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• ffmpeg weird x264 encoding behavior

  1er février 2016, par JMor

  I have a captured a 720x480 video with a display aspect ratio of 16:9 which I want to crop, resize and pad, but just the x264 encoding command is giving me a headache.

  (Screenshot of input.m2v) Here is my command :

  ffmpeg -ss 1861 -i input.m2v -c:v libx264 -profile:v main -preset:v medium -level 3.1 -x264opts crf=21.228 -t 60 -y -f mp4 output.mp4

  And here is the ffmpeg output :

  (Screen shot of output.mp4)

  Input #0, mpegvideo, from 'input.m2v':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: mpeg2video (Main), yuv420p(tv), 720x480 [SAR 32:27 DAR 1
  
  6:9], max. 6605 kb/s, 31.02 fps, 59.94 tbr, 1200k tbn, 59.94 tbc
  
  [libx264 @ 02ba84c0] using SAR=32/27
  
  [libx264 @ 02ba84c0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 02ba84c0] profile Main, level 3.1
  
  [libx264 @ 02ba84c0] 264 - core 144 r2525 40bb568 - H.264/MPEG-4 AVC codec - Cop
  
  yleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deb
  
  lock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 m
  
  e_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chro
  
  ma_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=25 scene
  
  cut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=21.2 qcomp=0.60 qpmin
  
  =0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'output.mp4':
  
    Metadata:
  
      encoder         : Lavf56.19.100
  
      Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 720x48
  
  0 [SAR 32:27 DAR 16:9], q=-1--1, 29.97 fps, 30k tbn, 29.97 tbc
  
      Metadata:
  
        encoder         : Lavc56.21.102 libx264
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mpeg2video (native) -> h264 (libx264))

  The output size is 720x480, displayed as 853x480, as expected.
  But it looks like the frame has been vertically scaled by a factor of 1.18 and then cropped to a height of 480, so that I am losing the top and bottom of the frame. In fact, the behavior is equivalent to :

  -vf "scale=720:569,crop=720:480:0:0"

  Although I assume the aspect ratio plays a part here (I think the 1.18 factor is really (16/9)/(720/480)) I am surprised that ffmpeg would do that out of the blue. May be someone more knowledgeable than me could explain it ?

• ffmpeg weird x264 encoding behavior

  1er février 2016, par JMor

  I have a captured a 720x480 video with a display aspect ratio of 16:9 which I want to crop, resize and pad, but just the x264 encoding command is giving me a headache.

  (Screenshot of input.m2v) Here is my command :

  ffmpeg -ss 1861 -i input.m2v -c:v libx264 -profile:v main -preset:v medium -level 3.1 -x264opts crf=21.228 -t 60 -y -f mp4 output.mp4

  And here is the ffmpeg output :

  (Screen shot of output.mp4)

  Input #0, mpegvideo, from 'input.m2v':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: mpeg2video (Main), yuv420p(tv), 720x480 [SAR 32:27 DAR 1
  
  6:9], max. 6605 kb/s, 31.02 fps, 59.94 tbr, 1200k tbn, 59.94 tbc
  
  [libx264 @ 02ba84c0] using SAR=32/27
  
  [libx264 @ 02ba84c0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 02ba84c0] profile Main, level 3.1
  
  [libx264 @ 02ba84c0] 264 - core 144 r2525 40bb568 - H.264/MPEG-4 AVC codec - Cop
  
  yleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deb
  
  lock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 m
  
  e_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chro
  
  ma_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=25 scene
  
  cut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=21.2 qcomp=0.60 qpmin
  
  =0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'output.mp4':
  
    Metadata:
  
      encoder         : Lavf56.19.100
  
      Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 720x48
  
  0 [SAR 32:27 DAR 16:9], q=-1--1, 29.97 fps, 30k tbn, 29.97 tbc
  
      Metadata:
  
        encoder         : Lavc56.21.102 libx264
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mpeg2video (native) -> h264 (libx264))

  The output size is 720x480, displayed as 853x480, as expected.
  But it looks like the frame has been vertically scaled by a factor of 1.18 and then cropped to a height of 480, so that I am losing the top and bottom of the frame. In fact, the behavior is equivalent to :

  -vf "scale=720:569,crop=720:480:0:0"

  Although I assume the aspect ratio plays a part here (I think the 1.18 factor is really (16/9)/(720/480)) I am surprised that ffmpeg would do that out of the blue. May be someone more knowledgeable than me could explain it ?

• How to add BGM when pipe opencv images to ffmpeg - python

  23 mars 2020, par karobben

  Basically, I know how to stream by Pipe opencv to ffmpeg using python.
  But my problem is I can’t add an audio file (BGM) for it. Does anyone know how to make it with python ?

  my python code is :

  import cv2 as cv
  
  import subprocess as sp
  
  
  
  # ffmpeg command
  
  
  
  command = ['ffmpeg',
  
          #'-re', '-stream_loop', '-1', 
  
          #'-i', '/home/pi/scrpt/Blive/StarBucks_BGN.mp3',
  
          '-y',
  
          '-f', 'rawvideo',
  
          '-vcodec','rawvideo',
  
          '-pix_fmt', 'bgr24',
  
          '-s', "{}x{}".format(width, height),
  
          '-r', str(fps),
  
          '-i', '-',
  
          '-c:v', 'libx264',
  
          '-pix_fmt', 'yuv420p',
  
          '-preset', 'ultrafast',
  
          '-f', 'flv',
  
          rtmpUrl]

  I know that I can achieve this by :

  sudo raspivid -o - -t 0 -w 1280 -h 720 -fps 24 -b 1000000 | 
  
                  ffmpeg  -re -stream_loop -1 -i  "/home/pi/scrpt/Blive/StarBucks_BGN.mp3" \
  
          -f h264 -i - -vcodec copy -r 30 -acodec aac -b:a 100k -preset ultrafast \
  
          -tune zerolatency -f flv "rtmp://"

  So, I tried to add -re -stream_loop -1 -i  "/home/pi/scrpt/Blive/StarBucks_BGN.mp3" into the python pipe, but it crashed with :

  [libx264 @ 0x1952aa0] using cpu capabilities: ARMv6 NEON
  
  [libx264 @ 0x1952aa0] profile Constrained Baseline, level 3.1
  
  [libx264 @ 0x1952aa0] 264 - core 148 r2748 97eaef2 - H.264/MPEG-4 AVC codec - Copyleft 2003-2016 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
  
  [flv @ 0x1951d00] FLV does not support sample rate 48000, choose from (44100, 22050, 11025)
  
  [flv @ 0x1951d00] Audio codec mp3 not compatible with flv
  
  Could not write header for output file #0 (incorrect codec parameters ?): Function not implementedStream mapping:
  
    Stream #1:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  
    Stream #0:0 -> #0:1 (mp3 (native) -> mp3 (libmp3lame))
  
      Last message repeated 1 times
  
  Traceback (most recent call last):
  
    File "With_BG.py", line 57, in <module>
  
      p.stdin.write(BG.tostring())
  
  BrokenPipeError: [Errno 32] Broken pipe
  
  </module>