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• avformat/flvenc : Avoid unnecessary seek

  16 janvier 2020, par Andreas Rheinhardt

  avformat/flvenc : Avoid unnecessary seek
  When shifting the already written data in order to write the keyframe
  
  index, the flv muxer would first store the pre-shift size, then
  
  calculate how big the index will be eventually, then perform some seeks
  
  to update some size fields, then seek back to the end of the file to get
  
  the new position, followed by a seek to the position where writing will
  
  really start. Seeking back to the (already known) end position (that is
  
  actually used to perform this seek) to get the end position is of course
  
  unnecessary. It has been removed.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/flvenc.c

• Store a videostream from webcam but as 1s long files that can later be merged together [duplicate]

  17 février 2018, par Jennifer R

  This question is an exact duplicate of :

  • How to segment a video and then concatenate back into original one with ffmpeg
    
    1 answer
    

  I’m trying to store a videostream from a webcam but need it to be 1s long files. I have never worked with storing videofiles so i’m not sure if and how i should use opencv and how those videofiles need to be contained that i can merge them together. I tried the old windows cmd code

  copy /b *.avi combined.avi

  but since avi is sort of a container type i only got as far as the first file. I’m guessing since there’s some container data limiting the first file and i can’t watch it.

  I need help in both questions. How can i store a video stream and how do i merge those videos ? Do i use ffmpeg for the latter and is it possible to edit the container data to the correct length ?

• ffmpeg hangs when running -i in alpine docker container cron job

  14 mai 2021, par Richard Westby-Nunn

  I'm see strange behaviour in ffmpeg not running the -i option ONLY when running as a cron job. I can run the command fine directly via the shell. The the cronjob command runs, and it even "starts" the ffmpeg "executable", but it then hangs when it gets to the -i option and arguments.

  


  I have included a copy of a working output when run from the shell prompt to demonstrate what the output should show.

  


  alpine : 3.13.5

  


  docker image : alpine:latest (date : 2021-05-14)

  


  docker run :

  


  docker run -v s:\_docker\_alpine-test:/media/pi --name alpine -it alpine crond -f -l8

  


  crontab script :

  


  /media/pi/_site/pics-alpine.sh 2>&1 | tee /media/pi/_site/alpine.log

  


  /media/pi/_site/pics-alpine.sh script :

  


  #!/bin/ash

set -xv

echo "START"

#encode jpgs to mp4
/usr/bin/ffmpeg -i /media/pi/to-video-back/%04d.jpg  /media/pi/_site/back/back-latest.mp4

echo "END"


  


  The output of the log file is :

  


  echo "START"
+ echo START
START

### encode jpgs to mp4
/usr/bin/ffmpeg -i /media/pi/to-video-back/%04d.jpg  /media/pi/_site/back/back-latest.mp4
+ /usr/bin/ffmpeg -i '/media/pi/to-video-back/%04d.jpg' /media/pi/_site/back/back-latest.mp4
ffmpeg version 4.4 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 10.2.1 (Alpine 10.2.1_git20210328) 20210328
  configuration: --prefix=/usr --enable-avresample --enable-avfilter --enable-gnutls --enable-gpl --enable-libass --enable-libmp3lame --enable-libvorbis --enable-libvpx --enable-libxvid --enable-libx264 --enable-libx265 --enable-libtheora --enable-libv4l2 --enable-libdav1d --enable-postproc --enable-pic --enable-pthreads --enable-shared --enable-libxcb --enable-libsrt --enable-libssh --enable-libvidstab --disable-stripping --disable-static --disable-librtmp --enable-vaapi --enable-vdpau --enable-libopus --enable-vulkan --enable-libsoxr --enable-libwebp --enable-libaom --disable-debug


  


  Script output when run directly from the shell prompt :

  


