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• Preserving or syncing audio of original video to video fragments

  2 mai 2015, par Code_Ed_Student

  I currently have a few videos that I want to split into EXACTLY 30 seconds segments. I have been able to accomplish but the audio is not being properly preserve. Its out of sync. I tried playing arsample ab and other libraries but I am not getting the desired outuput. What would be the best way to both split the videos in exactly 30 second frames and preserve the audio ?

  ffmpeg -i $file -preset medium -map 0 -segment_time 30 -g 225 -r 25  -sc_threshold 0 -force_key_frames expr:gte(t,n_forced*30) -f segment -movflags faststart -vf scale=-1:720,format=yuv420p -vcodec libx264 -crf 20 -codec:a copy $dir/$video_file-%03d.mp4

  short snippet of output

  Input #0, flv, from '/media/sf_linux_sandbox/hashtag_pull/video-downloads/5b64d7ab-a669-4016-b55e-fe4720cbd843/5b64d7ab-a669-4016-b55e-fe4720cbd843.flv':
  
    Metadata:
  
      moovPosition    : 40
  
      avcprofile      : 77
  
      avclevel        : 31
  
      aacaot          : 2
  
      videoframerate  : 30
  
      audiochannels   : 2
  
      ©too           : Lavf56.15.102
  
      length          : 7334912
  
      sampletype      : mp4a
  
      timescale       : 48000
  
    Duration: 00:02:32.84, start: 0.000000, bitrate: 2690 kb/s
  
      Stream #0:0: Video: h264 (Main), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 30.30 fps, 29.97 tbr, 1k tbn, 59.94 tbc
  
      Stream #0:1: Audio: aac (LC), 48000 Hz, stereo, fltp
  
  [libx264 @ 0x3663ba0] using SAR=1/1
  
  [libx264 @ 0x3663ba0] using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64
  
  [libx264 @ 0x3663ba0] profile High, level 3.1
  
  [libx264 @ 0x3663ba0] 264 - core 144 r2 40bb568 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - 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=3 lookahead_threads=1 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=225 keyint_min=22 scenecut=0 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=20.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, segment, to '/media/sf_linux_sandbox/hashtag_pull/video-edits/30/5b64d7ab-a669-4016-b55e-fe4720cbd843/5b64d7ab-a669-4016-b55e-fe4720cbd843-%03d.mp4':
  
    Metadata:
  
      moovPosition    : 40
  
      avcprofile      : 77
  
      avclevel        : 31
  
      aacaot          : 2
  
      videoframerate  : 30
  
      audiochannels   : 2
  
      ©too           : Lavf56.15.102
  
      length          : 7334912
  
      sampletype      : mp4a
  
      timescale       : 48000
  
      encoder         : Lavf56.16.102
  
      Stream #0:0: Video: h264 (libx264), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 25 fps, 12800 tbn, 25 tbc
  
      Metadata:
  
        encoder         : Lavc56.19.100 libx264
  
      Stream #0:1: Audio: aac, 48000 Hz, stereo
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  
    Stream #0:1 -> #0:1 (copy)

• FFMPEG "Segmentation fault" with network stream source

  23 décembre 2023, par user11186466

  I use release : 4.2.2 (static) from "https://johnvansickle.com/ffmpeg/"

  



  Final code will be on "Amazon AWS lambda"

  



  Goal : use a url stream and add watermak

  



  Link to video : ​https://feoval.fr/519.mp4

  



  Link to Watermak : ​https://feoval.fr/watermark.png

  



  ./ffmpeg -i "https://feoval.fr/519.mp4" -i "./watermark.png" -filter_complex "overlay=W-w-10:H-h-10:format=rgb" -f "mp4" -movflags "frag_keyframe+empty_moov" -pix_fmt "yuv420p" test.mp4


  



  return "Segmentation fault"

  



  I have the same error on my computer and on AWS Lambda server

  



  ./ffmpeg -i "https://feoval.fr/519.mp4" -f "mp4" -movflags "frag_keyframe+empty_moov" -pix_fmt "yuv420p" test.mp4


  



  work (but not watermak)

  



  ./ffmpeg -i "./519.mp4" -i "./watermark.png" -filter_complex "overlay=W-w-10:H-h-10:format=rgb" -f "mp4" -movflags "frag_keyframe+empty_moov" -pix_fmt "yuv420p" test.mp4


  



  work (but not with stream)

  



  Thanks you very much !

