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• Color spot in FFmpeg output

  2 juin 2022, par Fabian Garcia

  I work in a company that serves multimedia content to different clients and one of these requests that the videos contain the following specifications :

  


  

  • Codec : H264 High@4.0

  


  • Mode : CBR 1 pass

  


  • Window Buffer : 5 secs

  


  • Frame Rate : 29.97/23.97

  


  • Key Frame Interval : 2 secs

  


  • Bitrate : 4000 Kbps

  


  • Size : 1920x1080

  


  • Window Buffer : 5 secs

  


  • GOP : closed

  


  • GOP size : fixed (no scene change detection)

  


  • Window Buffer : 5 secs

  


  • B Frames : As needed

  


  


  For the above, i build following script :

  


  ffmpeg -hide_banner -nostats -loglevel error -y
-init_hw_device cuda=cuda -hwaccel cuda -hwaccel_device cuda
-i 'video_source.mxf' -filter_hw_device cuda
-filter_complex '[0:v]format=nv12,hwupload,yadif_cuda,scale_cuda=1920:1080[v0]'
-map '[v0]' -c:v h264_nvenc -rc cbr -b:v 4M -bufsize 8M -x264-params "keyint=60:min-keyint=48:no-scenecut" -r '30000/1001' -profile:v high -level:v 4
-map 0:1 -c:a libfdk_aac -b:a 96k -ar 44100 -ac 2 -sample_fmt s16
'output.mp4'


  


  The inconvenience is that the generated output presents some color spots in the scene changes (it's a fade) as can be seen in the attached image.

  


  I could notice that in the output video, the time does not match the input precisely, the output is a few milliseconds ahead, I think that the color spot corresponds to the image that should be shown at that moment in the original video.

  


  Can you see something wrong in script ? Or maybe some concept that i don't know is causing a conflict with the output (This is my first time using ffmpeg).

  


  Thank for your help !

  


  

  


• How to modify the title metadata based on the directory name with FFMPEG ?

  21 décembre 2019, par LincM

  I have video files like : C:\foo\bar.mkv

  But the metadata tags on the videos often reads like nonsense, like blah blah blah foo blah blah bar 981237.mkv

  I’m pretty versed in using FFMPEG to re-encode with different codecs and such, but I would like to be able to edit the metadata to inherit the directory structure, so that the resultant file’s metadata could take C:\foo\bar.mkv and change title metadata to : Foo - Bar.

  Is there any method to do this with FFMPEG ?

  I’m aware that to manually modify metadata in FFMPEG, the command I’d need is -metadata title="foo - bar".

  The question is :

  How do I retrieve the file and directory names for FFMPEG to use them for the title metadata tag ?

• FFmpeg synthesizes multiple videos, the final result is only sound, no picture display

  6 juillet 2023, par Halifax

  1、I first converted mp4 to ts：

  


  -i MyVideo.mp4 -vcodec copy -acodec aac -b:v 10000k MyVideo.ts


  


  2、Then scale the ts and fill the empty space：

  


  -i MyVideo.ts -vf pad=width=iw:height=ih:x=-1:y=0:color='White' -b:v 10000k MyVideo_transform.ts


  


  3、Finally use concat to merge into mp4 files：

  


  -i "concat:MyVideo_transform1.ts|MyVideo_transform2.ts" -acodec copy -vcodec copy -absf aac_adtstoasc -b:v 10000k $outputFilePath"


  


  Finally use concat to merge into mp4 files。

  


  I hope that the final merged result can see the video picture。