Failed to decode the chunk, reason: Decoding failed. ffmpeg returned error code: 183

[0100101101011010]

I frequently run into this error when converting ebooks. Sometimes the chapter still converts to mp3 seemingly without problems; other times, only the first part of it will convert, and mostly it will fail to convert entirely.

2025-06-05 19:44:31,620 - [Worker-87864] - edge_tts_provider.py:103 - generate_audio - WARNING - Failed to decode the chunk, reason: Decoding failed. ffmpeg returned error code: 183

Output from ffmpeg/avlib:

ffmpeg version 7.1.1 Copyright (c) 2000-2025 the FFmpeg developers
  built with Apple clang version 17.0.0 (clang-1700.0.13.3)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/7.1.1_3 --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. 19.101 / 61. 19.101
  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
[cache @ 0x6000018281c0] Inner protocol failed to seekback end : -78
    Last message repeated 1 times
[mp3 @ 0x149704a50] Failed to find two consecutive MPEG audio frames.
[cache @ 0x6000018281c0] Statistics, cache hits:0 cache misses:0
[in#0 @ 0x600000f28a00] Error opening input: Invalid data found when processing input
Error opening input file cache:pipe:0.
Error opening input files: Invalid data found when processing input
, returning a silent chunk.

[p0n1]

Thanks for reporting. Is it a specific e-book, or are all of them having issues? Have you adjusted the worker count parameter instead of using the default?

[0100101101011010]

Thanks, I tried changing the worker count to 8 and 16, at 16 the problem seems to have gone away! Have done about 5 books now with no issues. Before changing the worker count (is the default parameter 1?) it was cropping up with most books I tried.

[p0n1]

OK. I think the default parameter 1 should be more stable. The higher worker count could lead to more issues related with network or rate limits.

I searched the 'ffmpeg returned error code: 183' log on my side and found most of them are just warnings due to empty text processing. So it won't lead to convert failure.

I'm working on improving the edge-tts converting experience in #144.

[p0n1]

Just released https://github.com/p0n1/epub_to_audiobook/releases/tag/v0.8.2 with polished edge tts experience. Feel free to give a try. Any feedback welcomed.

[0100101101011010]

Sorry for the late reply, I haven't converted any books in quite a while. I just tried the latest update with two books using edge-tts and they both worked pretty well. I didn't change the worker count parameter.

For one of the books, weirdly I saw this "no audio received" error in the log for many of the initial chapters of the book. But it usually resolved by attempt like 6 or 7 or something so the entire book was still able to be converted in the end.

WARNING - Error while converting text to speech for [chaptername]_chunk_2_of_2 (attempt 2/12): No audio was received. Please verify that your parameters are correct.

Other than that I haven't noticed any issues at all.

I absolutely love the Web-UI by the way. Makes it much easier to adjust the settings. Thanks for your amazing work!