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• ffmpeg - Different number of macroblocks per each frame

  18 juin 2018, par fabridigua

  i am studying the MPEG compression, in particular how are "labeled" the macroblocks with ffmpeg, using the command :

  ffmpeg -debug mb_type -i input.mp4 out.mp4

  From theory, i know that typically a macroblock is a 16x16 (pixels) block.

  So if a frame is e.g. 1920x1080 i suppose that the macroblocks are

  (1920*1080)/(16*16) = 8100

  Now, analysing the ffmpeg report, I’ve seen that for each frame there are many many less macroblocks (labelled with some "characters" indicating their type).

  Can you explain me why this happens ?
  Is a (mine) theory error ?

  I’ve seen that "visualizing" macroblocks with -debug vis_mb_type there some gray blocks.. corresponding to the (macro)blocks not satisfying any criteria ffmpeg is looking for.. maybe in my example for each frame there are

  8100 - #"gray" macroblocks

  Is this possible ? And why ?

• FFmpeg creating multicast with multiple streams from one source (live source)

  1er mai 2018, par Netheme

  Hi :) I’m facing problems when creating multicast with multiple streams from one source (live source). The issue is that the encoding is slower than realtime. That is big issue for me as I’m processing live feed. The exact command and it’s output you can find here :

  Command

  ffmpeg -y -hwaccel cuvid -c:v h264_cuvid -vsync 0 -deint 2 -drop_second_field 1 -surfaces 10 -i 'udp://@239.10.150.2:5004?fifo_size=100000000&bitrate=12000000'  -map i:0xc77 -r:v:0 25 -filter:v:0 fps=25,scale_npp=640:360:format=same:interp_algo=lanczos -aspect:v:0 16:9 -g:v:0 80 -vcodec:v:0 h264_nvenc -b:v:0 400K -minrate:v:0 400k -maxrate:v:0 400k  -map i:0xc77 -r:v:1 25 -filter:v:1 fps=25,scale_npp=720:405:format=same:interp_algo=lanczos -aspect:v:1 16:9 -g:v:1 80 -vcodec:v:1 h264_nvenc -b:v:1 1000K -minrate:v:1 1000k -maxrate:v:1 1000k  -map i:0xc77 -r:v:2 25 -filter:v:2 fps=25,scale_npp=1280:720:format=same:interp_algo=lanczos -aspect:v:2 16:9 -g:v:2 80 -vcodec:v:2 h264_nvenc -b:v:2 2500K -minrate:v:2 2500K -maxrate:v:2 2500K  -map i:0xc77 -r:v:3 25 -filter:v:3 fps=25,scale_npp=1920:1080:format=same:interp_algo=lanczos -aspect:v:3 16:9 -g:v:3 80 -vcodec:v:3 h264_nvenc -b:v:3 4500K -minrate:v:3 4500K -maxrate:v:3 4500K  -map i:0xc7a -ab:a:0 128k -ar:a:0 48k -acodec:a:0 aac -ac:a:0 2  -map i:0xc7b -ab:a:1 128k -ar:a:1 48k -acodec:a:1 aac -ac:a:1 2  -map i:0xc7c -ab:a:2 128k -ar:a:2 48k -acodec:a:2 aac -ac:a:2 2  -map i:0xc7d -ab:a:3 128k -ar:a:3 48k -acodec:a:3 aac -ac:a:3 2  -f mpegts "udp://@239.100.0.23:3234?overrun_nonfatal_option=1&pkt_size=1316

  And the output (speed should be 1> i hope)

  Stream #0:0 -> #0:0 (h264 (h264_cuvid) -> h264 (h264_nvenc))
  
   Stream #0:0 -> #0:1 (h264 (h264_cuvid) -> h264 (h264_nvenc))
  
   Stream #0:0 -> #0:2 (h264 (h264_cuvid) -> h264 (h264_nvenc))
  
   Stream #0:0 -> #0:3 (h264 (h264_cuvid) -> h264 (h264_nvenc))
  
   Stream #0:1 -> #0:4 (mp2 (native) -> aac (native))
  
   Stream #0:2 -> #0:5 (mp2 (native) -> aac (native))
  
   Stream #0:3 -> #0:6 (mp2 (native) -> aac (native))
  
   Stream #0:4 -> #0:7 (mp2 (native) -> aac (native))
  
  Press [q] to stop, [?] for help
  
  Output #0, mpegts, to 'udp://@239.100.0.23:3234?overrun_nonfatal_option=1&pkt_size=1316':=  -0.0kbits/s speed=N/A    
  
