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• Loop a song for a certain amount of time using FFMPEG

  10 avril 2017, par Eduardo Perez

  So, I am trying to loop a song from a video game for one hour, using FFMPEG on Linux or in Windows 10 Bash. I have 3 versions of the song, they are as follows :

  1.Full song in OGG format with LOOPSTART and LOOPLENGTH metadata.
  
  2.Same song in OGG format, except only the segment before LOOPSTART.
  
  3.Same song in OGG format, except only the segment from LOOPSTART to LOOPSTART+LOOPLENGTH.

  So, what I want to do is use either the full song file for the loop, which I don’t think FFMPEG supports, or use the files for the beginning and looping portions of the song. Basically, I want to have FFMPEG create a song which starts off with the beginning segment of the song and loops the looping segment indefinitely until an hour has been played. If possible, I also want a second command so I can add an image or an MP4 video to be shown in a loop while the song is being played, but in the case of a video being used to be shown while the song is played, the music from that video won’t be merged with the music from the song. What command should I use for this ?

• 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 !

  


• 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 !