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• vf_paletteuse : fix color cache lookup for Bayer dithering mode.

  10 janvier 2022, par Rudolf Polzer

  vf_paletteuse : fix color cache lookup for Bayer dithering mode.
  To trigger this bug, use `paletteuse=dither=bayer:bayer_scale=0` ; you will see
  
  that adjacent pixel lines will use the same dither pattern, instead of being
  
  shifted from each other by 32 units (0x20).
  One way to demostrate the bug is :
  $ convert -size 64x256 gradient:black-white -rotate 270 grad.png
  
  $ echo 'P2 2 1 255 0 255' > bw.pnm
  
  $ ffmpeg -i grad.png -filter_complex 'movie=bw.pnm,scale=256x1[bw] ; [0:v][bw]paletteuse=dither=bayer:bayer_scale=0' gradbw.png
  Previously : https://www.rm.cloudns.org/img/uploaded/0bd152c11b9cd99e5945115534b1bdde.png
  
  Now :        https://www.rm.cloudns.org/img/uploaded/89caaa5e36c38bc2c01755b30811f969.png
  This was caused by passing inconsistent color vs (a,r,g,b) parameters to
  
  color_get(), and NBITS being 5 meaning actually hitting the same cache node
  
  does happen in this case, but ONLY if bayer_scale is zero.
  The fix is passing the correct color value to color_get().
  Also added a previous-failing FATE test ; image comparison of the first frame :
  Previously : https://www.rm.cloudns.org/img/uploaded/d0ff9db8d8a7d8a3b8b88bbe92bf5fed.png
  
  Now :        https://www.rm.cloudns.org/img/uploaded/a72389707e719b5cd1c58916a9e79ca8.png
  (on this less synthetic test image, the bug basically causes noise from cache
  
   hits vs misses)
  Tested : FATE passes, which exercises this filter but at the default bayer_scale.
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  

  • [DH] libavfilter/vf_paletteuse.c
  • [DH] tests/fate/filter-video.mak
  • [DH] tests/ref/fate/filter-paletteuse-bayer0

• How to concatenate two MP4 files, which require http basic Authorization : Bearer , using ffmpeg ?

  8 juillet 2023, par Jeff Strongman

  Hello dear ffmpeg experts ! 🧠 🎯

  


  I ran the following command, which worked perfectly :

  


  ffmpeg -protocol_whitelist https,concat,tls,tcp -i "concat :https://dash.akamaized.net/akamai/bbb_30fps/bbb_30fps_1280x720_4000k/bbb_30fps_1280x720_4000k_0.m4v|https://dash.akamaized.net/akamai/bbb_30fps/bbb_30fps_1280x720_4000k/bbb_30fps_1280x720_4000k_1.m4v|https://dash.akamaized.net/akamai/bbb_30fps/bbb_30fps_1280x720_4000k/bbb_30fps_1280x720_4000k_2.m4v" -c:v copy -vframes 180 -y Movie_of_6_seconds.mp4

  


  I followed the recommended solution of the following post :
How to concatenate two MP4 files using FFmpeg ?

  


  You can execute the command on your local computer and see that it should run just fine...

  


  I used 3. concat protocol, which does indeed concat init + progressive segments

  


  However... when every segment on a server I refer to, is password protected, it fails with 401 Unauthorized, even though I added the following line :
-headers "Authorization : Bearer bas64user:password" , before specifying the -i "concat :...".

  


  It seems to me... that the headers don't pass to the concat command inside of the input of ffmpeg... and it simply ignores them. When I used the same -headers command, on a single file, without concat, it passed the authorization successfully

  


  Notes :

  


  

  • Even though every segment has a length of 120 frames (So in maximum, I could have generated 2*120 = 240 frames... I wanted a movie of 6 seconds and not 8... And by this way, to test that ffmpeg is smart enough to stop processing the whole input). To do that, I used -vframes 180, where 180 / 30 (FPS) = 6 seconds

  


  • I used -c:v copy, to get without re-encoding, only the video part (No audio !)

  


  • I used -y to override existing file...

  


  • 0.m4v, is the init file ! it is a small file, that has metadata of the original video which was produced with mpeg-dash

  


  • 1.m4v and 2.m4v, are the progressive segments

  


  


  Is there a way, to pass the http basic headers (Authorization : Bearer) to all of the chained files ?

  


  Like :

  


  

  • Via a json content type on the ffmpeg request

  


  • Or user:password@video_segment (Although... it seems to me it's not a header ?)

