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• Problems using Cuda for video transcoding [closed]

  19 août 2022, par Jay Adlard

  I just bought a new pc as my faithful old windows 7 i7 laptop died. Now the laptop had both intel and nvidea gtx660m chips. When I transcoded video with handbrake the intel graphics managed 8fps when I changed over to the nvidia it managed 80fps and the graphics card got nice and hot so was obviously working.

  


  The new machine i bought is a i9 with an nvidea gtx780 running windows 10. When I tried to transcode some video hoping for it to use the cpu and Gpu but no joy,the card stays cool power usage is only a handful of watts higher than it running something simple.I had been using handbrake but I read it doesn’t support Cuda so why the laptop speeded up I don’t know. A friend of mine that is into ffmpeg came round found that ffmpeg reports no Cuda yet the card works fine in every other respect. Unlike the rest of the machine the graphics card wasn’t new but it looked like new…

  


  One thing to note I am not talking about nvenc as the quality is rather poor, no point in capturing uncompressed files cleaning them up and not using an encoder that will do 2 pass and an exhaustive search.
Can anyone recommend a reasonably priced encoder that will use the Cuda cores ?

  


  Has anyone got any idea what the problem is ?

  


• avcodec/dds : fix paletted files

  19 juillet 2015, par Michael Niedermayer

  avcodec/dds : fix paletted files
  Fixes Ticket4664
  The changed fate tests lack red/blue shades and thus look correct
  
  either way
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/dds.c
  • [DH] tests/ref/fate/dds-pal
  • [DH] tests/ref/fate/dds-pal-ati

• Higher quality of JPEG frames extracted with FFMPEG from MP4 video [on hold]

  5 juin 2019, par 2006pmach

  I got a 4k mp4 video file and my goal is to extract the individual frames. Unfortunately, the video is quite big 10GB and storing all the frames lossless (e.g. using png, results in 12MB per frame) is not an option. Therefore, I tired to save directly JPEG images. For me quality is more important than a small file size around 1MB would be good.
  To do so I used FFMPEG as follows :

  ffmpeg -ss 00:04:52 -i video.MP4 -qscale:v $quality -frames:v 1 output-$quality.jpg

  I tried the full range from 2 to 31 for $quality and obtained the blue curve in the plot (PSNR vs. File size)

  Additionally, I extracted the frame and saved it as PNG and used convert from ImageMagick to compress the PNG file as follows :

  convert -quality $quality% frame.png output-$quality.jpg

  Again I tried the full range for $quality from 10 to 100 and obtained the orange line in the plot (The highest quality is 50dB but uses 6MB, so I only show the results up to 2MB).

  Now, my questions are as follows. Why is the quality of ffmpeg that much worse than when using ImageMagick ? Is it possible to increase the quality of the JPEG frames using ffmpeg directly or do I need to go via the PNG and then to JPEG. The later method is somehow suboptimal because it requires storing the png and will be much slower. Any suggestions ? My guess is that ffmpeg trades quality vs. speed...