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• Rotating videos with FFmpeg

  19 février 2016, par jocull

  I have been trying to figure out how to rotate videos with FFmpeg. I am working with iPhone videos taken in portrait mode. I know how to determine the current degrees of rotation using MediaInfo (excellent library, btw) but I’m stuck on FFmpeg now.

  From what I’ve read, what you need to use is a vfilter option. According to what I see, it should look like this :

  ffmpeg -vfilters "rotate=90" -i input.mp4 output.mp4

  However, I can’t get this to work. First, -vfilters doesn’t exist anymore, it’s now just -vf. Second, I get this error :

  No such filter: 'rotate'
  
  Error opening filters!

  As far as I know, I have an all-options-on build of FFmpeg. Running ffmpeg -filters shows this :

  Filters:
  
  anull            Pass the source unchanged to the output.
  
  aspect           Set the frame aspect ratio.
  
  crop             Crop the input video to x:y:width:height.
  
  fifo             Buffer input images and send them when they are requested.
  
  format           Convert the input video to one of the specified pixel formats.
  
  hflip            Horizontally flip the input video.
  
  noformat         Force libavfilter not to use any of the specified pixel formats
  
   for the input to the next filter.
  
  null             Pass the source unchanged to the output.
  
  pad              Pad input image to width:height[:x:y[:color]] (default x and y:
  
   0, default color: black).
  
  pixdesctest      Test pixel format definitions.
  
  pixelaspect      Set the pixel aspect ratio.
  
  scale            Scale the input video to width:height size and/or convert the i
  
  mage format.
  
  slicify          Pass the images of input video on to next video filter as multi
  
  ple slices.
  
  unsharp          Sharpen or blur the input video.
  
  vflip            Flip the input video vertically.
  
  buffer           Buffer video frames, and make them accessible to the filterchai
  
  n.
  
  color            Provide an uniformly colored input, syntax is: [color[:size[:ra
  
  te]]]
  
  nullsrc          Null video source, never return images.
  
  nullsink         Do absolutely nothing with the input video.

  Having the options for vflip and hflip are great and all, but they just won’t get me where I need to go. I need to the ability to rotate videos 90 degrees at the very least. 270 degrees would be an excellent option to have as well. Where have the rotate options gone ?

• Launch Leech and the History of WMV

  14 septembre 2010, par Multimedia Mike — General

  I was combing through my programming archives again and came across an old Perl script called launch-leech.pl. This was a private script I used to maintain for the benefit of myself and a few friends. See, there was this site called Launch.com (URL doesn’t seem to do anything as of this writing but here’s the Wikipedia page). Purchased by Yahoo ! in 2001, Launch still maintained their independent branding. They also carried a lot of music videos, of which I am a huge junkie. launch-leech.pl was the tool I used to download the videos. This was particularly useful since I stubbornly clung to dialup internet access until mid-2004 and it would have been impossible to stream video at any decent quality (though there were 56k streams, so like I said– not possible at any decent quality).

  
  
  

  Technically
  I followed Launch.com for many years. To be honest, I only “followed” in that I figured out where their “latest videos” URL lived and regularly polled it. Each video had either a 6-, 7-, or 8-digit unique ID that could be plugged into the launch-leech.pl script which would then have a conversation with the relevant servers, determine the correct streaming URL with the highest quality, then download and save the URL by handing it off to an external program (first ASFRecorder, though I later switched to mmsclient).

  At one point, I even wrote a crawler that compiled an offline database of all the videos, their IDs and their metadata. I never thought of anything interesting to do with it, though.

  
  
  

  Windows Media Legacy
  During these glory days of leeching, Launch.com streamed using Windows Media. I admit, it’s a bit of a blur now — the site might have used Real or QuickTime, but I was obviously most in tune with the WM side. I remember when I first found the site circa 2000-2001, the videos were in MS MPEG-4v3, and the high quality bitrate was 300 kbits/sec. Eventually, Launch.com would stream WMV7, WMV8, and finally WMV9, with bitrates up to 700 kbits/sec. However, they never broke free of the 320×240 encoding resolution, which was frustrating. When I wasn’t able to notice any substantial difference between 300 and 700 kbits/sec, I felt it might be time to put those extra bits to work on a resolution upgrade.

  At least they were nice enough to re-encode a number of old videos using better codecs and bitrates with each revision, thus prompting me to scan through the site collecting updated video IDs for download.

  
  
  

  Epilogue
  I don’t clearly remember when I stopped visiting Launch.com. Video-wise, the web has been a blur of Flash video ever since about 2006. Meanwhile, I spent a lot of time collecting a bunch of music videos in the first half of the decade only to find that pretty much every version of every music video made since the dawn of time is available on demand thanks to YouTube. I have found that this phenomenon manifests in many areas as internet technology marches on.

  The Real Entertainment
  The launch-leech.pl tool represents a recurring pattern for me. I derive as much — if not more — entertainment from creating programs like launch-leech.pl (and implicitly reverse engineering something in the process ; in this case, a website) as I do from the intended entertainment media itself. I seem to have this issue a lot with games, too.

  Is this an issue for anyone else ? Am I the only one who would rather play with the box that a shiny toy comes packaged in ?

• FFmpeg fourcc Avi codec support list ?

  5 décembre 2013, par Sugrue

  A couple of similar questions are on stackoverflow, but I haven't been able to figure this exact problem out.

  I want to get a list of the fourccs for the avi codecs that FFMpeg can decode.

  I know how to get all the formats ffmpeg -formats and codecs ffmpeg -codecs but neither list gives me an accessible list of fourccs. Neither does the documentation I can find.

  I need this list, so that my application can access the fourcc of an avi file and determine whether to use ffmpeg or VfW (or DirectX) to try decode the file.

  Is there some ffmpeg command that can give me this list ?