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• Generating all P frame intra refresh H264 with x264

  3 février 2021, par Andrew

  I am trying to generate a periodic intra refresh h264 stream with only P frames using ffmpeg and x264 but I always get an I frame at the start.

  


  Is there a way with x264 to create a P frame only stream ?

  


  Commands I am using :

  


  ffmpeg -f lavfi -re -i testsrc=duration=5:size=1920x1080:rate=30000/1001 -s 1920x1080 -pix_fmt yuv420p -f rawvideo out.yuv
x264 --input-res 1920x1080 --intra-refresh out.yuv --b-pyramid none -b 0 --ref 0  -o out.264


  


  Verification :

  


      ffprobe -show_frames out.264 |grep pict_type=I


  


  Or just looking at the x264 output e.g.

  


  yuv [info]: 1920x1080p 0:0 @ 25/1 fps (cfr)
x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
x264 [info]: profile High, level 4.0, 4:2:0, 8-bit
x264 [info]: frame I:1     Avg QP:13.63  size: 12189
x264 [info]: frame P:149   Avg QP:13.59  size:   874
x264 [info]: mb I  I16..4: 78.7% 18.6%  2.7%
x264 [info]: mb P  I16..4:  2.3%  0.1%  0.0%  P16..4:  3.2%  0.3%  0.0%  0.0%  0.0%    skip:94.1%
x264 [info]: 8x8 transform intra:7.6% inter:91.5%
x264 [info]: coded y,uvDC,uvAC intra: 1.3% 18.9% 3.6% inter: 0.1% 1.1% 0.1%
x264 [info]: i16 v,h,dc,p: 86%  6%  1%  7%
x264 [info]: i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 42% 22% 36%  0%  0%  0%  0%  0%  0%
x264 [info]: i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 29% 30% 32%  3%  1%  3%  0%  3%  0%
x264 [info]: i8c dc,h,v,p: 28%  7% 55%  9%
x264 [info]: Weighted P-Frames: Y:0.0% UV:0.0%
x264 [info]: kb/s:189.96

encoded 150 frames, 66.76 fps, 189.96 kb/s


  


• x264 encoding frame rate limit

  30 septembre 2014, par James

  I’m using the following parameters to encode a .mp4 video using the x264 lib :

  int fps = 30;
  
  x264_param_default_preset(&x.params, "ultrafast", "stillimage,zerolatency");
  
  x.params.i_threads = 1;
  
  x.params.i_fps_num = fps;
  
  x.params.i_fps_den = 1;
  
  x.params.i_timebase_num = 1;
  
  x.params.i_timebase_den = fps;

  If I set fps to be equal to 25 or less the video encodes in the correct frame rate, however if I try to encode over 25 fps, the frame rate is reduced to 25 fps.

  here is a log output, note there are two videos being encoded at the same time :

  x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  x264 [info]: profile Constrained Baseline, level 4.0
  
  x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  x264 [info]: profile Constrained Baseline, level 4.0
  
  x264 [info]: frame I:2     Avg QP:20.50  size:401756
  
  x264 [info]: frame P:318   Avg QP:24.04  size: 87631
  
  x264 [info]: mb I  I16..4: 100.0%  0.0%  0.0%
  
  x264 [info]: mb P  I16..4:  2.5%  0.0%  0.0%  P16..4: 73.3%  0.0%  0.0%  0.0%  0.0%    skip:24.2%
  
  x264 [info]: coded y,uvDC,uvAC intra: 50.6% 59.2% 15.8% inter: 40.1% 21.6% 0.2%
  
  x264 [info]: i16 v,h,dc,p: 14% 34% 40% 12%
  
  x264 [info]: i8c dc,h,v,p: 39% 28% 19% 13%
  
  x264 [info]: kb/s:21502.55
  
  x264 [info]: frame I:2     Avg QP:20.50  size:380898
  
  x264 [info]: frame P:318   Avg QP:24.01  size: 82754
  
  x264 [info]: mb I  I16..4: 100.0%  0.0%  0.0%
  
  x264 [info]: mb P  I16..4:  2.5%  0.0%  0.0%  P16..4: 73.1%  0.0%  0.0%  0.0%  0.0%    skip:24.4%
  
  x264 [info]: coded y,uvDC,uvAC intra: 50.0% 56.0% 14.9% inter: 38.4% 21.8% 0.2%
  
  x264 [info]: i16 v,h,dc,p: 14% 34% 40% 12%
  
  x264 [info]: i8c dc,h,v,p: 39% 29% 19% 13%
  
  x264 [info]: kb/s:20308.27

• How to make words in ASS subtitles appear one at a time ?

  21 septembre 2022, par ThaDon

  I am trying to burn subtitles into a video such that they appear in a word-by-word fashion instead of all at once.

  



  What I mean by this is, a word will appear, then another word will appear next to it, and so on. Eventually the line will clear, then repeat.

  



  Example :

  



  

  



  I thought I could create an Advanced Substation Alpha file where subtitles share the same end-time but differing start times, however FFMPEG doesn't seem to cope very well when rendering the file :

  



  [Script Info]
; Script generated by FFmpeg/Lavc57.107.100
ScriptType: v4.00+
PlayResX: 384
PlayResY: 288

[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,16,&Hffffff,&Hffffff,&H0,&H0,0,0,0,0,100,100,0,0,1,1,0,2,10,10,10,0

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:03.46,Default,,0,0,0,,I'm
Dialogue: 0,0:00:01.00,0:00:03.46,Default,,0,0,0,,a
Dialogue: 0,0:00:01.50,0:00:03.46,Default,,0,0,0,,subtitle


  



  The idea being that I'm would appear, then 1 second later a would show up next to it followed by subtitle a half second later