mp3float Header missing vs. Conversion failed!

[Jozef Chutka]

Using ffmpeg 7.1 re-encoding an mp3 prints errors like

ffmpeg -i input.mp3 out.mp3 -y

ffmpeg version 7.1 Copyright (c) 2000-2024 the FFmpeg developers
  built with Apple clang version 16.0.0 (clang-1600.0.26.4)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/7.1_4 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --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 --enable-audiotoolbox --enable-neon
  libavutil      59. 39.100 / 59. 39.100
  libavcodec     61. 19.100 / 61. 19.100
  libavformat    61.  7.100 / 61.  7.100
  libavdevice    61.  3.100 / 61.  3.100
  libavfilter    10.  4.100 / 10.  4.100
  libswscale      8.  3.100 /  8.  3.100
  libswresample   5.  3.100 /  5.  3.100
  libpostproc    58.  3.100 / 58.  3.100
[mp3 @ 0x14ef2f8f0] Estimating duration from bitrate, this may be inaccurate
Input #0, mp3, from 'input.mp3':
  Metadata:
    major_brand     : dash
    minor_version   : 0
    compatible_brands: iso6mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:55.43, start: 0.000000, bitrate: 128 kb/s
  Stream #0:0: Audio: mp3 (mp3float), 44100 Hz, stereo, fltp, 128 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (mp3 (mp3float) -> mp3 (libmp3lame))
Press [q] to stop, [?] for help
Output #0, mp3, to 'out.mp3':
  Metadata:
    major_brand     : dash
    minor_version   : 0
    compatible_brands: iso6mp41
    TSSE            : Lavf61.7.100
  Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp
      Metadata:
        encoder         : Lavc61.19.100 libmp3lame
[mp3float @ 0x14ef3bed0] Header missing
[aist#0:0/mp3 @ 0x14ef31380] [dec:mp3float @ 0x14ef3b850] Error submitting packet to decoder: Invalid data found when processing input
[out#0/mp3 @ 0x14ef307b0] video:0KiB audio:856KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: 0.039363%
size=     856KiB time=00:00:54.75 bitrate= 128.1kbits/s speed= 126x    

And it produces out.mp3 (876805 bytes) with exit code 0

Now a slightly modified command using filter_complex prints different error which look almost like the process failed

ffmpeg -filter_complex "amovie=input.mp3" out.mp3 -y

ffmpeg version 7.1 Copyright (c) 2000-2024 the FFmpeg developers
  built with Apple clang version 16.0.0 (clang-1600.0.26.4)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/7.1_4 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --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 --enable-audiotoolbox --enable-neon
  libavutil      59. 39.100 / 59. 39.100
  libavcodec     61. 19.100 / 61. 19.100
  libavformat    61.  7.100 / 61.  7.100
  libavdevice    61.  3.100 / 61.  3.100
  libavfilter    10.  4.100 / 10.  4.100
  libswscale      8.  3.100 /  8.  3.100
  libswresample   5.  3.100 /  5.  3.100
  libpostproc    58.  3.100 / 58.  3.100
[mp3 @ 0x155f2fbd0] Estimating duration from bitrate, this may be inaccurate
Stream mapping:
  amovie:out0 -> Stream #0:0 (libmp3lame)
Press [q] to stop, [?] for help
[mp3 @ 0x155f32c20] Estimating duration from bitrate, this may be inaccurate
Output #0, mp3, to 'out.mp3':
  Metadata:
    TSSE            : Lavf61.7.100
  Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp
      Metadata:
        encoder         : Lavc61.19.100 libmp3lame
[mp3float @ 0x155f33b40] Header missing
[fc#0 @ 0x155f2e9e0] Error requesting a frame from the filtergraph: Invalid data found when processing input
[fc#0 @ 0x155f2e9e0] Error sending frames to consumers: Invalid data found when processing input
[fc#0 @ 0x155f2e9e0] Task finished with error code: -1094995529 (Invalid data found when processing input)
[fc#0 @ 0x155f2e9e0] Terminating thread with return code -1094995529 (Invalid data found when processing input)
[out#0/mp3 @ 0x155f392e0] video:0KiB audio:856KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: 0.028752%
size=     856KiB time=00:00:54.75 bitrate= 128.1kbits/s speed= 129x    
Conversion failed!

And produced out.mp3 is only 876712 bytes and exit code 183.

I wonder what is happening here? Why these two similar commands produce different output, one that appears as success and the other one as a failure?

I actually need to run filter_complex b/c there are many filters I need to apply etc. So is there any magic flag/filter/custom decoder I can apply to fix the problem?

Attaching the input.mp3