Recherche avancée

Sur d’autres sites (8143)

• avformat/mxfenc : add white/black ref /color range

  5 avril 2018, par Michael Niedermayer

  avformat/mxfenc : add white/black ref /color range
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/mxfenc.c
  • [DH] tests/ref/fate/copy-trac4914
  • [DH] tests/ref/fate/mxf-reel_name
  • [DH] tests/ref/fate/time_base
  • [DH] tests/ref/lavf/mxf
  • [DH] tests/ref/lavf/mxf_d10
  • [DH] tests/ref/lavf/mxf_dv25
  • [DH] tests/ref/lavf/mxf_dvcpro50
  • [DH] tests/ref/lavf/mxf_opatom
  • [DH] tests/ref/lavf/mxf_opatom_audio

• FFMPEG - crop and pad a video (keep 3840x1920 but with black borders)

  23 avril 2020, par SteenPetersen

  I am trying to crop a video so that I can remove a chunk of the content from the sides of a 360-degree video file using FFmpeg.

  



  I used the following command and it does part of the job :

  



  ffmpeg -i testVideo.mp4 -vf crop=3072:1920:384:0,pad=3840:1920:384:0 output.mp4


  



  This will remove the sides of the video and that was initially exactly what I wanted (A). Now I'm wondering if it is possible to crop in the same way but to keep the top third of video. As such, A is what I have, B is what I want. :

  



  

  



  I thought I could simply do this :

  



  ffmpeg -i testVideo.mp4 -vf crop=3072:1920:384:640,pad=3840:1920:384:640 output.mp4


  



  But that doesn't seem to work.

  



  Any input would be very helpful.

  


• h264_omx = mostly black videos, libx264 too slow, audio slows everything down

  11 août 2017, par Brendan Grant

  I’m attempting to port a live tv transcoding app from Windows (on .net core) to work on a Raspberry Pi 3.

  Under the hood I uses ffmpeg to take in an mpeg2 stream from a local networked tv tuner and spit out a local HLS stream which is exposed via a custom http server.

  FFmpeg on Linux is configured for build as following :

  sudo ./configure --arch=armhf --target-os=linux --enable-gpl --enable-libx264 --enable-nonfree --enable-mmal --enable-omx --enable-omx-rpi

  Seeing perf issues early on, I tried to boil it down to a simpler form and started using a VOB from a DVD (also mpeg2), take the following example :

  ffmpeg -i VTS_01_2.VOB -c:a aac -c:v h264_omx -b:v 256k -hls_time 3 -hls_wrap 30 "/media/usb1/foo.m3u8"

  Within a matter of seconds, this drops to not only under 30 FPS, but down to the low teens.

  The following runs plenty fast, and is able to keep up when pointed to the tv stream... only all but the first ts file will end up being black (but with audio)... which it turns out the previous line also suffers from :

  ffmpeg -i VTS_01_2.VOB -c:a copy -c:v h264_omx -b:v 256k -hls_time 3 -hls_wrap 30 "/media/usb1/foo.m3u8"

  Aside from the oddity of my choice of audio codecs (ie accepting what is already there vs choosing something else) would so slow down the stream, I also discovered that in order to have visible video... I have to go without hardware assistance.

  ffmpeg -i VTS_01_2.VOB -c:a aac -c:v libx264 -b:v 256k -hls_time 3 -hls_wrap 30 "/media/usb1/foo.m3u8"

  and

  ffmpeg -i VTS_01_2.VOB -c:a copy -c:v libx264 -b:v 256k -hls_time 3 -hls_wrap 30 "/media/usb1/foo.m3u8"

  both turn out video which shows up... and with good audio, except both are too slow in terms of FPS to be able to keep up with a live tv stream.

  Is there something I am missing here to be able to get ffmpeg to be able to handle turning an mpeg2 stream into an h.264 one... and have the resulting files have video ?

  To save space here, I’ve put the console logs on pastebin.

  h264_omx : https://pastebin.com/GK3zN4aB
  libx264 : https://pastebin.com/uEdCwk47

  As I think about it more, the "[mpegts @ 0x2fe0be0] H.264 bitstream error, startcode missing, size 082 drop=0 speed=3.07x" error may be related, but when looking at a longer session we do not see them as regular (as I would think) to obliterate the entire video stream on later files whose sizes are inline with the first : https://pastebin.com/J1EzTqgK