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• Using FFMPEG : How to do a Scene Change Detection by audio

  9 janvier 2021, par dantedel

  I have a video that has many scenes, within each scene there are several video cuts with and single unique narator.
I'm trying to split the video to individual scenes based on narator. So far only found only a way using select/scene to get timestamps based on scene video changes.

  


  Using FFMPEG : How to do a Scene Change Detection ? with timecode ?

  


  ffmpeg -i input.flv  \
       -filter:v "select='gt(scene,0.4)',showinfo" \
       -f null \
       - 2> ffout


  


  Is there an equivalent way to get the scene changes by examining changes in audio ?

  


• Blown-out speaker ffmpeg sound effect

  8 février 2021, par Shalin Shah

  I was wondering how to do the blown-out speaker effect using ffmpeg where the audio just sounds completely destroyed.

  


  I've tried a bunch of combinations of different commands on ffmpeg and the closest I've gotten is the following (where I use the superequalizer and then make the volume super high) :

  


  import ffmpeg
(
    ffmpeg
    .input('shark.wav')
    .filter("superequalizer", 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20)
    .filter("volume", 10)
    .output('output_speaker.wav')
    .run()
)


  


  I'm using a python wrapper but here's the command line equivalent :

  


  ffmpeg -i shark.wav -af "superequalizer=1b=20:2b=20:3b=20:4b=20:5b=20:6b=20:7b=20:8b=20:9b=20:10b=20:11b=20:12b=20:13b=20:14b=20:15b=20:16b=20:17b=20:18b=20,volume=10" output_speaker.wav


  


  The problem with the above is that it doesn't do anything for files that aren't already super loud (such as recorded audio) and most of the time the audio actually just ends up clipping and then being super soft.

  


  Does anyone have suggestions on how to do this effect ? Thanks !

  


• FFmpeg unexpected behavior using -loop flag

  7 décembre 2020, par all jazz

  Dear hackers of the world !

  


  I've been trying to use the beloved FFmpeg library to create a video from an image loop and audio using the famous Docker FFmpeg image, but it has been driving me crazy not producing the expected results (the results that I get when I run the ffmpeg command with the equivalent version on my Macbook).

  


  Here is the command :

  


  docker run -v $(pwd):$(pwd) -w $(pwd) jrottenberg/ffmpeg:4.3-alpine \
    -y \
    -stats \
    -loop 1 -i files/image.jpg \
    -i files/a.mp3 \
    -c:v libx265 -pix_fmt yuv420p10 \
    -c:a aac \
    -movflags +faststart \
    -shortest \
    -f mp4 test.mp4


  


  It should create a test.mp4 with the provided audio and image that is ready to be uploaded to the unfortunate Youtube.

  


  When I do this, the video seems to be lacking moov atoms (if I try to analyse it). Strangely enough, if I run this two times using the Docker image (overriding the same file), the video file will magically start to work.

  


  I also tried using different ffmpeg os images and versions. It seems that ffmpeg docummentation and code repo could also benefit from some care and love.

  


  What else I could do to get this fixed ?

  


  Here is the output from the console :

  