  



  Logs for the first case who return "Segmentation fault" :

  



  ...
Stream mapping:
Stream #0:0 (h264) -> overlay:main (graph 0)
Stream #1:0 (png) -> overlay:overlay (graph 0)
overlay (graph 0) -> Stream #0:0 (libx264)
Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, ? for help
[libx264 @ 0x742e480] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0x742e480] profile High, level 3.1, 4:2:0, 8-bit
[libx264 @ 0x742e480] 264 - core 159 r2991 1771b55 - H.264/MPEG-4 AVC codec - Copyleft 2003-2019 - ​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=25 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 'test.mp4':
Metadata:
major_brand : mp42
minor_version : 1
compatible_brands: isommp41mp42
encoder : Lavf58.29.100
Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 480x848, q=-1--1, 30 fps, 15360 tbn, 30 tbc (default)
Metadata:
encoder : Lavc58.54.100 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)
Metadata:
creation_time : 2020-01-13T08:54:26.000000Z
handler_name : Core Media Audio
encoder : Lavc58.54.100 aac
Segmentation fault (core dumped)


  


• ffmpeg, /dev/video0, -f decklink

  20 mars 2019, par Camille Goudeseune

  I’m trying to capture video from a PCI card, the Blackmagic DeckLink Mini Recorder, via ffmpeg, on a headless host running Ubuntu 18.04.2 LTS, hopefully with a command like

  ffmpeg -f decklink -i /dev/video0 ...

  How can I make that work ? I have two obstacles.

  No /dev/video0

  ffmpeg -i /dev/video0 ... fails : /dev/video0: No such device or address.
  v4l2-ctl --list-devices fails with the same error message.

  I built /dev/video0, and it looks okay :

  mknod /dev/video0 c 81 0
  
  chown root.video /dev/video0
  
  chmod g+rw /dev/video0

  To compare this file with a working one, I ran strace cat /dev/video0 on this host, and on another host (Ubuntu 14) with a working /dev/video0. The outputs began to differ here (good, then bad) :

  fstat(1, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
  
  open("/dev/video0", O_RDONLY)           = 3  
  
  fstat(3, {st_mode=S_IFCHR|0660, st_rdev=makedev(81, 0), ...}) = 0
  
  fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
  
  ----
  
  
  
  fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0
  
  openat(AT_FDCWD, "/dev/video0", O_RDONLY) = -1 ENXIO (No such device or address)

  So /dev/video0 is broken at a level lower than ffmpeg or v4l2 or even cat.

  On Ubuntu 14, man 8 MAKEDEV suggests that the error message means that "the kernel does not have the driver configured or loaded."

  This Ubuntu 18 host lacks that manpage, but it does have a few /snap/core/*/sbin/MAKEDEV, all the same, so I tried

  /snap/core/6350/sbin/MAKEDEV -n -v video

  It would have created over a hundred devices videoXX, radioXX, vtxXX, vbiXX. Those devices didn’t exist yet, so it seemed harmless to try it.

  rm /dev/video0; /snap/core/6350/sbin/MAKEDEV video

  That rebuilt /dev/video0, but "No such device" remains, from cat or ffmpeg.

  No decklink

  ffmpeg -f decklink ... fails with Unknown input format: 'decklink'.

  Neither black nor deck nor link is mentioned by ffmpeg -devices (fbdev, lavfi, oss, v4l2) and ffmpeg -formats (about 350), either for Ubuntu’s own version 3.4.4-0ubuntu0.18.04.1, or for version N-93330-g7ff89574c7 compiled from source on 2019 Mar 13 :

  git clone https://git.ffmpeg.org/ffmpeg.git ffmpeg
  
  cd ffmpeg
  
  ./configure --enable-nonfree --disable-doc --disable-w32threads --enable-pthreads

  (Although ./configure --help mentions --enable-decklink, using that yielded "ERROR : DeckLinkAPI.h not found." updatedb && locate DeckLinkAPI.h finds no file with that name, either.)

  The DeckLink PCI card is recognized by hwinfo and lspci.

  lsmod reports the loaded modules blackmagic and blackmagic_io.

  Maybe the PCI card is installed ok, but ffmpeg just can’t reach it because I can’t configure it for that.

  Edit : Rebooting didn’t fix anything.