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• 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 !

  


• lavc/libopenh264 : Drop openh264 runtime version checks

  9 décembre 2023, par Kalev Lember

  lavc/libopenh264 : Drop openh264 runtime version checks
  With the way the runtime checks are currently set up, every single
  
  openh264 release, no matter how minor, is considered an ABI break and
  
  requires ffmpeg recompilation. This is unnecessarily strict because it
  
  doesn't allow downstream distributions to ship any openh264 bug fix
  
  version updates without breaking ffmpeg's openh264 support.
  Years ago, at the time when ffmpeg's openh264 support was merged,
  
  openh264 releases were done without a versioned soname (the library was
  
  just libopenh264.so, unversioned). Since then, starting with version
  
  1.3.0, openh264 has started using versioned sonames and the intent has
  
  been to bump the soname every time there's a new release with an ABI
  
  change.
  This patch drops the exact version check and instead adds a minimum
  
  requirement on 1.3.0 to the configure script.
  Signed-off-by : Kalev Lember <klember@redhat.com>
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] configure
  • [DH] libavcodec/libopenh264.c
  • [DH] libavcodec/libopenh264.h
  • [DH] libavcodec/libopenh264dec.c
  • [DH] libavcodec/libopenh264enc.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.