[FFmpeg-user] What am I doing wrong with xfade

Sat Sep 10 18:24:50 EEST 2022

I have to concatenate about 30 videos together with xfade. Because I
did not mange to find a way to do that in one command I wrote a script
that does 1 and 2 to 1-2, 3 and 4 to 3-4, 4 and 5 to 5-6, …
Then 1-2 and 3-4 to 1-4, 5-6 and 7-8 to 5-8, …
Etcetera.

But it seems that in every iteration the audio goes out of sync with
about one second.

Example of one of the commands:
    nice -n 10 ionice -c3 time ffmpeg -y \
      -i snellerDanDeWind.mkv            \
      -i deFinale.mkv                    \
      -vcodec libx264                    \
      -crf 26                            \
      -acodec libmp3lame                 \
      -qscale:a 9                        \
      -preset veryfast                   \
      -filter_complex
    'xfade=transition=slidedown:duration=4:offset=126.083000;acrossfade=d=4' \
    snellerDanDeWind-deFinale.mkv

What am I doing wrong?

The first part of the log for this command:
    ffmpeg version 4.3.4-0+deb11u1 Copyright (c) 2000-2021 the FFmpeg developers
      built with gcc 10 (Debian 10.2.1-6)
      configuration: --prefix=/usr --extra-version=0+deb11u1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-pocketsphinx --enable-libmfx --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
      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, matroska,webm, from 'snellerDanDeWind.mkv':
      Metadata:
        ENCODER         : Lavf58.45.100
      Duration: 00:02:10.08, start: 0.000000, bitrate: 4829 kb/s
        Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 1k tbn, 50 tbc (default)
        Metadata:
          ENCODER         : Lavc58.91.100 libx264
          DURATION        : 00:02:10.083000000
        Stream #0:1: Audio: vorbis, 48000 Hz, stereo, fltp (default)
        Metadata:
          ENCODER         : Lavc58.91.100 libvorbis
          DURATION        : 00:02:10.003000000
    Input #1, matroska,webm, from 'deFinale.mkv':
      Metadata:
        ENCODER         : Lavf58.45.100
      Duration: 00:12:10.44, start: 0.000000, bitrate: 3210 kb/s
        Stream #1:0: Video: h264 (High), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 1k tbn, 50 tbc (default)
        Metadata:
          ENCODER         : Lavc58.91.100 libx264
          DURATION        : 00:12:10.443000000
        Stream #1:1: Audio: vorbis, 48000 Hz, stereo, fltp (default)
        Metadata:
          ENCODER         : Lavc58.91.100 libvorbis
          DURATION        : 00:12:10.003000000
    Stream mapping:
      Stream #0:0 (h264) -> xfade:main
      Stream #0:1 (vorbis) -> acrossfade:crossfade0
      Stream #1:0 (h264) -> xfade:xfade
      Stream #1:1 (vorbis) -> acrossfade:crossfade1
      xfade -> Stream #0:0 (libx264)
      acrossfade -> Stream #0:1 (libmp3lame)
    Press [q] to stop, [?] for help
    [libx264 @ 0x55f112f35200] using SAR=1/1
    [libx264 @ 0x55f112f35200] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX XOP FMA3 BMI1
    [libx264 @ 0x55f112f35200] profile High 4:4:4 Predictive, level 4.0, 4:4:4, 8-bit
    [libx264 @ 0x55f112f35200] 264 - core 160 r3011 cde9a93 - H.264/MPEG-4 AVC codec - Copyleft 2003-2020 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=2 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=6 threads=6 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=1 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=10 rc=crf mbtree=1 crf=26.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
    Output #0, matroska, to 'snellerDanDeWind-deFinale.mkv':
      Metadata:
        encoder         : Lavf58.45.100
        Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv444p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 25 fps, 1k tbn, 25 tbc (default)
        Metadata:
          encoder         : Lavc58.91.100 libx264
        Side data:
          cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
        Stream #0:1: Audio: mp3 (libmp3lame) (U[0][0][0] / 0x0055), 48000 Hz, stereo, fltp (default)
        Metadata:
          encoder         : Lavc58.91.100 libmp3lame

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof