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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 ?

  


• FFmpeg returning error when obs studio tries to enable NVENC

  20 octobre 2022, par Qwerty_PLM

  Apparently the error in obs is "Failed to open NVENC codec : generic error in an external library". I'm using ffmpeg nvenc encoder. the log shows the following lines.

  


  [h264_nvenc @ 0x56341a8cdf40] The selected preset is deprecated. Use p1 to p7 + -tune or fast/medium/slow.
[h264_nvenc @ 0x56341a8cdf40] OpenEncodeSessionEx failed: out of memory (10): (no details)
[h264_nvenc @ 0x56341a8cdf40] No capable devices found


  


  When I run nvidia-smi, the result is below

  


  -----------------------------------------------------------------------------+
| NVIDIA-SMI 520.56.06    Driver Version: 520.56.06    CUDA Version: 11.8     |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|                               |                      |               MIG M. |
|===============================+======================+======================|
|   0  NVIDIA GeForce ...  Off  | 00000000:01:00.0 Off |                  N/A |
| N/A   54C    P5    21W /  N/A |     58MiB /  8192MiB |     26%      Default |
|                               |                      |                  N/A |
+-------------------------------+----------------------+----------------------+
                                                                               
+-----------------------------------------------------------------------------+
| Processes:                                                                  |
|  GPU   GI   CI        PID   Type   Process name                  GPU Memory |
|        ID   ID                                                   Usage      |
|=============================================================================|
|    0   N/A  N/A      5595      G   /usr/lib/Xorg                      12MiB |
|    0   N/A  N/A     15882      G   obs                                44MiB |
+-----------------------------------------------------------------------------+



  


  My environment :

  


  

  • Arch linux with kernel 6.0.2

  


  • RTX 3070 laptop
I hope to find an solution to allow me to use nvenc encoding for recording videos.

  


  


  Software encoding does work, but I'm using a laptop cpu which provides poor performance.

  


  UPD : applying the patch from https://github.com/keylase/nvidia-patch worked but I want to know why it didn't work before because I've never run any process that uses nvenc, and the patch only enables multiple nvenc sessions.

  


• ffmpeg recording audio / video sync issues [closed]

  1er novembre 2022, par sling jones

  I'm using ffmpeg to record NTSC analog video on Linux Fedora 36 using a Blackmagic Intensity Pro 4K for video and a Scarlett 2i2 for audio. I'm using a TBC to avoid dropped frames and to ensure a constant S-Video Y/C framerate on the analog end.

  


  The problem I'm running into is that on playback the audio will start out relatively in sync with the video at the beginning of the captured file but will eventually run ahead of the video eventually becoming many seconds off.

  


  Nothing I do seems to change this or change the degree to which it happens. The audio and video stay in sync throughout the entire video as I'm monitoring the source so I don't understand how they can diverge so much once encoded into a digital file ?

  


  Here is the command I am using :

  


  ffmpeg -hwaccel cuda -fflags +igndts -format_code ntsc -f decklink -raw_format auto -vsync passthrough -rtbufsize 1500M -thread_queue_size 512 -i 'Intensity Pro 4K' -f pulse -rtbufsize 500M -thread_queue_size 512 -i 'Scarlett 2i2 Camera Analog Stereo' -c copy -map 0:1 -map 1:0 "/tmp/ffmpeg-raw/file-raw.avi"


  


  here's the ffprobe output from one of my files :

  


  Input #0, avi, from 'test2-raw.avi':
  Metadata:
    software        : Lavf59.33.100
  Duration: 00:11:42.87, start: 0.000000, bitrate: 169341 kb/s
  Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 720x486, 167801 kb/s, 59.94 fps, 59.94 tbr, 59.94 tbn
  Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 2 channels, s16, 1536 kb/s



  


  As you can see in my code snippet, I've been throwing things at the wall for a bit. I've tried different rtbufsizes, adding -copyts, and going through the different -vsync options. I've tried it with and without hardware acceleration ( I do have a NVIDIA card), +igdts did get rid of a warning but did not help with the sync, as did changing the thread queue sizes.

  


  OBS can do this, why can't I ?