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• Encoding video stream by http protocol using ffmpeg library

  20 juillet 2014, par user3780677

  I’m trying to encode video files, that users upload on my server.
  I interpretate file as stream, incoming on my server by http protocol and use ffmpeg for realtime file encoding, while upload procedure executes.

  When source file have .avi format, I have successful encoding result, but on .mp4 format appears error :

  ---------------------
  
  [buffer @ 0000000000308380] Unable to parse option value "-1" as pixel format
  
  Last message repeated 1 times
  
  [buffer @ 0000000000308380] Error setting option pix_fmt to value -1.
  
  ---------------------

  I think this might be because .mp4 contains "moov atom" data in the end of file.
  I think so because when I processing file by "-movflags faststart" command before encoding, I also have successful result.

  That is the command i using now :

  ffmpeg -i http://myhost.com/app/video/video2.mp4 -f mp4 -vcodec libx264 -b:v 800K -acodec libvo_aacenc -b:a 128K -ar 44100 -ac 2 -y c:/watch-and-get/video/video5.mp4

  Can I resolve this problem and encode multiple video formats as a stream without any excess steps ?

• do something with script output

  3 novembre 2017, par Opolo Webdesign

  I’m lazy :) so I would like to automate some things on my network. Currently I’m running a script that automatically downloads the series I watch every week. Based on what is downloaded another script searches the web for subtitles. Some downloads however have subtitles with them, so searching for subtitles is not necessary. I would like to check every download for subtitles and get notified (or better move the file) if the file has the correct subtitles.

  I started with the following :

  find /volume2/Downloads/ -type f -mmin -30 | while IFS= read -r file; do
  
      ffmpeg -i "${file}"
  
  done

  This works and shows me the output of the ffmpeg command for each file newer than 30 minutes. I would like to work with the result given by ffmpeg so that when certain characters are present in the output, I’m notified via mail. My Linux scripting skills however stop at the script I got. I’m a web developer so I understand the logic behind a script like this, but not the specific code or commands.

  Characters that I’m looking for :

  • (eng) : Subtitle :
  • (dut) : Subtitle :

  Can this be done ?

  Edit :

  I did some more research and did some changes to my script :

  find /volume2/Downloads/ -type f -mmin -60 | while IFS= read -r file; do
  
      if ffmpeg -i "${file}" | grep -q '(dut): Subtitle:'; then
  
          echo "matched"
  
      fi
  
  done

  Instead of "matched" it shows the ffmpeg output, but it’s probably a step in the right direction ?

• How to improve Desktop capture performance and quality with ffmpeg [closed]

  6 novembre 2024, par Francesco Bramato

  I'm developing a game capture feature from my Electron app. I'm working on this since a while and tried a lot of different parameters combinations, now i'm running out of ideas :)

  


  I've read tons of ffmpeg documentation, SO posts, other sites, but i'm not really a ffmpeg expert or video editing pro.

  


  This is how it works now :

  


  The app spawn an ffmpeg command based on user's settings :

  


  

  • Output format (mp4, mkv, avi)

  


  • Framerate (12, 24, 30, 60)

  


  • Codec (X264, NVidia NVENC, AMD AMF)

  


  • Bitrate (from 1000 to 10000kpbs)

  


  • Presets (for X264)

  


  • Audio output (a dshow device like StereoMix or VB-Cable) and Audio input (a dshow device like the Microphone)

  


  • Final Resolution (720p, 1080p, 2K, Original Size)

  


  


  The command executed, as far, is :

  


  ffmpeg.exe -nostats -hide_banner -hwaccel cuda -hwaccel_output_format cuda -f gdigrab -draw_mouse 0 -framerate 60 -offset_x 0 -offset_y 0 -video_size 2560x1440 -i desktop -f dshow -i audio=@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\wave_{D61FA53D-FA37-4BE7-BE2F-4005F94790BB} -ar 44100 -colorspace bt709 -color_trc bt709 -color_primaries bt709 -c:v h264_nvenc -b:v 6000k -preset slow -rc cbr -profile:v high -g 60 -acodec aac -maxrate 6000k -bufsize 12000k -pix_fmt yuv420p -f mpegts -


  


  one of the settings is the recording mode : full game session or replay buffer.
In case of full game session, the output is a file, for replay buffer is stdout.

  


  The output format is mpegts because, as far i have read in a lot of places, the video stream can be cut in any moment.

  


  Replays are cutted with different past and future duration based on game events.

  


  In full game session, the replays are cutted directly from the mpegts.

  


  In replay buffer mode, the ffmpeg stdout is redirect to the app that record the buffer (1 or 2 minutes), when the replay must be created, the app saves on the disk the buffer section according to past and future duration and with another ffmpeg command, copy it to a mp4 or mkv final file.

  


  Generally speaking, this works reliably.

  


  There are few issues :

  


  

  • nonetheless i ask ffmpeg to capture at 60fps, the final result is at 30fps (using -r 60 will speed up the final result)

  


  • some user has reported FPS drops in-game, specially when using NVidia NVENC (and having a NVIDIA GPU), using X264 seems save some FPS

  


  • colors are strange compared to original, what i see on screen, they seem washed out - i could have solved this using -colorspace bt709 -color_trc bt709 -color_primaries bt709 but don't know if is the right choice

  


  • NVIDIA NVenc with any other preset that is not slow creates videos terribly laggy

  


  


  here two examples, 60 FPS, NVIDIA NVENC (slow, 6000kbs, MP4

  


  Recorded by my app : https://www.youtube.com/watch?v=Msm62IwHdlk

  


  Recorded by OB with nearly same settings : https://youtu.be/WuHoLh26W7E

  


  Hope someone can help me

  


  Thanks !