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• How to use the ffmpeg overlay_cuda filter to make a SBS video ?

  24 août 2020, par Maxtrix

  FFMPEG a few months ago launched the new version of FFMPEG with the new filter "overlay_cuda", this filter makes the same as the "overlay" but using an Nvidia card for applying it.

  


  I found on the FFMPEG website description of the filter, but no examples of how to use it. The only examples I found are from the developer commits but are to put a video or a photo over another video.

  


  I before the normal overlay filter to do this using a nullsrc image with the twice of width but now I don't know how to with this filter.

  


  Commit description : https://patchwork.ffmpeg.org/project/ffmpeg/patch/20200318071955.2329-1-yyyaroslav@gmail.com/
ffmpeg documentation webpage : https://ffmpeg.org/ffmpeg-filters.html#overlay_005fcuda-1

  


  I hope you can help me.

  


  Update :

  


  I made this FFmpeg order that :

  


  

  1. Input each video.

  


  2. The first video creates padding to the right and then is uploaded to the card's memory.

  


  3. With overlay Cuda, the other video puts on the right of the original video.

  


  


  ffmpeg -y -loglevel info \
-i $video_1  \
-hwaccel cuda -hwaccel_output_format cuda -i $video_2 \
-filter_complex \
" \
[0:v]pad=w=2*iw:h=ih:x=0:y=0,hwupload_cuda[base];
[base][1:v]overlay_cuda=x=800:y=0" \
-an -c:v h264_nvenc overlay_test.mp4


  


  But I get this error message :

  


  [overlay_cuda @ 0x55fdec4b2ec0] Can't overlay nv12 on yuv420p 
[Parsed_overlay_cuda_2 @ 0x55fdec4b2d80] Failed to configure output pad on Parsed_overlay_cuda_2
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #1:0


  


  I have issues with the pixel formats, I hope you can help me.

  


  Update 2 :

  


  I finally solved the pixel format issue and now makes the overlay with the padding (adds space to the overlay video)

  


  This is the command that succeeds :

  


  ffmpeg -y -loglevel info \
-i $video_1  \
-hwaccel cuda -hwaccel_output_format cuda -i $video_2 \
-filter_complex \
" \
[0:v]pad=w=2*iw:h=ih:x=0:y=0,hwupload_cuda,scale_npp=format=nv12[base];
[base][1:v]overlay_cuda=x=800:y=0" \
-an -c:v h264_nvenc overlay_test.mp4



  


  Now I want to change x=800 to a variable like x=iw+1 but it seems this filter doesn't support that. Is there a way to set a global variable ?

  


• Using ffplay as a C++ library ?

  20 janvier 2024, par Victor M

  I want to be able to use the functionality of ffplay as a C++ library, as opposed to a standalone command line tool. Right now in C++, I am able to call ffplay via std::system, but this isn't ideal for performance as is documented extensively here, chief of which is simply that we need to spawn new shell processes in order to execute this.

  


  My application attempts to feed in a bytestream of audio data to a media player. Running a command like cat /tmp/f.mp3 | ffplay -v 0 -nodisp -autoexit - runs smoothly but somewhat slowly/not instantaneously. I would ideally like to be able pass in a bytestream to an ffplay function or via some library that I can link directly to my application. I think ffplay is quite useful here, as it integrates ffmpeg and SDL together.

  


  Is this possible at all ? Or is the only hope to use the command line functionality ?

  


• ffmpeg concatenate with dynamic chunks

  22 décembre 2017, par vongolashu

  The ffmpeg docs for concat lists the following way
  ffmpeg -f concat -i mylist.txt -c copy output

  The mylist.txt file contains file like
  file ’/path/to/file1’
  file ’/path/to/file2’
  file ’/path/to/file3’

  What I am looking is for a way to do this concat in a persistent way where the number of files can keep increasing, for example in livestreaming
  I will be sending chunks of video (mp4 files) of 10 seconds each to my server and want to concat/stitch them together to output to a RTMP stream (for livestreaming)

  If concat is not the proper way to do this, please suggest alternatives.

  Really interested to know how people use the above concept (I hope its how it works) to send video chunks from mobile device for livestreaming