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• Grabbing images from mp4 using ffmpeg : How to get image after X seconds

  10 septembre 2015, par Anthony

  I am trying to grab images from an mp4. The video is 241 seconds long and looking at data from VLC player I can see that the Frame rate is 4.

  I would like to grab an image from the video every 5 seconds. Since 241/5 = 48.2 In total I would like to have around 49 images in the end.

  How can I do this ?

  I tried the following simply by trial and error :

  ffmpeg -i ~/inputvideo.mp4 -r 0.4 -t 240 image-%d.png

  This gives me a total of 50 images from the video.

• Crossfade between images in video using ffmpeg in android

  11 septembre 2015, par vishnus

  I have managed to create a video from a series of images using this ffmpeg library ffmpeg-android-java

  My command to generate the video is

  "-y -r 1/3 -i /path/img%d.jpg  +
  
    "-strict experimental -vcodec libx264 -pix_fmt yuv420p -preset ultrafast -t 21 -crf 30 /path/out.mp4"

  In my case each image is shown for 3 seconds in the video and video is made of total 7 images.

  I want to achieve a crossfade effect when the images change in the video.

  If anyone has done this before then please point me in the right direction.

• Generating 64kbps audio-only mpegts for HTTP Live segmenter to meet 64kbps audio only requirement

  14 juin 2013, par Pobre

  I am trying to convert our mp4 files into mpeg-ts and segment it into .ts files for my iphone app to play. I am using Carson McDonalds's HTTP-Live-Video-Stream-Segmenter-and-Distributor to do that.

  I got his stuff complied and working correctly. I am currently trying to meet Apple's requirement where I need to provide a baseline 64 kbps audio only stream to my m3u8 playlist.
  Carson doesn't seem to have a profile for that.

  I need to be able to generate 64kbps audio-only stream from mp4, and turn that into mpeg-ts for the segmenter into ts. I am trying to find the right ffmpeg command that will validate without problem using Apple's mediastreamvalidator.

  So far I modified an existing encoding profile to try to achieve 64kbps total :

  ffmpeg -er 4 -i %s -f mpegts -acodec libmp3lame -ar 22050 -ab 32k -s 240x180 -vcodec libx264 -b 16k -flags +loop+mv4 -cmp 256 -partitions +parti4x4+partp8x8+partb8x8 -subq 7 -trellis 1 -refs 5 -coder 0 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -bt 64k -maxrate 16k -bufsize 16k -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 -level 30 -aspect 4:3 -r 10 -g 30 -async 2 - | %s %s %s %s %s

  but then when I try to validate it using mediastreamvalidator, it gives error after few ts :

  Playlist Validation : OK

  Segments :

  sample_cell_4x3_64k-00001.ts :

  WARNING : Media segment exceeds target duration of 10.00 seconds by 1.30 seconds (segment duration is 11.30 seconds)

  sample_cell_4x3_64k-00002.ts :

  WARNING : Media segment exceeds target duration of 10.00 seconds by 1.40 seconds (segment duration is 11.40 seconds)

  ....
  ....

  sample_cell_4x3_64k-00006.ts :

  ERROR : (-1) Unknown video codec : 1836069494 (program 0, track 0)
  ERROR : (-1) failed to parse segment as either an MPEG-2 TS or an ES

  sample_cell_4x3_64k-00007.ts :

  ERROR : (-1) Unknown video codec : 1836069494 (program 0, track 0)
  ERROR : (-1) failed to parse segment as either an MPEG-2 TS or an ES

  ....
  ....
  Average segment duration : 10.26 seconds
  Average segment bitrate : 376797.92 bps
  Average segment structural overhead : 349242.17 bps (92.69 %)

  Is there someway I can generate this correctly with just audio which totals 64kbps and turn it into mpeg-ts ready to be segmented and validated correctly ?

  Am I approaching the problem right ?