  


  • Somehow specify header inside the concat command ?

  


  


  I don't want to first download all files and then get rid of the password protected... as it both takes ridiculous time & other resources... and I would like to record from a segment that is "endless", meaning a camera that keeps streaming data.

  


  Thanks in advance 🙏🏻,

  


  FFmpeg noobie 🙈

  


• Is there an efficient way to retrieve frames from a video in Android ?

  28 mars 2015, par Naveed

  I have an app which requires me to retrieve frames from a video and do some processing with them. However it seems like that the frame retrieval is very slow to the point where it is unacceptable. Sometimes it is taking upto 2.5 second to retrieve a single frame. I am using the MediaMetadataRetriever as most stackoverflow questions suggested. However the performance is very bad. Here is what I have :

     private List<bitmap> retrieveFrames() {
  
  
  
          MediaMetadataRetriever fmmr = new MediaMetadataRetriever();
  
          fmmr.setDataSource("/path/to/some/video.mp4");
  
          String strLength = fmmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
  
          long milliSecs = Long.parseLong(strLength);
  
          long microSecLength = milliSecs * 1000;
  
  
  
          Log.d("TAG", "length: " + microSecLength);
  
          long one_sec = 1000000; // one sec in micro seconds
  
  
  
          ArrayList<bitmap> frames = new ArrayList&lt;>();
  
          int j = 0;
  
          for (int i = 0; i &lt; microSecLength; i += (one_sec / 5)) {
  
              long time = System.currentTimeMillis();
  
              Bitmap frame = fmmr.getFrameAtTime(i, MediaMetadataRetriever.OPTION_CLOSEST);
  
              j++;
  
              Log.d("TAG", "Frame number: " + j + " Time taken: " + (System.currentTimeMillis() - time));
  
              // commented out because each frame would be written to disk instead of holding them in memory
  
              //  frames.add(frame);
  
          }
  
          fmmr.release();
  
          return frames;
  
      }
  
  </bitmap></bitmap>

  The above will logs :

  03-26 21:49:29.781  13213-13239/com.example.naveed.myapplication D/TAG﹕ length: 4949000
  
  03-26 21:49:30.187  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 1 Time taken: 406
  
  03-26 21:49:30.779  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 2 Time taken: 592
  
  03-26 21:49:31.578  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 3 Time taken: 799
  
  03-26 21:49:32.632  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 4 Time taken: 1054
  
  03-26 21:49:33.895  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 5 Time taken: 1262
  
  03-26 21:49:35.382  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 6 Time taken: 1486
  
  03-26 21:49:37.128  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 7 Time taken: 1746
  
  03-26 21:49:39.077  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 8 Time taken: 1948
  
  03-26 21:49:41.287  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 9 Time taken: 2210
  
  03-26 21:49:43.717  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 10 Time taken: 2429
  
  03-26 21:49:44.093  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 11 Time taken: 376
  
  03-26 21:49:44.707  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 12 Time taken: 614
  
  03-26 21:49:45.539  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 13 Time taken: 831
  
  03-26 21:49:46.597  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 14 Time taken: 1057
  
  03-26 21:49:47.875  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 15 Time taken: 1278
  
  03-26 21:49:49.384  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 16 Time taken: 1508
  
  03-26 21:49:51.112  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 17 Time taken: 1728
  
  03-26 21:49:53.096  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 18 Time taken: 1983
  
  03-26 21:49:55.315  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 19 Time taken: 2218
  
  03-26 21:49:57.711  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 20 Time taken: 2396
  
  03-26 21:49:58.065  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 21 Time taken: 354
  
  03-26 21:49:58.640  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 22 Time taken: 574
  
  03-26 21:49:59.369  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 23 Time taken: 728
  
  03-26 21:50:00.112  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 24 Time taken: 742
  
  03-26 21:50:00.834  13213-13239/com.example.naveed.myapplication D/TAG﹕ Frame number: 25 Time taken: 721

  As you can see from above, it is taking about 18 - 25 sec to retrieve 25 frames from a 4 sec long video.

  I have also tried this which uses FFmpeg underneath to do the same. I am not sure how well this library is implemented but it only improves the over all performance by a couple of seconds meaning it takes about 15-20 sec to do the same.

  So my question is : is there a way to do it quicker ? My friend has an iOS app where he does something similar but it only takes couple of seconds and he is grabbing even more frames however he is not sure how to do it on android.

  Is there anything on android that would speed up the process. Am I approaching this wrong ?

  The end goal is to stitch those frames together into a gif.