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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 ?

  


• pydub returning zero byte file when I try to export part of an Mp3

  25 janvier 2023, par tom f

  I'm sharing this for posterity, since I already figured out the answer. I'm trying to create preview snippets of MP3 files with pydub in Python, but when I ran the export the files were always zero bytes in size.

  



  example :

  



  from pydub import AudioSegment    

sound = AudioSegment.from_mp3("preview_temp/n/1/mp3/01_Beyond_and_Into_the_Ultimate.mp3")

# len() and slicing are in milliseconds
halfway_point = len(sound) / 2

second_half = sound[halfway_point:]
print second_half
second_half.export("preview_temp/n/1/prev/prev_test.mp3", format="mp3", bitrate="192k")


  



  I verified the source file existed and was accessible. My inkling was this had something to do with ffmpeg. It was installed properly, but then I came across this on the pydub github :

  



  


  You may use libav or ffmpeg. libav is recommended.

  


  



  The pydub developer runs through installation on several platforms on the github wiki. I'm sharing it here to make it easier for folks to find, though.

  


• How do I add a text for the 1st 30 seconds inside a filter_complex expression for each video part ?

  30 décembre 2022, par PirateApp

  I am generating a video grid using the following filter_complex command

  


  ffmpeg
     -i v_nimble_guardian.mkv -i macko_nimble_guardian.mkv -i ghost_nimble_guardian_1.mp4 -i nano_nimble_guardian.mkv
     -filter_complex "
         nullsrc=size=3840x2160 [base];
         [0:v] trim=start=39.117000,setpts=PTS-STARTPTS, scale=1920x1080 [upperleft];
         [1:v] trim=start=40.483000,setpts=PTS-STARTPTS, scale=1920x1080 [upperright];
         [2:v] trim=start=32.416471,setpts=PTS-STARTPTS, scale=1920x1080 [lowerleft];
         [3:v] trim=start=28.100000,setpts=PTS-STARTPTS, scale=1920x1080 [lowerright];
         [3:a] atrim=start=28.100000,asetpts=PTS-STARTPTS[outa];
         [base][upperleft] overlay=shortest=1 [tmp1];
         [tmp1][upperright] overlay=shortest=1:x=1920 [tmp2];
         [tmp2][lowerleft] overlay=shortest=1:y=1080 [tmp3];
         [tmp3][lowerright] overlay=shortest=1:x=1920:y=1080[v]
     "
     -map "[v]" -map "[outa]" -c:v libx264 -crf 17 -shortest -t 880 output4k.mkv


  


  How do I text to this video grid that will appear with a fade in at 10 seconds, stay for 30 seconds and then fade out ?

  


  

  


  What I tried ?

  


  ffmpeg
     -i v.mkv -i macko_nimble_guardian.mkv -i ghost_nimble_guardian_subtle_arrow_1.mp4 -i nano_nimble_guardian.mkv
     -filter_complex "
         nullsrc=size=1920x1080 [base];
         drawtext=text='Summer Video':enable='between(t,10,30)'[fg];
         [0:v] trim=start=39.117000,setpts=PTS-STARTPTS, scale=960x540 [upperleft];
         [1:v] trim=start=40.483000,setpts=PTS-STARTPTS, scale=960x540 [upperright];
         [2:v] trim=start=32.416471,setpts=PTS-STARTPTS, scale=960x540 [lowerleft];
         [3:v] trim=start=28.100000,setpts=PTS-STARTPTS, scale=960x540 [lowerright];
         [3:a] atrim=start=28.100000,asetpts=PTS-STARTPTS[outa];
         [base][upperleft] overlay=shortest=1 [tmp1];
         [tmp1][upperright] overlay=shortest=1:x=960 [tmp2];
         [tmp2][lowerleft] overlay=shortest=1:y=540 [tmp3];
         [tmp3][lowerright] overlay=shortest=1:x=960:y=540[v]
     "
     -map "[v]" -map "[outa]" -c:v libx264 -shortest -t '30' output2.mkv


  


  It gives me an error

  


  [Parsed_drawtext_1 @ 0x600002bdc420] Using "/System/Library/Fonts/Supplemental/Verdana.ttf"
Filter drawtext:default has an unconnected output