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• FFMpeg adding silence : struggling to use -i anullsrc option

  20 août 2020, par Kod4krome

  I am just trying to add a silent audio track to a video file using ffmpeg :

  



  ffmpeg.exe -i video.mkv -i anullsrc -c:v copy -c:a aac -shortest test.mkv


  



  I have ffmpeg precompiled release for windows 64bit (20170208)

  



  Whenever I run I get this error :

  



  anullsrc: No such file or directory


  



  Thanks for any help.

  


• Pipe opencv frames into ffmpeg

  25 juin 2023, par Dmytro Soltusyuk

  I am trying to pipe opencv frames into ffmpeg, but it does not work.

  


  After the research, I found this answer (https://stackoverflow.com/a/62807083/10676682) to work the best for me, so I have the following :

  


  def start_streaming_process(rtmp_url, width, height, fps):
    # fmt: off
    cmd = ['ffmpeg',
           '-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',
           '-flvflags', 'no_duration_filesize',
           rtmp_url]
    # fmt: on

    return subprocess.Popen(cmd, stdin=subprocess.PIPE)


  


  def main():
    width, height, fps = get_video_size(SOURCE_VIDEO_PATH)
    streaming_process = start_streaming_process(
        TARGET_VIDEO_PATH,
        width,
        height,
        fps,
    )

    model = load_yolo(WEIGHTS_PATH)
    frame_iterator = read_frames(video_source=SOURCE_VIDEO_PATH)
    processed_frames_iterator = process_frames(
        model, frame_iterator, ball_target_area=400
    )

    for processed_frame in processed_frames_iterator:
        streaming_process.communicate(processed_frame.tobytes())

    streaming_process.kill()


  


  processed_frame here is an annotated OpenCV frame.

  


  However, after I do my first streaming_process.communicate call, the ffmpeg process exits with code 0 (meaning everything was ok), but it is not. I can not feed the rest of the frames into ffmpeg, because the process exited.

  


  Here are the logs :

  


  Input #0, rawvideo, from 'fd:':
  Duration: N/A, start: 0.000000, bitrate: 663552 kb/s
  Stream #0:0: Video: rawvideo (BGR[24] / 0x18524742), bgr24, 1280x720, 663552 kb/s, 30 tbr, 30 tbn
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
[libx264 @ 0x132e05570] using cpu capabilities: ARMv8 NEON
[libx264 @ 0x132e05570] profile High, level 3.1, 4:2:0, 8-bit
[libx264 @ 0x132e05570] 264 - core 164 r3095 baee400 - H.264/MPEG-4 AVC codec - Copyleft 2003-2022 - h
ttp://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=15 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 inter
laced=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 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbt
ree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, flv, to 'rtmp://global-live.mux.com:5222/app/9428e064-e5d3-0bee-dc67-974ba53ce164':
  Metadata:
    encoder         : Lavf60.3.100
  Stream #0:0: Video: h264 ([7][0][0][0] / 0x0007), yuv420p(tv, progressive), 1280x720, q=2-31, 30 fps
, 1k tbn
    Metadata:
      encoder         : Lavc60.3.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame=    1 fps=0.0 q=29.0 Lsize=      41kB time=00:00:00.00 bitrate=N/A speed=   0x    eed=N/A    
video:40kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.678311%
[libx264 @ 0x132e05570] frame I:1     Avg QP:25.22  size: 40589
[libx264 @ 0x132e05570] mb I  I16..4: 37.7% 33.4% 28.9%
[libx264 @ 0x132e05570] 8x8 transform intra:33.4%
[libx264 @ 0x132e05570] coded y,uvDC,uvAC intra: 51.1% 53.2% 14.4%
[libx264 @ 0x132e05570] i16 v,h,dc,p: 32% 38% 20% 10%
[libx264 @ 0x132e05570] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 16% 36% 28%  3%  2%  2%  3%  3%  6%
[libx264 @ 0x132e05570] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 18% 37% 17%  4%  4%  4%  5%  4%  7%
[libx264 @ 0x132e05570] i8c dc,h,v,p: 46% 37% 12%  4%
[libx264 @ 0x132e05570] kb/s:9741.36


  


  That's all. Exit code 0.

