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• Scenecut detection and consistent GOP size - adaptive streaming

  24 mars 2014, par Tarun

  Sample Command :

  -map 0:0 -f mp4 -vcodec libx264 -preset slow -profile:v main -vf scale="640:trunc(ow/a/2)*2" -vb 700k -minrate 650k -maxrate 750k -bufsize 10000k -an -g 48 -x264opts keyint=48:min-keyint=10:scenecut=40 -flags +cgop -sc_threshold 40 -pix_fmt yuv420p -threads 0 -y

  There is as such no error in encoding, But I wanted to understand following points-

  1) the above command will ensure that range of GOP size is 10,48, and if any scene change value (frame1 to fame2) is >40%, then a keyframe is introduced there ?

  2) So that means in a 3 hours of source video, there is no guarantee that GOP size will remain same

  3) No consider, I am creating 7 MP4 files each with different bitrate and resolution. (These Mp4s will be encoded to smooth in later stage). Hence i am targeting adaptive streaming. But when I did that, I found that if GOP sizes were not consistent across each bitrates. What I mean by this is, for ex : if in Bitrate1 - GOP size is like 10, 20, 48 and so on, in other bitrates it wasnt in the same sequence. I hope my question makes sense.

  So is there a way to ensure that GOP size may vary across one single output. But it should be consistent across each bitrate provided that the source is same ?

  Also for adaptive streaming Is scenecut detection advisable ?

• Add Timestamp to extracted thumbnail's name from a video file

  12 décembre 2013, par Harish Varada

  I have a requirement of generating thumbnails(camera change, slide change, scene change) from a videofile with it's timestamp(pos) included in the generated output thumbnails.

  I used the following command to generate thumbnails :

  ffmpeg -i input.mp4 -vf select="eq(pict_type\,I)" -vsync 0 -an keyframe-%06d.png

  This command works absolutely fine for generating thumbnails (assume 15 thumbnails are generated) with names in sequence like : keyframe-000001.png, keyframe-000002.png, .... , keyframe-000015.png.

  But, according to my requirement, I need the output thumbnail file names something like as follows :

  keyframe-001426.png, keyframe-002769.png, .... , keyframe-014571.png where

  001426 is the position of thumbnail keyframe-000001.png

  002769 is the position of thumbnail keyframe-000002.png

  014571 is the position of thumbnail keyframe-000015.png

  Is there a way to achieve this in a single command.? Please help me out achieving this.

• Extracting Frames form Video in Android [closed]

  2 juillet 2024, par Muhammad Bilal

  I want to extract frames from video and want to change the frames at that point where i extracted the frames.

  


  I have scene apps like Video Status Maker(https://play.google.com/store/apps/details?id=com.krishna.videostatusmaker), Vidify (https://play.google.com/store/apps/details?id=com.beautifullyrical.videomaker). These apps are using template videos. In my view there is a json file behind the video which exactly tells where the frames should be replaced in the video. I checked out the FFmpeg. It is giving me the frames but as i said there must be file which tells where the frames should be replaced. If anyone Knows how this can be done then please guide me. Thanks