  /media/pi/_site # ./pics-alpine.sh

echo "START"
+ echo START
START

### encode jpgs to mp4
/usr/bin/ffmpeg -i /media/pi/to-video-back/%04d.jpg  /media/pi/_site/back/back-latest.mp4
+ /usr/bin/ffmpeg -i '/media/pi/to-video-back/%04d.jpg' /media/pi/_site/back/back-latest.mp4
ffmpeg version 4.4 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 10.2.1 (Alpine 10.2.1_git20210328) 20210328
  configuration: --prefix=/usr --enable-avresample --enable-avfilter --enable-gnutls --enable-gpl --enable-libass --enable-libmp3lame --enable-libvorbis --enable-libvpx --enable-libxvid --enable-libx264 --enable-libx265 --enable-libtheora --enable-libv4l2 --enable-libdav1d --enable-postproc --enable-pic --enable-pthreads --enable-shared --enable-libxcb --enable-libsrt --enable-libssh --enable-libvidstab --disable-stripping --disable-static --disable-librtmp --enable-vaapi --enable-vdpau --enable-libopus --enable-vulkan --enable-libsoxr --enable-libwebp --enable-libaom --disable-debug
  libavutil      56. 70.100 / 56. 70.100
  libavcodec     58.134.100 / 58.134.100
  libavformat    58. 76.100 / 58. 76.100
  libavdevice    58. 13.100 / 58. 13.100
  libavfilter     7.110.100 /  7.110.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  9.100 /  5.  9.100
  libswresample   3.  9.100 /  3.  9.100
  libpostproc    55.  9.100 / 55.  9.100
Input #0, image2, from '/media/pi/to-video-back/%04d.jpg':
  Duration: 00:00:00.96, start: 0.000000, bitrate: N/A
  Stream #0:0: Video: mjpeg (Baseline), yuvj420p(pc, bt470bg/unknown/unknown), 1280x960, 25 fps, 25 tbr, 25 tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 0x7fd9cf099b00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x7fd9cf099b00] profile High, level 3.2, 4:2:0, 8-bit
[libx264 @ 0x7fd9cf099b00] 264 - core 161 - H.264/MPEG-4 AVC codec - Copyleft 2003-2021 - 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 '/media/pi/_site/back/back-latest.mp4':
  Metadata:
    encoder         : Lavf58.76.100
  Stream #0:0: Video: h264 (avc1 / 0x31637661), yuvj420p(pc, bt470bg/unknown/unknown, progressive), 1280x960, q=2-31, 25 fps, 12800 tbn
    Metadata:
      encoder         : Lavc58.134.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame=   24 fps=0.0 q=-1.0 Lsize=      25kB time=00:00:00.84 bitrate= 242.1kbits/s speed=1.56x
video:24kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 4.565835%
[libx264 @ 0x7fd9cf099b00] frame I:2     Avg QP:17.30  size:  3693
[libx264 @ 0x7fd9cf099b00] frame P:11    Avg QP:20.46  size:   854
[libx264 @ 0x7fd9cf099b00] frame B:11    Avg QP:22.05  size:   623
[libx264 @ 0x7fd9cf099b00] consecutive B-frames: 29.2% 25.0% 12.5% 33.3%
[libx264 @ 0x7fd9cf099b00] mb I  I16..4: 14.6% 83.5%  2.0%
[libx264 @ 0x7fd9cf099b00] mb P  I16..4:  3.0%  2.2%  0.0%  P16..4:  5.2%  0.1%  0.1%  0.0%  0.0%    skip:89.3%
[libx264 @ 0x7fd9cf099b00] mb B  I16..4:  0.4%  0.1%  0.0%  B16..8:  6.5%  0.0%  0.0%  direct: 0.1%  skip:92.9%  L0:35.0% L1:64.8% BI: 0.2%
[libx264 @ 0x7fd9cf099b00] 8x8 transform intra:73.3% inter:94.3%
[libx264 @ 0x7fd9cf099b00] coded y,uvDC,uvAC intra: 8.5% 12.1% 0.5% inter: 0.7% 3.3% 0.0%
[libx264 @ 0x7fd9cf099b00] i16 v,h,dc,p: 77% 15%  6%  2%
[libx264 @ 0x7fd9cf099b00] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 71%  6% 20%  1%  1%  0%  1%  0%  0%
[libx264 @ 0x7fd9cf099b00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 55% 13% 24%  1%  3%  1%  1%  1%  1%
[libx264 @ 0x7fd9cf099b00] i8c dc,h,v,p: 92%  4%  4%  0%
[libx264 @ 0x7fd9cf099b00] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x7fd9cf099b00] ref P L0: 57.6%  2.5% 30.8%  9.1%
[libx264 @ 0x7fd9cf099b00] ref B L0: 70.2% 27.6%  2.2%
[libx264 @ 0x7fd9cf099b00] ref B L1: 98.5%  1.5%
[libx264 @ 0x7fd9cf099b00] kb/s:196.96

echo "END"
+ echo END
END


  


  As you can see from the above, when run from the shell prompt it starts ffmpeg and then processes the arguments. But when running as cron, it opens ffmpeg, but ignores, or hangs on the processing of the arguments.

  


  Lastly, I have the following show up in ps ax when I do a check to see what is running :

  


     58 root      0:00 /bin/ash -c /media/pi/_site/pics-alpine.sh 2>&1 | tee /media/pi/_site/alpine.log
   59 root      0:00 {pics-alpine.sh} /bin/ash /media/pi/_site/pics-alpine.sh
   60 root      0:00 tee /media/pi/_site/alpine.log
   61 root      0:00 /usr/bin/ffmpeg -i /media/pi/to-video-back/%04d.jpg /media/pi/_site/back/back-latest.mp4


  


  Those are just sitting there as though they are waiting on input, so I suspect the ffmpeg has a bug, or my cron is not passing the arguments correctly.

  


  Any thoughts on how to fix this ?