          -y \
        -stats \
        -loop 1 -i files/image.jpg \
        -i files/a.mp3 \
        -c:v libx265 -pix_fmt yuv420p10 \
        -c:a aac \
        -movflags +faststart \
        -shortest \
        -f mp4 test30.mp4
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 6.4.0 (Alpine 6.4.0)
  configuration: --disable-debug --disable-doc --disable-ffplay --enable-shared --enable-avresample --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-gpl --enable-libass --enable-fontconfig --enable-libfreetype --enable-libvidstab --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libxcb --enable-libx265 --enable-libxvid --enable-libx264 --enable-nonfree --enable-openssl --enable-libfdk_aac --enable-postproc --enable-small --enable-version3 --enable-libbluray --enable-libzmq --extra-libs=-ldl --prefix=/opt/ffmpeg --enable-libopenjpeg --enable-libkvazaar --enable-libaom --extra-libs=-lpthread --enable-libsrt --enable-libaribb24 --extra-cflags=-I/opt/ffmpeg/include --extra-ldflags=-L/opt/ffmpeg/lib
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, image2, from 'files/image.jpg':
  Duration: 00:00:00.04, start: 0.000000, bitrate: 34300 kb/s
    Stream #0:0: Video: mjpeg, gray(bt470bg/unknown/unknown), 500x500 [SAR 240:240 DAR 1:1], 25 fps, 25 tbr, 25 tbn, 25 tbc
Input #1, mp3, from 'files/a.mp3':
  Metadata:
    title           : Visions
    artist          : Hattori Hanzo
    album           : Visions
    encoded_by      : Fission
    encoder         : Lavf58.45.100
    TLEN            : 16039
    track           : 1
  Duration: 00:00:16.04, start: 0.000000, bitrate: 199 kb/s
    Stream #1:0: Audio: mp3, 44100 Hz, stereo, fltp, 191 kb/s
    Stream #1:1: Video: mjpeg, yuvj444p(pc, bt470bg/unknown/unknown), 500x500 [SAR 300:300 DAR 1:1], 90k tbr, 90k tbn, 90k tbc (attached pic)
    Metadata:
      comment         : Other
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> hevc (libx265))
  Stream #1:0 -> #0:1 (mp3 (mp3float) -> aac (native))
Press [q] to stop, [?] for help
x265 [info]: HEVC encoder version 3.1.1+1-04b37fdfd2dc
x265 [info]: build info [Linux][GCC 6.4.0][64 bit] 10bit
x265 [info]: using cpu capabilities: MMX2 SSE2Fast LZCNT SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
x265 [info]: Main 10 profile, Level-3 (Main tier)
x265 [info]: Thread pool created using 8 threads
x265 [info]: Slices                              : 1
x265 [info]: frame threads / pool features       : 3 / wpp(8 rows)
x265 [warning]: Source height < 720p; disabling lookahead-slices
x265 [info]: Coding QT: max CU size, min CU size : 64 / 8
x265 [info]: Residual QT: max TU size, max depth : 32 / 1 inter / 1 intra
x265 [info]: ME / range / subpel / merge         : hex / 57 / 2 / 3
x265 [info]: Keyframe min / max / scenecut / bias: 25 / 250 / 40 / 5.00
x265 [info]: Lookahead / bframes / badapt        : 20 / 4 / 2
x265 [info]: b-pyramid / weightp / weightb       : 1 / 1 / 0
x265 [info]: References / ref-limit  cu / depth  : 3 / off / on
x265 [info]: AQ: mode / str / qg-size / cu-tree  : 2 / 1.0 / 32 / 1
x265 [info]: Rate Control / qCompress            : CRF-28.0 / 0.60
x265 [info]: tools: rd=3 psy-rd=2.00 early-skip rskip signhide tmvp b-intra
x265 [info]: tools: strong-intra-smoothing deblock sao
Output #0, mp4, to 'test30.mp4':
  Metadata:
    encoder         : Lavf58.45.100
    Stream #0:0: Video: hevc (libx265) (hev1 / 0x31766568), yuv420p10le(progressive), 500x500 [SAR 1:1 DAR 1:1], q=-1--1, 25 fps, 12800 tbn, 25 tbc
    Metadata:
      encoder         : Lavc58.91.100 libx265
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
    Stream #0:1: Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s
    Metadata:
      encoder         : Lavc58.91.100 aac
frame=   52 fps=0.0 q=33.0 size=       0kB time=00:00:00.80 bitrate=   0.4kbits/frame=  120 fps=119 q=33.0 size=       0kB time=00:00:03.52 bitrate=   0.1kbits/frame=  190 fps=125 q=33.0 size=       0kB time=00:00:06.33 bitrate=   0.1kbits/frame=  257 fps=127 q=33.0 size=       0kB time=00:00:09.00 bitrate=   0.0kbits/frame=  303 fps=120 q=35.0 size=     256kB time=00:00:10.86 bitrate= 193.0kbits/frame=  373 fps=123 q=36.0 size=     256kB time=00:00:13.65 bitrate= 153.6kbits/[mp4 @ 0x55d481bc6980] Starting second pass: moving the moov atom to the beginning of the file
frame=  432 fps=121 q=36.0 Lsize=     379kB time=00:00:17.16 bitrate= 180.8kbits/s speed= 4.8x
video:107kB audio:255kB subtitle:0kB other streams:0kB global headers:2kB muxing overhead: 4.667185%
x265 [info]: frame I:      2, Avg QP:23.55  kb/s: 8634.80
x265 [info]: frame P:    147, Avg QP:33.00  kb/s: 13.49
x265 [info]: frame B:    283, Avg QP:35.71  kb/s: 8.06
x265 [info]: Weighted P-Frames: Y:0.0% UV:0.0%
x265 [info]: consecutive B-frames: 34.2% 10.1% 20.8% 1.3% 33.6%

encoded 432 frames in 3.56s (121.32 fps), 49.84 kb/s, Avg QP:34.73
[aac @ 0x55d481b23ac0] Qavg: 563.168```