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• ffmpeg video duration is not equal to duration after hls process

  9 décembre 2022, par Timur Khazhiev

  Problem

  


  For videofile input I preprocess/encode it to libx264. Then I'm trying to cut video into 2 second chunks except last one (last one being < 2 seconds) using hls processing

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  ffmpeg -v error -i video.mp4 -x264-params "keyint=60:min-keyint=60:scenecut=0" 
-hls_time 2 -hls_list_size 0 -hls_segment_filename chunk%03d.ts index.m3u8


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  which follows this problem

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  then looking into index.m3u8 file reveals that sum of all chunks' durations does not add up to original video duration :

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  % ffprobe -loglevel quiet -print_format flat -show_entries format=duration index.m3u8     

format.duration="204.880000"

% ffprobe -loglevel quiet -print_format flat -show_entries format=duration video.mp4 

format.duration="204.892813"


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  Moreover duration of a chunk in index.m3u8 is not the same as in chunk file.

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  % ffprobe -loglevel quiet -print_format flat -show_entries format=duration chunk000.ts

format.duration="2.023222"

% cat index.m3u8
#EXTM3U
#EXT-X-VERSION:3
#EXT-X-TARGETDURATION:2
#EXT-X-MEDIA-SEQUENCE:0
#EXTINF:2.000000,
chunk000.ts
#EXTINF:2.000000,
chunk001.ts
#EXTINF:2.000000,
chunk002.ts
...


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  Misc

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  Used these videos : Me at the zoo and I finally found a useful monorail.

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  OS : macos Monterey 12.3.1 (21E258)

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  ffmpeg version 5.1.2 Copyright (c) 2000-2022 the FFmpeg developers
built with Apple clang version 14.0.0 (clang-1400.0.29.102)
configuration: --prefix=/usr/local/Cellar/ffmpeg/5.1.2 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox
libavutil      57. 28.100 / 57. 28.100
libavcodec     59. 37.100 / 59. 37.100
libavformat    59. 27.100 / 59. 27.100
libavdevice    59.  7.100 / 59.  7.100
libavfilter     8. 44.100 /  8. 44.100
libswscale      6.  7.100 /  6.  7.100
libswresample   4.  7.100 /  4.  7.100
libpostproc    56.  6.100 / 56.  6.100


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  What I tried

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  • Preprocess/transcode video before proceeding with hls

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  • Force keyframes before proceeding with hls

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  • Use 1, 3, 4 seconds chunks

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  • Use different GOP sizes

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  • -hls_flags split_by_time

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  but it leads to same result or very unequal chunks

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  Questions

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  1. Is it ok or I'm missing something ?

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  2. If not, what parameters/options should I use to force chunks to be precisely 2 seconds ?

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• Apply sound effects on a video file

  31 mars 2013, par talhamalik22

  I am a little miss guided here and it seems i am totally lost. I am developing an android app and its core idea is to develop a video recorder and video player that applies some sound effects on the voice of the people or any sound that it records. Sound effect means that if i make a video of a person who is giving some speech then there should be no effect on video but his/her voice should appear like voice in talking tom cat app. I hope you understand the idea. Similar app is Helium Booth you can check it here. I am trying to use libraries like libSonic, libpd and tried to use XUGGLE too.
  Read somewhere that Xuggle is not really developed for mobile devices so left it. Now what i want is that it should apply this effect on voice on the run time i.e while recording the pitch of the sound should be alterd and saved immediately. And what i am getting with these libraries is that i can apply sound effect after video is recorded. So it means i need to rip the audio from the video and then apply the change in pitch and frequency and again concatenate this audio file with the old video file. And i have no idea how to do it.
  Please show me the right approach and tools if possible.

  Regards

• Remove black bars from DV video using ffmpeg [closed]

  2 juillet 2020, par AustinMaxi1750

  I have copied all my Panasonic DV videos (PAL) from the 1990s to my PC as 'dv avi' using Windows movie maker in the original quality (approx 13GB per hour of video).

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  At the time the recordings were made I set the Panasonic camera to 16:9. However searching various forums indicates it was an illusion of 16:9 and black bars were superimposed on the 4:3 picture to give a cinematic feel. I have read also that the DV pixels are not square.

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  As a result all my 16:9 recordings have black bars at the top and bottom when viewed on a 16:9 monitor. The file properties are as follows :

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  Frame width : 720&#xA;Frame height : 576

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  Is there a code in ffmpeg to remove the black bars ?

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  I attach an example of what I have :&#xA;image with black bars

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  and an example of what I want to achieve :&#xA;image without black bars

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  I also want to convert the format without loss of quality so I can watch the videos without the black bars on a modern smart TV. My TV cannot play back DV AVI.

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