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• Copied .ass Subtitle Has Font Size Changed

  7 novembre 2022, par Rapta

  This is happening when doing an mkv to mkv conversion, with a simple -c:s copy, and whilst the font style, and position are the same, the size ends up being bigger. I'm also playing it with VLC ,if that matters.

  


  Here're the sub settings :
[Script Info]
 ; Script generated by Aegisub r8942
 ; http://www.aegisub.org/
Title : Default Aegisub file
ScriptType : v4.00+
PlayDepth : 0
YCbCr Matrix : TV.601
PlayResX : 708
PlayResY : 480
WrapStyle : 0
ScaledBorderAndShadow : yes

  


  [Aegisub Project Garbage]
Last Style Storage : Default
Video AR Mode : 4
Video AR Value : 1.333333
Video Zoom Percent : 1.000000
Video Position : 35410

  


  [V4+ Styles]
Format : Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style : Default,Funimitation,28,&H00FFFFFF,&H0300FFFF,&H00000000,&H02000000,-1,0,0,0,100,100,1,0,1,2,0,2,40,40,25,1
Style : Lyrics JPN,Faxfont Tone,40,&H00FFFFFF,&H000000FF,&H00000000,&H501D0032,0,0,0,0,100,100,0,0,1,0,0,8,0,0,10,0
Style : Lyrics ENG,Faxfont Tone,36,&H00FFFFFF,&H000000FF,&H00000000,&H501D0032,0,0,0,0,100,100,0,0,1,0,0,2,0,0,6,0
Style : Title,Faxfont Tone,55,&H00FFFFFF,&H000000FF,&H28616161,&H28E0E0E0,-1,0,0,0,100,100,0,0,1,0.5,0.1,2,10,10,20,1
Style : Credits ENG,Faxfont Tone,42,&H00FFFFFF,&H000000FF,&H00000000,&H501D0032,0,0,0,0,100,100,0,0,1,0,0,8,0,0,0,0

  


  And here's a sub example :
[Events]
Format : Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue : 0,0:00:17.95,0:00:20.79,Credits ENG,,0,0,0,,\blur0.6\c&HFFF3ED&\fscx60\fscy76\pos(102.882,73)Planning

  


  If I export the sub from the converted file, all of the settings are the same.

  


  Is there any way to stop the size from changing ?

  


  Thanks

  


  Tried : -c:s copy
Expected : Complete copy.
Resulted : Not a complete copy — the font size was bigger.

  


• AWS Lambda function, API gateway and ffmpeg timeout issue

  3 novembre 2022, par Georgi Stoyanov

  I have created a lambda function, that is extracting the audio stream from a video file using ffmpeg. I have also configured API gateway as a trigger, where I am passing the file to the lambda function in the request body.

  


  The lambda function is working perfectly well with small files, but with bigger files, it needs a bit more time and then I am running into the API gateway timeout, which according to my understanding is set to 29 seconds max.

  


  So when I trigger audio extraction from a bigger file, I am hitting this timeout and my API request fails to return any result even though the transcoding still runs in the background and the file is extracted, so I was wondering what is the best approach to handle those cases, where the execution of the lambda function is taking longer ?

  


  I was thinking to start the transcoding in the background and simply return a JSON with a message that the transcoding might take a couple of minutes, depending on the input file duration, but if I try to push the ffmpeg to the background I am being presented with an error, that the destination file doesn't exist.

  


  os.system(f"{ffmpeg} -loglevel panic -nostdin -i {in_video} -vn -c:a aac -ar 48000 -b:a 192K {out_audio} 2> /dev/null &")


  


  This is the ffmpeg command extracting the audio and transcoding it to AAC.

  


  If I remove the 2> /dev/null & part of the command, it runs just fine, but if I keep it, I get an error :

  


  


  "errorMessage" : "[Errno 2] No such file or directory : 'output_audio.aac'"

  


  


  


  "errorType" : "FileNotFoundError"

  


  


  So I was wondering what is the preferred way to run processes in the background.

  


• Would compressing the extracted source images of a video and reconstructing it make the video smaller ? [closed]

  9 septembre 2022, par tawfikboujeh

  I discovered squoosh and found out that it does crazy compression on images,

  


  Squoosh only works on images and i wanted to scale it to work on videos.

  


  I then wrote this script to convert the video to a set of images that I'll squoosh and then reconstitute to a video again using the almighty ffmpeg.

  


  mkdir out ; rm -rf ./out/*
ffmpeg -i input.mp4 -r 25 buffer.mp4 # for a reason, i needed to create a buffer, this is hacky, but whatever.
ffmpeg -i buffer.mp4 -vf fps=25 out/out%d.png # convert the image into images
squoosh-cli --mozjpeg '{quality: 75}' out/*.png # compress
FRAMERATE=$(ffmpeg -i buffer.mp4 2>&1 | sed -n "s/.*, \(.*\) fp.*/\1/p") # get the framerate from buffer video
ffmpeg -framerate $FRAMERATE -i out/out%d.jpg output.mp4 # reconstitute the video knowing the framerate and having the compressed images


  


  the images are 90% smaller but the video has a bigger size than the original one.

  


  benchmarks :

  


  for the images :

  


  1.jpeg : 98 KB on disk
1.png : 1,7 MB on disk 


  


  for the videos :

  


  input.mp4 : 20 Mb on disk
buffer.mp4 : 21 Mb on disk
output.mp4 : 19 Mb on disk


  


  Any idea compressing the source images would make the video smaller ?