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• Bypass Nvidia's 2 Stream Encode Limit On Windows

  28 novembre 2018, par Nimble

  I’m trying to encode 3 video streams simultaneously in FFmpeg but due to Nvidia’s 2 stream encode limit on GTX / RTX GPUs I have to encode one of the streams with my CPU. This forces me to output multiple files as opposed to one properly mapped file containing all audio and video streams which has many drawbacks involving synchronization and ease of use.

  Before actually considering investing $1000+ in a comparable Quadro GPU, which has no encode stream limits, I thought I’d search around to see if anyone has bypassed said limit. Eventually I came across this GitHub repository :
  https://github.com/keylase/nvidia-patch

  It seems to actually work... but it’s Linux only. Much of my hardware is incompatible with Linux so migration just isn’t an option for me. Not being smart enough to learn from this method and apply it to a Windows environment I kept looking and came across this repository :
  https://github.com/Matviy/nvidia-NVENC-multi-session-patch

  It would seem this is a method to bypass the limit on Windows but the instructions are way over my head. I’ve asked a few of my buddies who are experienced in coding but each one only seems to understand each method to a point and can’t really help.

  Was hoping someone could give some insight on the subject, possibly offering a solution, or confirming that the instructions are simply too vague.

• avcodec/vdpau : Support for VDPAU accelerated HEVC decoding

  13 juin 2015, par Philip Langdale

  avcodec/vdpau : Support for VDPAU accelerated HEVC decoding
  This change introduces basic support for HEVC decoding through vdpau.
  
  Right now, there are problems with the nvidia driver/library implementation
  
  that mean that frames are incorrectly laid out in memory when they are
  
  returned from the decoder, and it is normally impossible to recover the
  
  complete decoded frame due to loss of data from alignment inconsistencies.
  I obviously hope that nvidia will be fixing it in due course - I’ve verified
  
  the problems exist with their example application.
  As such, this support is not useful for any real world application, but I
  
  believe that it is correct (with the caveat that the mangled frames may hide
  
  problems) and will work properly once the nvidia problem is fixed.
  Right now it appears that any file encoded by x265 or nvenc is decoded
  
  correctly, but that’s because these files don’t use a bunch of HEVC
  
  features.
  Quick summary :
  Features that seem to work :
  1) Short Term References
  
  2) Scaling Lists
  
  3) Tiling
  Features with known problems :
  1) Long Term References
  It’s hard to tell what’s going on here. After I read the nvidia example
  
  app that does not set the IsLongTerm flag on LTRs, and changed my code,
  
  a bunch of frames using LTR started to display correctly, but there
  
  are still samples with glitches that are related to LTRs.
  In terms of real world files, both x265 and nvenc only use short term
  
  refs from this list. The divx encoder seems similar.
  Signed-off-by : Philip Langdale <philipl@overt.org>
  

  • [DH] configure
  • [DH] libavcodec/Makefile
  • [DH] libavcodec/allcodecs.c
  • [DH] libavcodec/hevc.c
  • [DH] libavcodec/vdpau_hevc.c
  • [DH] libavcodec/vdpau_internal.h

• Fade out in ffmpeg when creating a video from a still image is wonky ?

  13 juin 2017, par Matt W

  I’m creating a video that :

  • uses a still image as a source
  • has a text overlay
  • fades in and out
  • has a silent stereo audio track.

  So far, I have this, and it (almost) works correctly :

  ffmpeg -f lavfi -i "aevalsrc=0|0" -loop 1 -i turtle-2.jpg  -c:v libx264 -t 5 -r 30 -s 1920x1080 -aspect 16:9 -pix_fmt yuv420p -filter:v drawtext="fontsize=130:fontfile=comic.ttf:text='hello world':x=(w-text_w)*.25:y=(h-text_h)*.75",fade=in:0:60,fade=out:90:60 -acodec aac turtle11.mp4

  The only problem is that the fade out doesn’t seem to be going to black, even tho this is a 150 frame video and I believe I am following the ffmpeg documentation correctly.

  The resulting video is here :

  http://video.blivenyc.com/vid-from-image/turtle11.mp4

  Any thoughts ?