: mpeg4, yuv420p, 720x352 [PAR 1:1 DAR 45:22], 23.98 tbr,
  
  23.98 tbn, 23.98 tbc
  
      Stream #0.1: Audio: ac3, 48000 Hz, stereo, s16, 128 kb/s
  
  [ac3 @ 018A7440] max_analyze_duration 5000000 reached at 5024000
  
  [ac3 @ 018A7440] Estimating duration from bitrate, this may be inaccurate
  
  Input #1, ac3, from 'Chinese.ac3':
  
    Duration: 02:03:26.36, start: 0.000000, bitrate: 128 kb/s
  
      Stream #1.0: Audio: ac3, 48000 Hz, stereo, s16, 128 kb/s
  
  File 'muxed2.avi' already exists. Overwrite ? [y/N] y
  
  Output #0, avi, to 'muxed2.avi':
  
    Metadata:
  
      ISFT            : Lavf53.5.0
  
      Stream #0.0: Video: mpeg4, yuv420p, 720x352 [PAR 1:1 DAR 45:22], q=2-31, 23.
  
  98 tbn, 23.98 tbc
  
      Stream #0.1: Audio: ac3, 48000 Hz, stereo, 128 kb/s
  
      Stream #0.2: Audio: mp2, 48000 Hz, stereo, s16, 64 kb/s
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
    Stream #0.1 -> #0.1
  
    Stream #1.0 -> #0.2

  I have tried a number of different combinations, including explicitly forcing the stream to ac3 with :

  ffmpeg -i vts_01.avi -vcodec copy -i chinese.ac3 -acodec ac3 -ac 2 -ar 48000 -ab 128k -map 0:0 -map 0:1 -map 1:0 muxed2.avi -newaudio

  Same result.

  I have also tried to assign a codec to the stream with stream specifier(based on http://ffmpeg.org/ffmpeg.html#toc-Stream-specifiers-1, but these options are not recognized by my ffmpeg.

  I am running out of things to try. Any help will be appreciated.