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• avcodec/ac3enc : Don't presume ch_layout to be AV_CHANNEL_ORDER_NATIVE

  7 avril 2024, par Andreas Rheinhardt

  avcodec/ac3enc : Don't presume ch_layout to be AV_CHANNEL_ORDER_NATIVE
  It is perfectly legal for users to use a custom layout
  
  that is equivalent to a supported native one.
  
  In this case the union in AVChannelLayout is not an uint64_t mask,
  
  but a pointer to a custom map.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/ac3enc.c

• ffmpeg with partial motion detection

  2 mars 2021, par Silentfury

  I have video files from a static surveillance camera and I try to re-encode them using some sort of motion detection filter (keeping the movements, droping the stills) in order to save space and play time.

  


  I have successfully tried the two below filter options but it still feels not good enough. :

  


  

  • mpdecimate e.g. -vf "mpdecimate=hi=6480:lo=6420:frac=0.1,setpts=N/(15*TB)"

  


  • select (e.g. -vf "select=gt(scene,0.4)")

  


  


  The main problem is a moving bush in the camera view, that I would like to exclude from the motion detection.

  


  Is there other/better ways of applying motion detection (and stills dropping) to ffmpeg ?
Is there any way to mask areas of the video that will be ignored in the above mentioned (or any other) motion detection filter/method ?

  


  Many thanks in advance !

  


  Edit :
in the mean time I found this excellent answer from Gyan

  


  I am testing this now but would still appreciate other ideas

  


• what codec to specify to accessing my HDMI-to-USB adaptor, under Linux ? [closed]

  14 mai 2022, par David

  A week or so ago,I bought a HDMI-to-USB adapter, to use to capture video
TV content from my TV's set-top box. (Xfinity, if it matters. Box generically is :
"XiD X1"...I have both the Pace and the Cisco models available here in this house.)

  


  Specifically, here's the adapter I bought,from Amazon :
https://www.amazon.com/gp/product/B09FLN63B3

  


  So, I'm fluent in both Windows (Win-11) and Linux (Debian 'Bullseye', on my chromebook).

  


  The adapter does not come with any recommendations for what software/drivers to (try to) use, but I was prepared for that.
After some google searches, I decided to first try using the cmd-line
'ffmpeg' program, because I'm
quite familiar with that (excellent !) piece of open-source software !

  


  So, after a day or two of (mostly) success recordings under Win-11, using
ffmpeg's Microsoft-based 'dshow' (aka 'DirectShow'), I decided to attempt to get
up to the same level of accomplishment on my Chromebook, under Linux, also
using 'ffmpeg'.

  


  [Ok...a very brief explanation of 'mostly' successful. I'll
post another separate question here, about the specifics of my glitches,
using 'dshow' on Windows. But, essentially, when I try to record to a MP4
file, I get 2 scenarios of glitch : #1 : Suddenly, dropped packets surges up,
and I get "1000 dropped' yellow msg #2 : On other trials, I get '...contains
no image...'.) So, I figured I should first give a Linux a chance,
before spending more effort trying to resolve the glitches on Windows.]

  


  My first snag, was learning that 'dshow' seems to be specific to 'Windows',
and thus ffmpeg is getting 'unknown' for my reference to 'dshow'. After more hours of 'guessing', I've finally learned/concluded that there are other things
(something call "DeckLink" is one such alternative ?) for Linux, but I'm unclear
what extra Linux packages might exist for ffmpeg support, or whether I will need to built a more complete 'ffmpeg' (e.g. from source code), to get things going under Linux ?

  


  Is my device able to be accessed from some tools other than 'ffmpeg' ?
(e.g. VLC or Handbrake or whatever ?) more easily, on the Linux platform ?

  


  [If I had to, I'd probably invest another $20-$50 in some other hardware
device that goes from HDMI-to-USB (USB-A/B), if it were ]

  


  All ideas are welcome...(TIA)

  


  — Dave