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• vima : generate predict_table once, and share it with all decoders

  25 avril 2013, par Paul B Mahol

  vima : generate predict_table once, and share it with all decoders
  Signed-off-by : Paul B Mahol <onemda@gmail.com>
  

  • [DH] libavcodec/vima.c

• configure : don’t generate a git version number if .git isn’t present

  4 septembre 2013, par Sean McGovern

  configure : don’t generate a git version number if .git isn’t present
  

  • [DH] version.sh

• FFMPEG, want to encode 720x480 and automatically scale to 640x480 or 854x480 as necessary depending on the ratio

  2 décembre 2023, par boxylogan

  EDIT : See appended notes at the bottom of the post.

  


  Note : all MKVs are sourced from my original Farscape Starburst DVDs, MPEG2.
I've been slowly re-encoding my old TV shows into a crisper format and I have for some shows, mainly extras (but also full episodes) MKVs that are a mix of 4:3 and 16:9. Usually I open the files up in Mediainfo and find out which ones are 4:3, stick them in one folder to encode in 640x480, then the same with 16:9. It's worked fine for the umpteen amount of times I've had to encode my shows.
I would like to try to expedite the process with a single FFMPEG command that can automatically detect if the files are 4:3 or 16:9 and encode them properly to 640x480 or 854x480.

  


  My main FFMPEG commands have been these two, depending on which aspect ratio I'm using :

  


  854x480p

  


  `for i in *.mkv; do ffmpeg -i "$i" -c:v libx264 -profile:v main -level:v 4.0 -crf 20 -c:a copy -map 0 -vf scale=854:480,setdar=16/9 encoded/"${i%.mkv}.mkv"; done


  


  640x480p

  


  `for i in *.mkv; do ffmpeg -i "$i" -c:v libx264 -profile:v main -level:v 4.0 -crf 20 -c:a copy -map 0 -vf scale=640:480,setdar=4/3 encoded/"${i%.mkv}.mkv"; done


  


  These two have worked fine lately since I got away from the extraneous -x264-params nonsense I picked up years ago. Again, I'm trying to streamline. I found this command a day ago and it SEEMED to look PERFECT :

  


  `for i in *.mkv; do ffmpeg -i "$i" -c:v libx264 -profile:v main -level:v 4.0 -crf 20 -c:a copy -map 0 -vf scale=w='if(gt(dar,854/480),min(854,iw*sar),2*trunc(iw*sar*oh/ih/2))':h='if(gt(dar,854/480),2*trunc(ih*ow/iw/sar/2),min(480,ih))' encoded/"${i%.mkv}.mkv"; done


  


  Looks perfect and works great for 640x480. The only problem is that it returns 852x480, every time. I even tried a modification I found where you set the setsar=1 AFTER the scale filter, and it does nothing.

  


  These are the first warnings I get when I try to run the command, with a 16:9 video, but it still completes :

  


  `[Parsed_scale_0 @ 0x56299c22fcc0] Circular references detected for width 'if(gt(dar, 854/480), min(854,iw*sar), 2*trunc(iw*sar*oh/ih/2))' and height 'if(gt(dar, 854/480), 2*trunc(ih*ow/iw/sar/2), min(480,ih))' - possibly invalid.
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg2video (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[Parsed_scale_0 @ 0x56299c20e5c0] Circular references detected for width 'if(gt(dar, 854/480), min(854,iw*sar), 2*trunc(iw*sar*oh/ih/2))' and height 'if(gt(dar, 854/480), 2*trunc(ih*ow/iw/sar/2), min(480,ih))' - possibly invalid.


  


  It encodes and I can see the resolution it outputs to :

  


  `Stream #0:0(eng): Video: h264 (H264 / 0x34363248), yuv420p(tv, top coded first (swapped)), 852x480 [SAR 1:1 DAR 71:40], q=2-31, 29.97 fps, 1k tbn


  


  The next video is a 4:3 video and gives these warnings, however the video still completes, this time the video encodes properly to 640x480 :your text

  


  `[Parsed_scale_0 @ 0x5623084d4140] Circular references detected for width 'if(gt(dar, 854/480), min(854,iw*sar), 2*trunc(iw*sar*oh/ih/2))' and height 'if(gt(dar, 854/480), 2*trunc(ih*ow/iw/sar/2), min(480,ih))' - possibly invalid.
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg2video (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (copy)`your text`
Press [q] to stop, [?] for help
[Parsed_scale_0 @ 0x5623084d7080] Circular references detected for width 'if(gt(dar, 854/480), min(854,iw*sar), 2*trunc(iw*sar*oh/ih/2))' and height 'if(gt(dar, 854/480), 2*trunc(ih*ow/iw/sar/2), min(480,ih))' - possibly invalid.


  


  The output details :

  


  `Stream #0:0(eng): Video: h264 (H264 / 0x34363248), yuv420p(tv, top coded first (swapped)), 640x48 [SAR 1:1 `your text`DAR 4:3], q=2-31, 29.97 fps, 1k tbn


  


  TL ;DR

  


  EDIT : The actual problem is that the command is encoding the 16:9 aspect ratio files to 852x480 instead of 854x480. 854x480 is actually what I would like. 640x480 for the 4:3 is fine. Apologies, for the lack of clarification.

  


  Videos encode (from original Farscape Starburst DVDs MPEG2) properly to libx264 640x480 for 4:3 but not to 854x480 for 16:9. 16:9 instead encodes to 852x480, despite what command is telling it to do.

  


  Advice ? Thanks in advance ! Anything to make my re-encoding a little bit less tedious. I've been googling for hours and searching, but nothing seems to make it click. Thank you again !