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• diracdec : fix idwt_stride calculation in bytes

  11 janvier 2016, par Andreas Cadhalpun

  diracdec : fix idwt_stride calculation in bytes
  The transformation to bytes must happen after alignment to get the same
  
  resulting pointers as before.
  This fixes segmentation faults in the assembler code.
  The regression was introduced in commit 9553689.
  Reviewed-by : Kieran Kunhya <kierank@obe.tv>
  
  Signed-off-by : Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
  

  • [DH] libavcodec/diracdec.c

• How to "mimic" -c copy when using filters with ffmpeg ? Is there a built-in feature or I'll need some scripting ? [closed]

  29 décembre 2023, par Fabio Freitas

  I'm aware that any stream ffmpeg processes is decoded before applying any desired changes and then re-encoded, which means the stream in question can't simply be copied with -c copy.

  


  Still, I'm not yet very knowledgeable on dealing with media files. Currently, the single issue I'm addressing is cropping black bars from the sides when 4:3 is encoded as 16:9.

  


  That's fairly simple, and I quickly managed to get it going.

  


  Then I noticed some weird stuff via mediainfo and the explorer's side panel. Stream sizes, bitrates and some other details were different than expected.

  


  ---

  


  That's where -c copy comes in. Over the years, every time I tried to solve this, answers would stop at "-c copy can't be used if the stream will be decoded", which is good enough to stop noobs like me from wasting time.

  


  But since I don't know how to use advanced encoding settings, the -c copy I'm looking for is actually how can I re-encode my processed stream using the same (or most similar) settings used before I decoded it.

  


  Is there such an option in ffmpeg ? Are these settings I'm looking for even obtainable by any means ? And if "no" and "yes", could I use ffprobe to write a script for ffmpeg ?

  


  BTW, I'm on Windows 11, but I have Git's SCM tools available.

  


• ffmpeg causing wrong duration on a converted .m2v video ?

  10 octobre 2022, par VILEWORX

  I've been using ffmpeg to convert .mp4 videos to an extremely specific .m2v format for a modding project using the following command :

  


  ffmpeg -i input.mp4 -profile:v high -codec:v mpeg2video -b:v 4000k -vf scale=512:480,colorspace=smpte170m,fps=60 -map 0 -map -0:a -maxrate 4000000 -bufsize 655360 output.m2v

  


  However, the start and end points of the output are not the same as my input file (29 seconds). ffprobe shows "Duration : N/A, bitrate : N/A".

  


  Strangely, the video duration is correct when loaded in Adobe After Effects, is slightly shorter in QuickTime Player, and is only 8 seconds according to Windows File Explorer (on my friend's computer). I suspect the lack of duration and bitrate displayed by ffprobe may have something to do with it, and this doesn't happen with any other format I've tried converting to.

  


  Does anyone know how to fix this ?