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• Audio Slowly Desynchronizing When Segmenting

  14 avril 2018, par Nimble

  I use ffmpeg’s ability to segment video while I record so I can record constantly without my hard drive filling up.

  It works really well, expect the audio desynchronizes from the video when the file segments. The video seems to be uninterrupted but I can actually hear a tiny jump in the audio when I join segments later on. One would think that ffmpeg would store packets in a queue during segmentation so nothing is lost but that doesn’t seem to be the case... Any way I could force it to do something like that ?

  Here is my current block :

  ffmpeg -y -thread_queue_size 5096 -f dshow -video_size 3440x1440 -rtbufsize 2147.48M -framerate 100 -pixel_format nv12 ^
  
  -itsoffset 00:00:00.012 -i video="Video (00 Pro Capture HDMI 4K+)" -thread_queue_size 5096 -guess_layout_max 0 -f dshow ^
  
  -rtbufsize 2147.48M -i audio="SPDIF/ADAT (1+2) (RME Fireface UC)" -map 0:0,1:0 -map 1:0 -c:v h264_nvenc -preset: llhp ^
  
  -pix_fmt nv12 -b:v 250M -minrate 250M -maxrate 250M -bufsize 250M -b:a 384k -ac 2 -r 100 -vsync 1 ^
  
  -max_muxing_queue_size 5096 -segment_time 600 -segment_wrap 9 -f segment C:\Users\djcim\Videos\PC\PC\PC%02d.mp4 

  I am delaying the video stream because right out the gate it’s a little bit ahead of the audio.

  PS : aresample or async seem to have no effect or at least not a desirable one.

• FFMPEG : new m3u8 playlist in every hour from the same segmented stream

  23 mars 2018, par iPog

  I’m using the latest Windows build of FFMPEG (by Zeranoe).

  Currently I create 2 outputs from the same raw live video input. I use the tee pseudo-muxer to give the user the following outputs :

  • PRIMARY OUTPUT : transcoded live stream ; using the HLS or the segment muxer ; 14 pieces of 10-second-long segments on a ramdisk.
  • SECONDARY OUTPUT : from the same transcoding I store every segment on the hard drive ; to make the hard drive versions watchable, I create m3u8 playlists with an automated batch script in every hour ; all individual playlist files contain 1 hour of content.

  Is it possible to achieve the same result with FFMPEG only ? I.e. the secondary output should be able to finish the current m3u8 playlist, and start a new one with a new filename at every hour o’clock.

  (My batch-based solution works fine, so it isn’t that important, but it would be nice to know if it is possible at all. I could not find a similar approach in the documentation/wiki.)

• FFMPEG rotates images

  27 mai 2022, par ZomoXYZ

  I am trying to mass-resize images using FFMPEG, and I successfully did it using bash, but I noticed that some of the portrait images got rotated to landscape. Here is the original image, but as you see below, it gets rotated.

  



  

  



  As you see above, the image is rotated. At first, I thought this was due to the -vf scale flag that I was using to resize the images, but I tried the following command and it still rotated the image.

  



  ffmpeg -i input.jpg output.jpg


  



  This doesn't happen with every image, and even not all the portrait images. Also, some images rotate clockwise, while some rotate counter-clockwise. And this isn't a random occurrence, all the images that originally rotated still rotate no matter how many times I run the command.

  



  Console Output

  



  ffmpeg version N-79942-gdc34fa6-tessus Copyright (c) 2000-2016 the FFmpeg developers
  built with Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
  configuration: --cc=/usr/bin/clang --prefix=/opt/ffmpeg --as=yasm --extra-version=tessus --enable-avisynth --enable-fontconfig --enable-gpl --enable-libass --enable-libbluray --enable-libfreetype --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopus --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzmq --enable-version3 --disable-ffplay --disable-indev=qtkit --disable-indev=x11grab_xcb
  libavutil      55. 23.100 / 55. 23.100
  libavcodec     57. 38.100 / 57. 38.100
  libavformat    57. 35.100 / 57. 35.100
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 44.100 /  6. 44.100
  libswscale      4.  1.100 /  4.  1.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
Input #0, image2, from '/Users/jaketr00/Desktop/IMG_1902.JPG':
  Duration: 00:00:00.04, start: 0.000000, bitrate: 1025494 kb/s
    Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 5184x3456, 25 tbr, 25 tbn
[image2 @ 0x7ff751803e00] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
Output #0, image2, to '/Users/jaketr00/Desktop/IMG_19022.JPG':
  Metadata:
    encoder         : Lavf57.35.100
    Stream #0:0: Video: mjpeg, yuvj422p(pc), 5184x3456, q=2-31, 200 kb/s, 25 fps, 25 tbn
    Metadata:
      encoder         : Lavc57.38.100 mjpeg
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> mjpeg (native))
Press [q] to stop, [?] for help
frame=    1 fps=0.0 q=8.2 size=N/A time=00:00:00.04 bitrate=N/A speed=0.0753x   frame=    1 fps=0.0 q=8.2 Lsize=N/A time=00:00:00.04 bitrate=N/A speed=0.0752x    
video:554kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown


  



  Is there any way to stop this from happening ?