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• mpegts muxer, DVB subtitles encoder : common DVB subtitles payload

  11 janvier 2014, par Serhii Marchuk

  mpegts muxer, DVB subtitles encoder : common DVB subtitles payload
  Improved DVB subtitles encoder to generate AVPacket.data in the same
  
  format as generates MPEGTS demuxer + DVB subtitles parser. So now single
  
  format of DVB subtitles data is used across all the components of FFmpeg :
  
  only subtitles payload WITHOUT 0x20 0x00 bytes at the beginning and 0xFF
  
  trailing byte.
  Improved MPEGTS muxer to support format of DVB subtitles in
  
  AVPacket.data described above : while muxing we add two bytes 0x20 0x00 to
  
  the beginning of and 0xFF to the end of DVB subtitles payload.
  The patch fixes DVB subtitle copy problems : tickets #2989 fully and #2024
  
  partly.
  Signed-off-by : Clément Bœsch <u@pkh.me>
  

  • [DH] libavcodec/dvbsub.c
  • [DH] libavcodec/version.h
  • [DH] libavformat/mpegtsenc.c
  • [DH] libavformat/version.h

• 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 !

  


• avcodec/sanm : disable left/top for fullscreen codecs

  11 mars, par Manuel Lauss

  avcodec/sanm : disable left/top for fullscreen codecs
  The block-based codecs 37/47/48 work on the full frame, and there's no
  
  existing LucasArts game video that uses left/top offsets for these,
  
  as it doesn't make sense. Ignore the left/top parameters for these codecs.
  Signed-off-by : Manuel Lauss <manuel.lauss@gmail.com>
  

  • [DH] libavcodec/sanm.c