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• movtextenc : fix handling of utf-8 subtitles

  28 mars 2018, par Philip Langdale

  movtextenc : fix handling of utf-8 subtitles
  See the earlier fix for movtextdec for details. The equivalent bug is
  
  present on the encoder side as well.
  We need to track the text length in 'characters' (which seems to really
  
  mean codepoints) to ensure that styles are applied across the correct
  
  ranges.
  

  • [DH] libavcodec/movtextenc.c

• FFmpeg - Delay Only Video Stream Of Audio Linked dshow Input

  15 avril 2018, par Nimble

  I’m having a slight issue trying to sync my audio and video up with an acceptable margin of error. Here is my command :

  ffmpeg -y -thread_queue_size 9999 -indexmem 9999 -guess_layout_max 0 -f dshow -video_size 3440x1440 -rtbufsize 2147.48M ^
  
  -framerate 100 -pixel_format nv12 -i video="Video (00 Pro Capture HDMI 4K+)":audio="SPDIF/ADAT (1+2) (RME Fireface UC)" ^
  
  -map 0:0,0:1 -map 0:1 -flags +cgop -force_key_frames expr:gte(t,n_forced*2) -c:v h264_nvenc -preset: llhp -pix_fmt nv12 ^
  
  -b:v 250M -minrate 250M -maxrate 250M -bufsize 250M -c:a aac -ar 44100 -b:a 384k -ac 2 -r 100 -af "aresample=async=250" ^
  
  -vsync 1 -max_muxing_queue_size 9999 -f segment -segment_time 600 -segment_wrap 9 -reset_timestamps 1 ^
  
  C:\Users\djcim\Videos\PC\PC\PC%02d.ts

  My problem is the video comes in slightly ahead of the audio, I can use -itsoffset but then I have to call the video and audio as separate inputs as -itsoffset offsets both audio and video. While this may seem the obvious solution it causes inconsistent audio synchronization if the audio isn’t called with the video. Basically if both audio and video aren’t called at the same time the video can now be ahead or behind with a 2-3 frame margin. When I call them at the same time the video consistently comes in 2 frames ahead of the audio, every time. I just need a way to delay only the video stream without delaying the audio while keeping both audio and video linked from the beginning. I’ve tried this with no luck :

  ffmpeg -y -thread_queue_size 9999 -indexmem 9999 -guess_layout_max 0 -f dshow -video_size 3440x1440 -rtbufsize 2147.48M ^
  
  -framerate 200 -pixel_format nv12 -i video="Video (00 Pro Capture HDMI 4K+)":audio="SPDIF/ADAT (1+2) (RME Fireface UC)" ^
  
  -flags +cgop -force_key_frames expr:gte(t,n_forced*2) -c:v h264_nvenc -preset: llhp -pix_fmt nv12 -b:v 250M ^
  
  -minrate 250M -maxrate 250M -bufsize 250M -c:a aac -ar 44100 -b:a 384k -ac 2 -r 100 ^
  
  -filter_complex "[0:v] setpts=PTS-STARTPTS+.032/TB [v]; [0:a] asetpts=PTS-STARTPTS, aresample=async=250 [a]" -map [v] ^
  
  -map [a] -vsync 1 -max_muxing_queue_size 9999 -f segment -segment_time 600 -segment_wrap 9 -reset_timestamps 1 ^
  
  C:\Users\djcim\Videos\PC\PC\PC%02d.ts

  Just like -itsoffset both video and audio are being delayed. You can delay solely audio with adelay, but there doesn’t seem to be a video delaying equivalent.

  Any help or advice would be greatly appreciated.

• How do I use the CLI interface of FFMpeg from a static build ?

  13 décembre 2019, par deek0146

  I have added this (https://github.com/kewlbear/FFmpeg-iOS-build-script) version of ffmpeg to my project. I can’t see the entry point to the library in the headers included.

  How do I get access to the same text command based system that the stand alone application has, or an equivalent ?

  I would also be happy if someone could point me towards documentation that allows you to use FFmpeg without the command line interface.

  This is what I am trying to execute (I have it working on windows and android using the CLI version of ffmpeg)

  ffmpeg -framerate 30 -i snap%03d.jpg -itsoffset 00:00:03.23333 -itsoffset 00:00:05 -i soundEffect.WAV -c:v libx264 -vf fps=30 -pix_fmt yuv420p result.mp4