  


• FFmpeg inaccurate outputs [duplicate]

  20 mai 2020, par Shlomi

  


  Possible Duplicate :
  
 ffmpeg : videos before and after conversion aren’t the same length

  


  





  Recently, I've been trying to use FFmpeg for an application which requires a VERY accurate manipulation when it comes to the time parameter (milliseconds resolution). Unfortunately, I was surprised to find out that FFmpeg's manipulation functionalities return some inaccurate results.

  



  Here is the output of 'ffmpeg' :

  



  ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
  built on Jul 25 2012 19:55:05 with gcc 4.2.1 (Apple Inc. build 5664)
  configuration: --enable-gpl --enable-shared --enable-pthreads --enable-libx264 --enable-libmp3lame
  libavutil      51. 54.100 / 51. 54.100
  libavcodec     54. 23.100 / 54. 23.100
  libavformat    54.  6.100 / 54.  6.100
  libavdevice    54.  0.100 / 54.  0.100
  libavfilter     2. 77.100 /  2. 77.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100


  



  Now, let's assume I want to rip the audio track of 'foo.mov'. Here is the relevant output of 'ffmpeg -i foo.mov' :

  



  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'foo.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 0
    compatible_brands: qt  
    creation_time   : 2012-07-24 23:16:08
  Duration: 00:00:40.38, start: 0.000000, bitrate: 805 kb/s
    Stream #0:0(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 480x360, 733 kb/s, 24.46 fps, 29.97 tbr, 600 tbn, 1200 tbc
    Metadata:
      rotate          : 90
      creation_time   : 2012-07-24 23:16:08
      handler_name    : Core Media Data Handler
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, s16, 63 kb/s
    Metadata:
      creation_time   : 2012-07-24 23:16:08
      handler_name    : Core Media Data Handler


  



  As you probably noticed, the video file duration is 00:00:40.38. Using the following command, I ripped it's audio track :

  



  'ffmpeg -i foo.mov foo.wav'

  



  Output :

  



  Output #0, wav, to 'foo.wav':
  Metadata:
    major_brand     : qt  
    minor_version   : 0
    compatible_brands: qt  
    creation_time   : 2012-07-24 23:16:08
    encoder         : Lavf54.6.100
    Stream #0:0(und): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, mono, s16, 705 kb/s
    Metadata:
      creation_time   : 2012-07-24 23:16:08
      handler_name    : Core Media Data Handler
Stream mapping:
  Stream #0:1 -> #0:0 (aac -> pcm_s16le)
Press [q] to stop, [?] for help
size=3482kB time=00:00:40.42 bitrate= 705.6kbits/s    
video:0kB audio:3482kB global headers:0kB muxing overhead 0.001290%


  



  As you can see, the output file is longer than the file in the input.

  



  Another example is audio (and video) file trimming :
Let's assume I would like to use ffmpeg for audio file trimming. I used the next command :

  



  'ffmpeg -t 00:00:10.000 -i foo.wav trimmed_foo.wav -ss 00:00:25.000'

  



  Output :

  



  [wav @ 0x10180e800] max_analyze_duration 5000000 reached at 5015510
Guessed Channel Layout for  Input Stream #0.0 : mono
Input #0, wav, from 'foo.wav':
  Duration: 00:00:40.42, bitrate: 705 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, mono, s16, 705 kb/s
Output #0, wav, to 'trimmed_foo.wav':
  Metadata:
    encoder         : Lavf54.6.100
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, mono, s16, 705 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le -> pcm_s16le)
    Press [q] to stop, [?] for help
size=864kB time=00:00:10.03 bitrate= 705.6kbits/s    
video:0kB audio:864kB global headers:0kB muxing overhead 0.005199%


  



  Again, the output file is 30 milliseconds longer than I expected.

  



  I tried, for a long time, to research the issue without any success. When I use audacity for the same functionality, it does it very accurately !

  



  Does anyone have any idea how to solve this problem ?