[FFmpeg-user] Concat Creates SlowMo Audio for a Portion of Output

[ace8cjc]

Hi, I have two clips that I am trying to concat.

clip1.dv (raw .dv stream captured via ffmpeg).
clip2.dv (raw .dv stream captured via ffmpeg, trimmed slightly in iMovie HD6, and then exported in fully quality).

When I use ffmpeg to concat the two clips, the output.dv plays back the clip2 portion with super slow-mo audio. The audio of clip1 and the video of both clips plays back fine.

The video source of the two clips is the exact same, and so I know the issue stems from the export of clip2 in iMovie HD6. But, iMovie HD6  handles .dv files natively and the export to full quality should keeps the original codecs.

I understand iMovie HD6 is 3rd party, and so am not asking for help with his software. But, any ideas on how to normalize the audio of clip2 during the concat using ffmpeg?
 
Here is command-line:

ffmpeg -f concat -i mylist.txt -map 0:0 -c copy output.dv
ffmpeg version 5.1.2 Copyright (c) 2000-2022 the FFmpeg developers
  built with Apple clang version 14.0.0 (clang-1400.0.29.202)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/5.1.2_6 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libsvtav1 --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
[dv @ 0x7fa07d904dc0] Detected timecode is invalid
[dv @ 0x7fa07d904dc0] Estimating duration from bitrate, this may be inaccurate
Input #0, concat, from 'mylist.txt':
  Duration: N/A, start: 0.000000, bitrate: 27048 kb/s
  Stream #0:0: Video: dvvideo, yuv411p, 720x480 [SAR 8:9 DAR 4:3], 25000 kb/s, 29.97 fps, 29.97 tbr, 29.97 tbn
  Stream #0:1: Audio: pcm_s16le, 32000 Hz, stereo, s16, 1024 kb/s
  Stream #0:2: Audio: pcm_s16le, 32000 Hz, stereo, s16, 1024 kb/s
Output #0, dv, to 'output.dv':
  Metadata:
    encoder         : Lavf59.27.100
  Stream #0:0: Video: dvvideo, yuv411p, 720x480 [SAR 8:9 DAR 4:3], q=2-31, 25000 kb/s, 29.97 fps, 29.97 tbr, 29.97 tbn
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
[dv @ 0x7fa07d904dc0] Detected timecode is invalid00:58:50.66 bitrate=28770.8kbits/s speed= 243x    
[dv @ 0x7fa07d904dc0] Estimating duration from bitrate, this may be inaccurate
frame=110448 fps=7265 q=-1.0 Lsize=12943125kB time=01:01:25.28 bitrate=28771.2kbits/s speed= 242x    
video:12943125kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%