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• FFMPEG - modify only part of video with select filter

  28 janvier 2023, par Compact

  I have a video file - an NTSC DVD rip. I want to convert it into PAL DVD. The problem with that NTSC DVD is that it's a mixture of telecined content, true progressive 29.97 content, true interlaced content at 29.97 fps. The problem is with the true interlaced content - it's sometimes encoded as top field first and sometimes as bottom field first...

  


  To keep quality as much as possible, I would like remove telecined frames, but keep those interlaced sequences and turn them to 25 fps top field first. This is where the problem arises.

  


  I tried to make filter_complex chain with two select filters, where I reverse the fields for bottom field first frames, but the video is not encoding at all when I do that.

  


  Here is an example filter chain I tried to make - I've made a lot of iterations of something similar, using select or metadata select to no avail. I guess I don't understand how select and metadata select filters work. And I don't know how to do what I want.

  


  ffmpeg -i "input" -flags +ildct+ilme \
-filter_complex\
[0:v]idet,setparams=color_primaries=smpte170m:color_trc=bt709:colorspace=smpte170m \
,metadata=select:key=lavfi.idet.single.current_frame:value=bff:function=same_str,phase=b[bot];\[bot]metadata=select:key=lavfi.idet.single.current_frame:value=tff:function=same_str\
,fieldmatch=mode=pcn_ub:combmatch=full,decimate[tff];\
[tff]metadata=select:key=lavfi.idet.single.current_frame:value=progressive:function=same_str\
,fps=24000/1001[v1];[v1]select,setfield=tff[v]"


  


  If all of the interlaced content was top field first, I could simply do something similar to this :

  


  ffmpeg -i "input" -flags +ildct+ilme \
-filter:v "dejudder,fps=30000/1001,fieldmatch=mode=pcn_ub:combmatch=full,\
decimate,settb=1/25000,setpts=N/(25*TB),setfield=tff,setparams=field_mode=tff"


  


  Is that possible with ffmpeg ? To just modify a part of video and then modify it whole, including with the previous modification ?

  


• How can i crop part of a video while recording from desktop in real time using ffmpeg ? [on hold]

  28 juillet 2017, par daniel llee

  I’m using this line to record from the desktop to a video file :

  ffmpeg -f gdigrab -framerate 24 -i desktop -preset ultrafast -pix_fmt yuv420p out.mp4

  But this will record the whole desktop. Is there any way to record in real time only specific area/part of the desktop ?

  And this is how i’m using the ffmpeg with winforms :

  using System;  
  
  using System.Collections.Generic;  
  
  using System.Linq;  
  
  using System.Text;  
  
  using System.Threading.Tasks;  
  
  using System.IO;  
  
  using System.Diagnostics;  
  
  
  
  namespace Ffmpeg_App  
  
  {  
  
      class Ffmpeg  
  
      {  
  
          Process process;  
  
  
  
          public void Start(string FileName, int Framerate)  
  
          {  
  
              process = new System.Diagnostics.Process();  
  
              process.StartInfo.FileName = @"D:\ffmpegx86\ffmpeg.exe"; // Change the directory where ffmpeg.exe is.  
  
              process.EnableRaisingEvents = false;  
  
              process.StartInfo.WorkingDirectory = @"D:\ffmpegx86"; // The output directory  
  
              process.StartInfo.Arguments = @"-f gdigrab -framerate " + Framerate + " -i desktop -preset ultrafast -                                                                     pix_fmt yuv420p " + FileName;  
  
              process.Start();  
  
              process.StartInfo.UseShellExecute = false;  
  
              process.StartInfo.CreateNoWindow = false;  
  
              Close();  
  
          }  
  
  
  
          public void Close()  
  
          {  
  
              process.Close();  
  
          }  
  
      }  
  
  }  

• ffmpeg segments only the first part of my audio file

  30 juin 2012, par hammat

  I'm implementing a http live streaming server to send audio file to iOS devices.
  No problem with Apple's tools, mediafilesegmenter, my files are valid and it works fine.

  I'm trying now to segment the same file using ffmpeg. I've downloaded the last stable version which is the 0.10.2 for now.

  Here is how I try to segment my mp3 file :

  ./ffmpeg -re -i input.mp3 -f segment -segment_time 10 -segment_list outputList.m3u8 -acodec libmp3lame -map 0 output%03d.mp3

  It starts the mapping like expected but finish with only one .mp3 file.

  Did I miss something in the process ?
  Thanks in advance.

  edit

  Ok here is my latest command line :

  ffmpeg -i input.mp3 -c:a libmp3lame -b:a 128k -map 0:0 -f segment -segment_time 10 -segment_list outputlist.m3u8 -segment_format mp3 'output%03d.mp3'

  It still gives me only one file but the file is the hole song, not only one part.
  Here is the output of ffmpeg :

  ffmpeg version 0.10.2 Copyright (c) 2000-2012 the FFmpeg developers 
  
  built on Apr 20 2012 07:08:29 with gcc 4.5.2   
  
  configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-libmp3lame   
  
      libavutil      51. 35.100 / 51. 35.100   
  
      libavcodec     53. 61.100 / 53. 61.100   
  
      libavformat    53. 32.100 /
  
          53. 32.100   
  
      libavdevice    53.  4.100 / 53.  4.100   
  
      libavfilter     2. 61.100 /  2. 61.100   
  
      libswscale      2.  1.100 /  2.  1.100   
  
      libswresample   0.  6.100 /  0.  6.100   
  
      libpostproc    52.  0.100 /  52.  0.100 
  
      [mp3 @ 0x8e4f120] max_analyze_duration 5000000 reached at 5015510
  
  Input #0, mp3, from 'BeachHouse-Myth.mp3':   
  
      Metadata:
  
              title           : Myth
  
              artist          : Beach House
  
              track           : /
  
              album           : Bloom
  
              disc            : /
  
              genre           : Alternative
  
              TSRC            : USSUB1296501   
  
      Duration: 00:04:18.69, start: 0.000000, bitrate: 320 kb/s
  
              Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16, 320 kb/s Output #0, segment, to 'stream%03d.mp3':   Metadata:
  
              title           : Myth
  
              artist          : Beach House
  
              track           : /
  
              album           : Bloom
  
              disc            : /
  
              genre           : Alternative
  
              TSRC            : USSUB1296501
  
              encoder         : Lavf53.32.100
  
              Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16, 128 kb/s
  
  Stream mapping:   
  
      Stream #0:0 -> #0:0 (mp3 -> libmp3lame) 
  
      Press [q] to stop, [?] for help 
  
      Truncating packet of size 1024 to 105ate=   0.0kbits/s    
  
      Truncating packet of size 1024 to 1 
  
      size=       0kB time=00:04:18.71 bitrate=   0.0kbits/s     video:0kB audio:4042kB global headers:0kB muxing overhead -100.000000%