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• avformat : add skip_estimate_duration_from_pts

  16 mai 2018, par Aman Gupta

  avformat : add skip_estimate_duration_from_pts
  For seekable mpegts streams, duration is calculated from
  
  pts by seeking to the end of the file for a pts and subtracting
  
  the initial pts to compute a duration.
  This can be expensive in terms of added latency during
  
  probe, especially when streaming over a network. This new
  
  option lets you skip the duration calculation, which is useful
  
  when you don't care about the value and want to save some overhead.
  This patch is particularly useful when dealing with live mpegts
  
  streams. Normally such streams are not seekable, so durations
  
  are not calculated. However in my case I am dealing with a seekable
  
  live mpegts stream (networked access to a .ts file which is still
  
  being appended to).
  Signed-off-by : Aman Gupta <aman@tmm1.net>
  

  • [DH] libavformat/avformat.h
  • [DH] libavformat/options_table.h
  • [DH] libavformat/utils.c

• ffmpeg library - why is the Bitrate parameter change on encoding

  22 avril 2021, par QRrabbit

  Hello forum and all the members of the community !

  


  I have this question on ffmpeg library, why does the bitrate parameter not retained after encoding, even though I explicitly specify the desired rate.

  


  Input file ffprobe :

  


    Duration: 00:00:10.01, start: 0.000000, bitrate: 534719 kb/s
    Stream #0:0(eng): Video: qtrle (rle  / 0x20656C72), argb(progressive), 1920x1080, 533881 kb/s, SAR 1:1 DAR 16:9, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc (default)
    Metadata:
      creation_time   : 2021-04-13T16:35:16.000000Z
      handler_name    : Apple Video Media Handler
      encoder         : Animation
      timecode        : 00:00:00;00


  


  Here's the command I run :

  


  ffmpeg -i input.mov -map 0:a? -map 0:s? -pix_fmt argb -b:v 533881667 -maxrate 533881667 -minrate 533881667 -r 29.97 -top 1 -color_range 1 -colorspace 1 -color_primaries 1 -color_trc bt709 -map_metadata 0 -c:a copy -timecode 00:00:00.00 -c:v qtrle -c:s copy output.mov


  


  Output file ffprobe :

  


    Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    creation_time   : 2021-04-13T16:35:16.000000Z
  Duration: 00:00:10.01, start: 0.000000, bitrate: 100126 kb/s
    Stream #0:0: Video: qtrle (rle  / 0x20656C72), argb(progressive), 1920x1080, 100133 kb/s, SAR 1:1 DAR 16:9, 29.97 fps, 29.97 tbr, 11988 tbn, 11988 tbc (default)
    Metadata:
      creation_time   : 2021-04-13T16:35:16.000000Z
      handler_name    : VideoHandler
      encoder         : Lavf58.58.100
      timecode        : 00:00:00;00


  


  As it is visible from the ffprobe from above, I go from :

  


  The Input's file bitrate : 534719 kb/s
to Output bitrate : 100126 kb/s

  


• batch ffmpeg conversion (aspect, crop, and concatenate) and naming based on subfolder

  3 avril 2015, par hordor

  TYIA for any help !

  Seems I have a somewhat complicated, multi-step process. If you can help any part of it that would be appreciated.

  What I hope to accomplish

  1. Example of folder/file is here : https://mega.co.nz/#F !RJRWRLTJ !c6b-z3Vl-Tlh0uGbCflx7Q
  2. I have many subfolders that each contain 7 files from a DVD (originally PAL-encoded I think). I only care about the VTS_01_1.VOB AND VTS_01_2.VOB files. The two files together are one match
  3. The videos are stretched (from 4:3 to 16:9) and letterboxed. I want to undo that
  4. The future title of the final MP4 video should be the name of the folder
  5. BONUS : title of the video should also include the folder before it (e.g. "Friday H2 G1 CAN - BEL.mp4")

  I’d like to do this via batch file because there are a lot of folders.

  What I have done :

  dir/b/s *.vob | findstr /v VIDEO | findstr /v 01_ >list.txt
  
  
  
  @echo off
  
  for %%i in list.txt 
  
  do   
  
    ffmpeg -i VTS_01_1.VOB -aspect 4:3 "%%~pi\v1step1.mp4"
  
    ffmpeg -i vob1.mp4 -vf "crop=704:432:10:72" "%%~pi\v1step2.mp4"
  
    ffmpeg -i vob11.mp4 -c copy "%%~pi\v1step3.ts"
  
    ffmpeg -i VTS_01_2.VOB -aspect 4:3 "%%~pi\v2step1.mp4"
  
    ffmpeg -i vob2.mp4 -vf "crop=704:432:10:72" "%%~pi\v2step2.mp4"
  
    ffmpeg -i vob22.mp4 -bsf h264_mp4toannexb -c copy "%%~pi\v2step3.ts"
  
    ffmpeg -i "concat:v1step3.ts|v2step3.ts" -c copy file.mp4 "%%~pi\Match.mp4"
  
  
  
  @echo on
  
  pause

  Problem with current code

  1. Doesn’t start converting (can’t see error message either)
  2. Doesn’t have the file naming that I want
  3. A lot of steps in conversation - can that be simplified ?
  4. Not sure why it wanted the -bsf command for the second conversion but not the first

  Apologies if I’d made basic mistakes. I’m a big newbie and just to get this far has taken me hours of research. Thanks again !