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• avcodec/nvenc : Declare support for P016

  25 février 2018, par Philip Langdale

  avcodec/nvenc : Declare support for P016
  nvenc doesn't support P016, but we have two problems today :
  1) We declare support for YUV444P16 which nvenc also doesn't support.
  
     We do this because it's the only pix_fmt we have that can
  
     approximate nvenc's internal format that is YUV444P10 with data in
  
     MSBs instead of LSBs. Because the declared format is a 16bit one,
  
     it will be preferrentially chosen when encoding >10bit content,
  
     but that content will normally be YUV420P12 or P016 which should
  
     get mapped to P010 and not YUV444P10.
  2) Transcoding P016 content with nvenc should be possible in a pure
  
     hardware pipeline, and that can't be done if nvenc doesn't say it
  
     accepts P016. By mapping it to P010, we can use it, albeit with
  
     truncation. I have established that swscale doesn't know how to
  
     dither to 10bits so we'd get truncation anyway, even if we tried
  
     to do this 'properly'.
  

  • [DH] libavcodec/nvenc.c
  • [DH] libavcodec/version.h

• How to get iOS App Preview video bitrate in range

  29 avril 2019, par JKaz

  Creating new App Previews for App Store Connect has always been difficult. Time to do it again (new app version) and running into same issue without resolution this time.

  Making the video is easy enough, recording it with Quicktime and either a connected device or through Simulator (and the xcrun simctl io booted recordVideo <filename>.<file extension="extension"></file></filename> Terminal command).

  I can open that in iMovie, create a new App Preview, and export/share the preview with proper size, length, frame rate per Apple specs. But the bit rate is always too low ( 4 mbps) and it’s required to be 10-12 mbps (and I’ve had video reject be/c of that). In the past I could always make some change to the .mp4, in conjunction with something like ffmpeg -i ~/appVideo.mp4 -b:v 11M ~/appPreview.mp4 to get the file into the target range, but that’s not helping today, and neither is Developer Tech Support.

  Apple’s documentation says :

  To export the final video, click Share in the toolbar, then choose App
  Preview. The export settings are automatically configured to meet App
  Store requirements. iMovie exports the final video at the correct
  resolution based on the device from which your clips were captured.

  I’ve done that and more, and bit rate is still out of range (every other attribute is in spec). I’ve tried the recommendations from a bunch of other threads here for http://video.online-convert.com/convert-to-mp4 and others, and none seem to do the trick. Am I missing something obvious re bitrate ? Is it this hard for everyone ?

  Thank you.

• how to ignore or fix false 'unmet dependencies' error ?

  31 août 2014, par yy502

  OS: LMDE 201403

  I previously installed OpenShot (a video editing software), which depends on libmlt6, and libmlt6 depends on ffmpeg. The chain of dependencies auto-installed just fine.

  Today I compiled and installed the latest ffmpeg v2.3.3 and apt-get starts to complain :

  You might want to run 'apt-get -f install' to correct these:
  
  The following packages have unmet dependencies:
  
   libmlt6 : Depends: ffmpeg (>= 5:0.6.2~) but 2.3.3-1 is to be installed
  
  E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

  Well, I’m sure my compiled version of ffmpeg is newer than whatever version libmlt6 requires, but the package manager does not seem to understand the new version number. How can I ignore or fix false ’unmet dependencies’ error, please ?

  Thanks for your time !

  Edit :

  Executing apt-get -f install would install the ffmpeg from repository to /usr/bin/ and uninstall/overwrite my compiled version of ffmpeg in /usr/local/bin/... not really the solution I’m after...

  Edit2 :

  the auto fix of apt-get will remove my compiled version of ffmpeg as prompted below :

  sudo apt-get install -f
  
  Reading package lists... Done
  
  Building dependency tree       
  
  Reading state information... Done
  
  Correcting dependencies... Done
  
  The following extra packages will be installed:
  
    ffmpeg
  
  Suggested packages:
  
    nvidia-libvdpau1
  
  The following packages will be upgraded:
  
    ffmpeg
  
  1 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
  
  Need to get 0 B/1,307 kB of archives.
  
  After this operation, 242 MB disk space will be freed.
  
  Do you want to continue? [Y/n] n
  
  Abort.