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• Can you think of a reason why windows might not enable audio if noone is logged in ?

  3 juillet 2017, par Caius Jard

  I’m having a bizarre problem with some virtual servers created to record podcasts. They run on amazon AWS as windows server 2012 instances and a small c# app tells FFMPEG to do the heavy lifting of capturing from the virtual screen and reading from the virtual sound card (Virtual Audio Cable : https://en.wikipedia.org/wiki/Virtual_Audio_Cable) via DirectShow filters

  The problem I have is if I leave the machine to do its stuff unattended, the recordings are sometimes silent. If I log in via VNC and watch it doing its stuff the audio is recorded just fine. All other aspects of the test op are the same, and the virtual machine is shut down between successive recordings so each one should theoretically be a clean slate. The app runs under a logged in session (hence the use of VNC rather than RDP)

  I’m now wondering if there is some optimisation of the windows sound engine whereby it doesn’t bother playing audio if it thinks noone is listening. The confusing thing to me is that not every virtual machine suffers these problems ; some of them record fine (and they’re all created from the same seed virtual hard disk image) in unattended mode

  I’m asking this question with the aim of getting together a list of things I can check/look into/debug.. I don’t have much knowledge of how MME/DirectSound/WASAPI work internally...

• Issue with Quick Sync Video (QSV) Hardware Acceleration in FFmpeg

  6 mars 2024, par Linganiveth S.G

  It appears that FFmpeg is unable to create the necessary QSV device for decoding the H.264 video stream.

  


  I am writing to report an issue I encountered while attempting to use No device available for decoder error. hardware acceleration with FFmpeg on my system.

  


  When I run the following command to test QSV hardware acceleration :

  


  ./ffmpeg -hwaccel qsv -i input.mp4 output.ts

  


  I encounter the following error :

  


  [AVHWDeviceContext @ 0x558c6886a5c0] Error setting child device handle: -17
Device creation failed: -1313558101.
No device available for decoder: device type qsv needed for codec h264_qsv.


  


  It appears that FFmpeg is unable to create the necessary QSV device for decoding the H.264 video stream.

  


  Here are some additional details about my system :

  


  **- Operating System : Ubuntu 22.04.4 LTS

  


  

  • FFmpeg Version : 6.0

  


  • Processor : 12th Gen Intel(R) Core(TM) i5-12400

  


  • Graphics Card : Mesa Intel® UHD Graphics 730 (ADL-S GT1)**

  


  


  I have ensured that my system meets the requirements for QSV hardware acceleration, but I am still encountering this issue.

  


  Could anyone please assist me in resolving this issue ? Any guidance or suggestions provided would be greatly appreciated.

  


• Multiple files concatenation using ffmpeg by the use of GPU Hardware acceleration

  30 juin 2021, par bubus

  I need to concatenate multiple mp4, h264 encoded files into single one together with speed up filter, using GPU HW acceleration. I am using Debian 10 Buster 64bit, and the card I am using is Nvidia Gainward GTX960.

  


  I have installed CUDA, together with Nvidia driver and configured ffmpeg with the following parameters :

  


  ./configure --enable-nonfree -–enable-cuda-sdk –enable-libnpp --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64`


  


  The problem is, I believe, that GPU is not working at 100%, so the concatenation takes quite a long time.

  


  The command I am using to concatenate files and speeding them up :

  


  ./ffmpeg -c:v h264_cuvid -f concat -i mylist.txt -c:a copy -c:v h264_nvenc -y -filter:v 'setpts='0.0625'*PTS' -an merged.mp4


  


  Output of nvidia-smi while the above command is being executed :

  


  

  


  ffmpeg version: ffmpeg version N-102801-gb74beba9a9
CUDA version: 11.2
Nvidia driver version: 460.84


  


  I have no idea what else can I do to speed up the concatenation.