   Metadata:
  
     encoder         : Lavf57.83.100
  
     Stream #0:0: Video: h264 (h264_nvenc) (Main), cuda, 640x360 [SAR 1:1 DAR 16:9], q=-1--1, 400 kb/s, 25 fps, 90k tbn, 25 tbc
  
     Metadata:
  
       encoder         : Lavc57.107.100 h264_nvenc
  
     Side data:
  
       cpb: bitrate max/min/avg: 400000/0/400000 buffer size: 800000 vbv_delay: -1
  
     Stream #0:1: Video: h264 (h264_nvenc) (Main), cuda, 720x405 [SAR 1:1 DAR 16:9], q=-1--1, 1000 kb/s, 25 fps, 90k tbn, 25 tbc
  
     Metadata:
  
       encoder         : Lavc57.107.100 h264_nvenc
  
     Side data:
  
       cpb: bitrate max/min/avg: 1000000/0/1000000 buffer size: 2000000 vbv_delay: -1
  
     Stream #0:2: Video: h264 (h264_nvenc) (Main), cuda, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 2500 kb/s, 25 fps, 90k tbn, 25 tbc
  
     Metadata:
  
       encoder         : Lavc57.107.100 h264_nvenc
  
     Side data:
  
       cpb: bitrate max/min/avg: 2500000/0/2500000 buffer size: 5000000 vbv_delay: -1
  
     Stream #0:3: Video: h264 (h264_nvenc) (Main), cuda, 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 4500 kb/s, 25 fps, 90k tbn, 25 tbc
  
     Metadata:
  
       encoder         : Lavc57.107.100 h264_nvenc
  
     Side data:
  
       cpb: bitrate max/min/avg: 4500000/0/4500000 buffer size: 9000000 vbv_delay: -1
  
     Stream #0:4(cze): Audio: aac (LC), 48000 Hz, stereo, fltp, 128 kb/s
  
     Metadata:
  
       encoder         : Lavc57.107.100 aac
  
     Stream #0:5(eng): Audio: aac (LC), 48000 Hz, stereo, fltp, 128 kb/s
  
     Metadata:
  
       encoder         : Lavc57.107.100 aac
  
     Stream #0:6(hun): Audio: aac (LC), 48000 Hz, stereo, fltp, 128 kb/s
  
     Metadata:
  
       encoder         : Lavc57.107.100 aac
  
     Stream #0:7(ron): Audio: aac (LC), 48000 Hz, stereo, fltp, 128 kb/s
  
     Metadata:
  
       encoder         : Lavc57.107.100 aac
  
  frame= 2868 fps= 19 q=18.0 Lq=14.0 q=15.0 q=16.0 size=  134155kB time=00:01:55.88 bitrate=9484.0kbits/s speed=0.768x

  Does anyone have experiences with something like this ?

• FFmpeg producing a flickering video from images

  21 juin 2018, par jjohnn91

  So I’m trying to make a video of a fractal rotating through some values, much like seen here.

  I generate the frames (1000 of them) using a different program written in Java that works just fine, so for the purposes of this scenario assume that all the images are in the target folder and also in numerical order as they need to appear in the video.

  I found the following code on the web to stitch images into a video, and I haven’t the faintest idea how it works, and when I run it, all of the images are indeed stitched into a video and placed on the desktop, but the video appears to have one specific frame just jump in at random positions. I’m not totally sure which one, but its one of the earlier frames, somewhere between 1 and 200 of the 1000.

  I’ve also tested making two half videos, one using the first 500 frames, and the other using the second 500 frames. The first video (1 -> 500) has flickering, and the second video (501 -> 1000) appears not to have flickering to my observations.

  I am seeking help in fixing the flickering behavior, and I will upload the video file to google drive later if asked. The Images are all 1920x1080, and in proper numerical order.

  Thanks in advance !

  import static org.bytedeco.javacpp.opencv_imgcodecs.*;
  
  import java.io.File; 
  
  import org.bytedeco.javacpp.avcodec;
  
  import org.bytedeco.javacv.FFmpegFrameRecorder;
  
  import org.bytedeco.javacv.OpenCVFrameConverter;
  
  public class ImageToMovie{
  
      public static void main(String []args){
  
          String imgPath="C:\\Users\\John\\Images";
  
          String vidPath="C:\\Users\\John\\Desktop\\video.mp4";
  
          String[] links=new String[new File(imgPath).listFiles().length];
  
          File f=new File(imgPath);
  
          File[] f2=f.listFiles();
  
          for(int i=0;icode>