Recherche avancée

Sur d’autres sites (2703)

• h265_videotoolbox for Apple Chips Not working with ffmpeg

  22 janvier 2024, par Martin Julien

  I have a 16-inch Macbook Pro.
System :
Model Name : MacBook Pro
Chip : Apple M1 Max
Total Number of Cores : 10 (8 performance and 2 efficiency)
Memory : 64 GB

  


  You can take advantage of apple chips to encode faster by replacing the usual line :
-c:v libx265 by -c:v h265_videotoolbox.

  


  Here's an example.
Since h265 doesn't work at the moment, here's a line that works just fine :

  


  for i in *.mp4; do ffmpeg -i "$i" -c:v h264_videotoolbox -b:v 2000k -c:a aac -b:a 192k -s 1920x1080 -threads 8 "${i%.*}_1.mp4"; done

  


  The version of ffmpeg installed on my mac is the latest : 6.1.1

  


  My problem :
I want to encode in h265. My command line is :
for i in *.mp4; do ffmpeg -i "$i" -c:v h265_videotoolbox -b:v 2000k -c:a aac -b:a 192k -s 1920x1080 -threads 8 "${i%.*}_1.mp4"; done

  


  Everything should work in theory. But I get this from the Shell :

  


  [vost#0:0 @ 0x150f06fd0] Unknown encoder 'h265_videotoolbox' [vost#0:0 @ 0x150f06fd0] Error selecting an encoder Error opening output file Denis_1.mp4. Error opening output files: Encoder not found

  


  My attempts :

  


  I spent a lot of time with ChatGPT to solve the problem, but nothing worked. So I'm asking the question here to see if anyone has had the same problem as me and if there's a solution to fix it.

  


  Thank you for your help,

  


  best regards,
Martin

  


• avcodec : improve precission for cbrtf() emulation

  15 octobre 2013, par Michael Niedermayer

  avcodec : improve precission for cbrtf() emulation
  cbrtf() took floats but it represented 1/3 exactly
  
  and even if not more precission should be better in theory
  
  for the table generation
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/cbrt_tablegen.h
  • [DH] libavcodec/mpegaudio_tablegen.h

• Why does ffmpeg have bigger latency on dark images ?

  19 novembre 2017, par doodoroma

  I have a c# application to stream real camera images using ffmpeg. The input images are in raw, 8-bit gray-scale format. I created an ffmpeg stream using the standard input to feed the images and send the output packages to websocket clients.

  I start an external ffmpeg process using this config :

  -f rawvideo -pixel_format gray -video_size " + camera.Width.ToString() + "x" + camera.Height.ToString() + " -framerate 25 -i - -f mpeg1video -b:v 512k -s 320x240 -

  Typical image size is 1040*1392 pixels

  I display the stream on the browser, using jsmpeg library

  This works with a reasonable latency ( 500ms on localhost), but when the camera image is really dark (black image), the latency is extremely big ( 2-3 seconds on localhost). When there is something bright on the image again after a black period, it takes 2-3 seconds to "synchronize".

  I was thinking that black images are really easy to compress and will generate really small packages, jsmpeg has almost no information to display and wait until a complete data package arrives, but I couldn’t prove my theory.

  I played with ffmpeg parameters like bitrate and fps but nothing has changed.

  Is there any settings which I could try ?