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• ffmpeg status & quality / cuda (CPU/GPU)

  18 juin 2024, par cocco

  ffmpeg am I doing it right ?

  


  So much time has passed since I use ffmpeg to convert clips on my home web server, now that mp4 (h264 & aac) is the current overall standard (works on every console, smartphone, smartTV, pc) I decided to convert my old clips from various digital cameras to to this new container/codecs.

  


  

  1. less space & the same quality.

  


  2. compatibility

  


  3. support for tags (subler for mac)

  


  


  after some research I opted for ffmpeg because of various reasons

  


  

  1. commandline (I made my simple web interface with default settings which I execute with php's exec)

  


  2. the quality/size amount

  


  


  I read that many expensive video conversion software programs are not able to handle low bitrate videos properly. I also tested some of them and personally I could not find the proper export settings or I was not impressed by the results... some had fixed default export settings, most had a lower video quality at the same filesize. ffmpeg allows me to set the -crf (18-24 usually) and -preset (veryslow, fast..) which allows me to reduce the filesize drastically maintaining the same visible quality.

  


  Said that I'm using the preset at very slow (there is also placebo but the final video file is only 1% smaller in size).

  


  And here is the command I use

  


  ffmpeg
-y //overwrite the file if it exists

-i INPUTFILE // replace with the input file

-metadata title=THETITLE // set a nice title, visible on modern devices
-metadata date=THEDATE // set a nice title, visible on modern devices

-c:v libx264 // use the h264 codec
 -crf 21 // try different numbers between 18-26
 -preset veryslow // placebo,slow,fast,ultrafast==big file 
 -tune film // tune it a little
 -pix_fmt yuv420p // preferred on most modern devices
 -profile:v main // preferred on most modern devices
 -level 3.1 // preferred on most modern devices 
 -refs 4 // preferred on most modern devices

-c:a libfdk_aac // use aac
 -metadata:s:a language=eng // set a language, visible on modern devices 
 -b:a 128k // audio bitrate 128k is like mp3 192k
 -ar 48000 // 44100 ... whatever
 -ac 2 // audiochannels
 -movflags +faststart //move the metadata in the front of the video so it loads faster

OUTPUTFILE


  


  Some camcorder clips with m2ts already have the avc/h264 compatible codec so I just copy the stream.
  
some have the ac3/Dolby surround audio. I convert the audio but keep the ac3 as second audio track mapping the ffmpeg streams. this allows me to watch the mp4 on browsers and mobile devices but I'm able to keep the surround sound to playback on some tv's, advanced media players or devices like apple tv.

  


  Not that I'm not happy with the speed (using quad core's) but I recently read again about cuda opencl and there is also the simple fact that I'm not using other converters than ffmpeg since a lot of time.

  


  Is ffmpeg (with the setting I use) a good converter to keep the same video quality than the source reducing the space occupied by and average of 30-40% ?

  


  Is GPU conversion really that bad (cuda .. testing a gtx970) ?
it would be nice to add some more speed to the conversions by using both the gpu and the cpu..but for my understanding they cannot work together ??? and using only GPU is a drastically quality loss...cpu is more precise, GPU is faster in calculation are too imprecise from what I read.. so expensive software programs use cuda only for preview purpose... right ?

  


  Is ffmpeg or another software compatible with CPU+GPU encoding ?
I really don't remember where, but I read that the ffmpeg is not a good videoconverter.

  


  I'm really happy with the size/quality, I gained an average of 30% in space with no visible quality loss. With some extra parameters i can adjust some really old analog videos that are deinterlaced in a really bad way.

  


  


  maybe I could gain more size/quality with another software ???

  


  


  note : I like ffmpeg.it's free and it has commandline so I can create my own interface with php html & js and use it on various machines without the need to install it in every device I use. I upload the idevice clips directly to the ffmpeg server.

  


  EDIT :

  


  @talonmies ...cuda tag removed :

  


  http://www.nvidia.com/object/cuda_home_new.html

  


  


  CUDA® is a parallel computing platform and programming model invented
by NVIDIA. It enables dramatic increases in computing performance by
harnessing the power of the graphics processing unit (GPU). With
millions of CUDA-enabled GPUs sold to date, software developers,
scientists and researchers are finding broad-ranging uses for GPU
computing with CUDA. Here are a few examples : - See more at :
http://www.nvidia.com/object/cuda_home_new.html#sthash.dEYaqae7.dpuf

  


  


  isn't cuda the programming model that a theoretical ffmpeg library should support to handle GPU encoding on nvidia cards like the gtx 970 ?? like the badaboom software http://www.geforce.com/games-applications/pc-applications/badaboom-media-converter.

  


• avcodec/h264dec : fix possible out-of-bounds array access

  25 août 2021, par Niklas Haas

  avcodec/h264dec : fix possible out-of-bounds array access
  If slice_type is > 9, the access to ff_h264_golomb_to_pict_type is
  
  out-of-bounds. Fix this by simply setting the slice_type to 0 in this
  
  case.
  This is completely inconsequential because the value is only being used
  
  to being used as an offset in the calculation of the film grain seed
  
  value, a corruption of which is practically invisible.
  Fixes coverity ticket #1490802
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/h264dec.c

• Why does x264 keep giving me "command not found" error on my Mac ? [closed]

  2 juillet 2021, par hd-dvd

  I just installed x264 via Homebrew on my Mac running MacOS 11.4 Big Sur. I'm trying to encode a video but I can't get x264 to run properly.

  


  This is the command I am running in the Terminal :

  


  x264 --bitrate 25000 --preset veryslow --bluray-compat --tune film --vbv-maxrate 40000 --vbv-bufsize 30000 --level 4.1 --keyint 30 --open-gop --slices 4 --fake-interlaced --colorprim "bt709" --transfer "bt709" --colormatrix "bt709" --sar 1:1 --pass 1 -o out.264 in.mp4

  


  and this is what it outputs :

  


  bash: x264 --bitrate 25000 --preset veryslow: command not found

  


  If I delete the --preset part then it just gets hung up on some other part, like --tune.

  


  I have tried brew doctor and there are no errors.

  


  If I just run x264 then it gives me x264 [error]: No input file. Run x264 --help for a list of options. so it seems as if x264 is installed. I don't know where to begin troubleshooting this but I'd like to get it to work.

  


  If I simplify the command way down to x264 -o out.264 in.mp4 then I get :

  


  avs [error]: failed to load avisynth
raw [error]: raw input requires a resolution.
x264 [error]: could not open input file `in.mp4' via any method!


  


  I would greatly appreciate some pointers on how to get this working.