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• Video created with ffmpeg won't play in video player

  11 octobre 2014, par user3180253

  I’m using Python to create a video using ffmpeg. The following code is what I’m using...

  import subprocess as sp
  
  import Image
  
  FFMPEG_BIN = "ffmpeg"
  
  
  
  commandWriter = [ FFMPEG_BIN,
  
                '-y',
  
                '-f', 'image2pipe',
  
                '-vcodec','mjpeg',
  
                '-s', '480x360', # size of one frame
  
                '-pix_fmt', 'rgb24',
  
                '-r', '29', # frames per second
  
                '-i', '-',
  
                '-an', # Tells FFMPEG not to expect any audio
  
                '-vcodec', 'mpeg4',
  
                '-qscale', '5',
  
                '-r', '29',
  
                '-b', '250',
  
                './fire.mp4' ]
  
  
  
  pipeWriter = sp.Popen(commandWriter, stdin=sp.PIPE)
  
  
  
  fps, duration = 24, 10
  
  for i in range(fps*duration):
  
     im = Image.new("RGB",(480,360),(i%250,1,1))
  
     im.save(pipeWriter.stdin, "JPEG")
  
  pipeWriter.stdin.close()
  
  pipeWriter.wait()
  
  
  
  pipeWriter.terminate()

  After running the above code, I get an output video with a data rate of 214 kbps. This video won’t play in Windows Media Player. At first I was at a loss of how to get the video to play, so I compared it to another video that I downloaded. I noticed the only real difference was in the bit rates/data rates. I ran this command from the command line...

  ffmpeg -i fire.mp4 -b:v 250k -bufsize 250k water.mp4

  which as I understand it takes fire.mp4 and simply outputs a new video with a modified bit rate. This new output works when I open it in Windows Media Player.

  The question I’m asking is how can I do this straight from Python ? I’ve tried adding a -b option to commandWriter (as shown) but this does not work. I’ve also added a bufsize = 10**8 in my pipeWriter but that does not work either.

  Overall what I’m trying to accomplish is taking a video input.mp4, modifying each frame as I load it in memory, and then writing that frame to a new file output.mp4. So far ffmpeg is looking like the best tool ’cause I can’t get OpenCV to work at all.

  So if anyone has a way to have a water.mp4 output file be able to run in Windows Media Player without needing to have that additional command line code run or a better way to complete my overall task, I would much appreciate that.

• Why is long video taking long time before VideoJS player gets metadata to start playing ?

  7 mars 2015, par Tom Jenkinson

  Does anyone know why it is taking so long before the loadedmetadata event is fired for longer videos ?

  Here is an example : https://www.la1tv.co.uk/player/124/260

  I can see in developer tools that the file is still downloading when the event is fired, so it’s not like it’s having to download the whole file, it’s just having to get quite far though before the event is fired.

  The ffmpeg command I am using to encode the video from java is :

  RuntimeHelper.executeProgram(new String[] {config.getString("ffmpeg.location"), "-y", "-nostdin", "-timelimit", ""+config.getInt("ffmpeg.videoEncodeTimeLimit"), "-progress", ""+f.progressFile.getAbsolutePath(), "-i", source.getAbsolutePath(), "-vf", "scale=trunc(("+f.h+"*a)/2)*2:"+f.h, "-strict", "experimental", "-acodec", "aac", "-b:a", f.aBitrate+"k", "-ac", "2", "-ar", "48000", "-vcodec", "libx264", "-vprofile", "main", "-g", "48", "-b:v", f.vBitrate+"k", "-maxrate", f.vBitrate+"k", "-bufsize", f.vBitrate*2+"k", "-preset", "medium", "-crf", "16", "-vsync", "vfr", "-af", "aresample=async=1000", "-movflags", "+faststart", "-r", f.fr+"", "-f", "mp4", f.outputFile.getAbsolutePath()}, workingDir, null, null);

  which can be found here.

  It has the faststart flag set and I thought this meant the metadata would be inserted right at the beginning of the file ?

  Could it be an issue with the encode settings ?

  Thanks !

• HTML5 video player doesn't work on iPad/iPhone

  16 avril 2015, par Avrohom Yisroel

  NOTE This turned out to be a simulator problem, not a video encoding problem, see my edit lower down...

  I’m creating a web site for a local college, and they want to be able to add short videos that people can view online. I’ve spent quite a bit of time trying to work out how to get the videos to play on iDevices, but have failed.

  I’m using Video.js (http://www.videojs.com), and have HTML that looks like this...

  <video class="video-js vjs-default-skin" controls="controls" preload="auto" width="640" height="352" poster="/Content/Images/logobg.png" data-setup="{}">
  
    <source src="/Content/Videos/video.m4v" type="video/mp4">
  
    <source src="/Content/Videos/video.webm" type="video/webm">
  
    <p class="vjs-no-js">
  
      To view this video please enable JavaScript, and consider upgrading to a web browser that <a href="http://videojs.com/html5-video-support/" target="_blank">supports HTML5 video</a>
  
    </p>
  
  </source></source></video>

  This works fine on desktop browsers, where it uses the m4v file. However, if I load the page on an iDevice, the video player says "no compatible source was found for this video", which sounds like it doesn’t like either the m4v or the webm file.

  I created the webm file using instructions found at http://daniemon.com/blog/how-to-convert-videos-to-webm-with-ffmpeg/. I tried creating a .mov file using the accepted answer at iPad Doesn’t Render H.264 Video with HTML5, but this gave the same error.

  Anyone any ideas how I can support iDevices ? Please don’t blind me with science, I’m a real newbie with all this video stuff, and need simple instructions !

  Edit The problem I was having was when trying to view the site on a mobile simulator. When I uploaded the site to a real server, and tried it on an iPad, it worked fine. So, if anyone is having a similar problem, first use something like Handbrake to encode the videos, as it seems to do it fine, then make sure you’re testing on a real mobile device, not a simulator !