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• How to add black frames and keep the framerate ?

  3 mars 2020, par Patryk

  I have a black image from which I generate videos filled with black color only for specified lengths that I can then concatenate with my destination videos. This is how I produce it :

  ffmpeg -loop 1 -i black.png -t 00:00:00.066 \ 
  
      -c:v libx264 -pix_fmt yuv420p -vf scale=840:480,fps=15 out66ms.mp4

  with the following ffmpeg output :

  Input #0, png_pipe, from 'black.png':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: png, rgba(pc), 608x342 [SAR 5669:5669 DAR 16:9], 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (png (native) -> h264 (libx264))
  
  Press [q] to stop, [?] for help
  
  [libx264 @ 0x7fadf3826e00] using SAR=64/63
  
  [libx264 @ 0x7fadf3826e00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
  
  [libx264 @ 0x7fadf3826e00] profile High, level 3.0
  
  [libx264 @ 0x7fadf3826e00] 264 - core 155 r2917 0a84d98 - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=15 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'out66ms.mp4':
  
    Metadata:
  
      encoder         : Lavf58.29.100
  
      Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 840x480 [SAR 64:63 DAR 16:9], q=-1--1, 15 fps, 15360 tbn, 15 tbc
  
      Metadata:
  
        encoder         : Lavc58.54.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
  frame=    1 fps=0.0 q=27.0 Lsize=       2kB time=00:00:00.00 bitrate=201107.7kbits/s speed=0.0031x
  
  video:1kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 100.984009%
  
  [libx264 @ 0x7fadf3826e00] frame I:1     Avg QP:12.00  size:   123
  
  [libx264 @ 0x7fadf3826e00] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 0x7fadf3826e00] 8x8 transform intra:0.0%
  
  [libx264 @ 0x7fadf3826e00] coded y,uvDC,uvAC intra: 0.0% 0.0% 0.0%
  
  [libx264 @ 0x7fadf3826e00] i16 v,h,dc,p: 97%  0%  3%  0%
  
  [libx264 @ 0x7fadf3826e00] i8c dc,h,v,p: 100%  0%  0%  0%
  
  [libx264 @ 0x7fadf3826e00] kb/s:14.76

  I’d like to then concatenate it with videos like this one :

  ffprobe file.ts
  
  Input #0, mpegts, from 'file.ts':
  
    Duration: 00:00:06.67, start: 0.000000, bitrate: 1090 kb/s
  
    Program 1
  
      Metadata:
  
        service_name    : Service01
  
        service_provider: FFmpeg
  
      Stream #0:0[0x100]: Video: h264 (Baseline) ([27][0][0][0] / 0x001B), yuv420p(progressive), 864x480, 90k tbr, 90k tbn, 180k tbc

  but as soon as I concatenate it using concat demuxer like that :

  ffmpeg -y -hide_banner \
  
      -f concat -safe 0 \
  
      -i <(echo "file '$PWD/out66ms.mp4'"; for f in dir/*.ts; do echo "file '$PWD/$f'"; done) \
  
      -c copy \
  
      output.mp

  I get this :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf58.29.100
  
    Duration: 00:01:41.38, start: 0.000000, bitrate: 170 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 840x480 [SAR 64:63 DAR 16:9], 170 kb/s, 2.67 fps, 2.67 tbr, 15360 tbn, 30 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler

  Which has 2.67 fps whereas not adding this empty black video to concatenation gives the following (desired 15 fps) :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf58.29.100
  
    Duration: 00:00:17.29, start: 0.000000, bitrate: 1001 kb/s
  
      Stream #0:0(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 864x480, 999 kb/s, 15.62 fps, 15.58 tbr, 90k tbn, 180k tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler

  EDIT

  I’ve tried reencoding instead of copying :

  ffmpeg -y -hide_banner \
  
      -f concat -safe 0 \
  
      -i <(echo "file '$PWD/out66ms.mp4'"; for f in dir/*.ts; do echo "file '$PWD/$f'"; done) \
  
      -c:v libx264 -vf scale=840:480,fps=15 \
  
      output.mp

  But I get a similar result :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf58.29.100
  
    Duration: 00:01:41.00, start: 0.000000, bitrate: 555 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1680x480 [SAR 64:63 DAR 32:9], 554 kb/s, 15 fps, 15 tbr, 15360 tbn, 30 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler

  even though that the fps is set properly the video is too long and slowed down.

  How to properly add those black filled videos to preserve fps or set it to desired value ?

• ffmpeg puts black frames in the first few seconds of the video

  30 juin 2018, par Joe T. Boka

  I am adding an audio file to a video file, using ffmpy, which is a python wrapper for ffmpeg.

  The input audio file voice.wave and the input video file video.avi are the same length.

  When I use the below code, the output video output.ts contains both audio and video, as expected. The problem : the audio is running fine, but the first few seconds of the output video output.ts is black.

  from ffmpy import FFmpeg
  
  ff = FFmpeg(inputs={'video.avi': None, 'voice.wav': None}, outputs={'output.ts': '-c:v h264 -c:a ac3'})
  
  ff.cmd
  
  'ffmpeg  -i voice.wave -i video.avi -c:v h264 -c:a ac3 output.ts'
  
  ff.run()

• ffmpeg video encode add artefacts on very dark scenes (near to black)

  10 juin 2021, par Marco999

  I have many videos ripped from blu ray (h.264).

  


  I don't have sufficient space to store all videos and I like to re-encode all video with hevc codec (h.265) and keep similar quality (not exactly the some) but with a good compromise.

  


  I have tried this command :

  


  ffmpeg.exe -hide_banner -hwaccel nvdec -hwaccel_device 0 -vsync 0 -i "title00.mkv" -c:s copy -an  -c copy -c:v:0 hevc_nvenc -profile:v main10 -pix_fmt p010le  -rc-lookahead 32 -spatial-aq 1 -aq-strength 12  -cq 30 -qmin 1 -qmax 30 -b:v:0 10M -maxrate:v:0 20M -gpu 0  title00_nvidia_no_audio.mkv


  


  the quality is excellent and is very close to original, but on the very dark scenes (near to black) there are visible artefacts.

  


  To solve the problem I have tried this changes without get any improvement :

  


  -cq 25 -qmin 1 -qmax 25 

-spatial-aq 1 -aq-strength 4


  


  For some strange reason seem that if I decrease the -cq from 30 to 25 the artefacts are more visible.

  


  I general I'am satasfied about the quality result but before start the encoding I like to understand if there is a way to reduce/remove these artefacts on very dark scenes.

  


  Any tips ?

  


  Thanks !