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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 ?

• 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 ?