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• libx264 fails on HTTP Live Streaming (FFmpeg)

  12 juillet 2016, par shintaroid

  I want to live stream with HTTP Live Streaming, but I have problem with libx264 or maybe something other.

  My hardware and software environment :

  • Macbook Pro
  • VirtualBox with Ubuntu 16.04
  • Nginx and FFmpeg (in Ubuntu)

  I am able to stream a static video file (in Ubuntu with Nginx and FFmpeg).
  The FFmpeg command is as following :

  $ffmpeg -i /my/sample/video.mp4 -codec:v libx264 -f hls /output/file.m3u8

  But when it comes to webcam (live streaming), Mac OS Safari fails to open the stream. I used the following command :

  $ffmpeg -i /dev/video0 -codec:v libx264 -f hls /output/file.m3u8

  I guess it’s the problem of libx264 because when I use mpeg2video encoder, Mac OS Safari indeed can play the stream :

  $ffmpeg -i /dev/video0 -codec:v mpeg2video -f hls /output/file.m3u8

  I know there is a library called video4linux2, should I use video4linux2 for capturing my webcam ? But I don’t know the appropriate FFmpeg command for HTTP Live Streaming (I tried FFserver but there is error something like cannot rename hls)

  anyone shed some light on my problem ?

• ffmpeg intensity histogram adjustment

  30 septembre 2016, par jlarsch

  I am using ffmpeg for background correction of a video and I would like to improve the intensity scaling of the output.

  My gray scale videos have dark moving objects on a light background. In 8 bit pixel intensities, the light background has pixel values around 240, the dark objects have intensities of around 120.

  outside of ffmpeg, I generate a background image by taking the median frame over some number of frames.
  Then, I use ffmpeg to blend/divide each frame by the background image. (I want to use division, not subtraction of the background).
  [there is also some cropping in my ffmpeg command, but it is irrelevant to my question]

  'ffmpeg.exe', '-i', u'inputVideo.avi', '-i', u'bgMed.tif', '-y', '-r', '160', '-filter_complex', "[1:0] setsar=sar=1 [1sared]; [0:0][1sared] blend=all_mode='divide':repeatlast=1,format=gray,split=1 [int1];[int1]crop=1097:1097:12:11:[out1]", '-map', '[out1]', '-c:v', 'libxvid', '-q:v', '5', '-g', '10', u'outputVideo'

  This procedure is basically working but the resulting video frames look too washed out. This is probably expected ? I am guessing ffmpeg does the division and produces an internal float result which it then maps back to an 8 bit output. I would like to stretch the histogram of the result from the division. It would be preferable to stretch before the mapping to 8 bit for a finer dynamic range.

  In my example, I am assuming that the background division produces a result frame that has a value close to 1 for the background, and values close to 0.5 for the dark objects. Then, ffmpeg seems to be mapping the full range 0-1 into 8 bit 0-255. I would like it to map the range 0.5-1 of the division result into the 8 bit range of the output. is this possible somehow ? Or how else can I achieve a similar result ?

• How can low frame rate video be made to look more smooth ?

  14 décembre 2016, par d3pd

  I am trying to clean up a video that was recorded in 2003 in low-light conditions on what was possibly a cameraphone. The video has been cleaned up somewhat (cropped, logos removed and stabilized), but it remains quite jerky, due in large part to its low frame rate. What are some tricks that might clean up the video in this regard ? I feel that I am asking for something a bit like tweening in flash animations, but for pixels, whereby additional frames are generated using nearby frames of the video. Does such a trick exist ? Is there another way to approach this problem ?

  To reproduce the video processing so far, take the following steps :

  # get video
  
  wget http://www.anwarweb.net/saddamdown.wmv
  
  # crop
  
  ffmpeg -i saddamdown.wmv -filter:v "crop=292:221:14:10" -c:a copy saddamdown_crop.wmv
  
  # remove logo 1
  
  ffmpeg -i saddamdown_crop.wmv -vf delogo=x=17:y=77:w=8:h=54 -c:a copy saddamdown_crop_delogo_1.wmv
  
  # remove logo 2
  
  ffmpeg -i saddamdown_crop_delogo_1.wmv -vf delogo=x=190:y=174:w=54:h=8 -c:a copy saddamdown_crop_delogo_1_delogo_2.wmv
  
  # stabilize
  
  ffmpeg -i saddamdown_crop_delogo_1_delogo_2.wmv -vf deshake saddamdown_crop_delogo_1_delogo_2_deshake.wmv

  Note : The video is of the Saddam Hussein execution.