interplayacm decoder produces errors

[Sam.]

1) What you were trying to accomplish

I am trying to transcode an interplayacm ACM file to a pcm_s16le WAV file.

2) The problem you encountered

I have encountered an error while decoding the interplayacm audio format. I get this error with some but not all ACM files I have tested. The game this file came with and legacy decoders can properly decode and play the file, so the file itself is not corrupt. I am happy to help debug this issue in any way I am able, including providing additional sample files that do and do not produce this error and testing potential fixes. The error in question includes:

Error while decoding stream #0:0: Invalid data found when processing input
Last message repeated 20 times
[interplayacm @ 00000273542efa80] Too many errors when draining, this is a bug. Stop draining and force EOF.
Error while decoding stream #0:0: Internal bug, should not have happened

3) The exact command line you were using

ffmpeg.exe -report -v 9 -loglevel 99 -i interplayacm_decoder_produces_error__Bc1a3.acm Bc1a3_ffmpeg.wav

4) The full, uncut console output

ffmpeg started on 2020-07-22 at 17:33:16
Report written to "ffmpeg-20200722-173316.log"
Log level: 99
ffmpeg version git-2020-07-16-d11cc74 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.3.1 (GCC) 20200621
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libgsm --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 55.100 / 56. 55.100
  libavcodec     58. 96.100 / 58. 96.100
  libavformat    58. 48.100 / 58. 48.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
Splitting the commandline.
Reading option '-report' ... matched as option 'report' (generate a report) with argument '1'.
Reading option '-v' ... matched as option 'v' (set logging level) with argument '9'.
Reading option '-loglevel' ... matched as option 'loglevel' (set logging level) with argument '99'.
Reading option '-i' ... matched as input url with argument 'interplayacm_decoder_produces_error__Bc1a3.acm'.
Reading option 'Bc1a3_ffmpeg.wav' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option report (generate a report) with argument 1.
Applying option v (set logging level) with argument 9.
Successfully parsed a group of options.
Parsing a group of options: input url interplayacm_decoder_produces_error__Bc1a3.acm.
Successfully parsed a group of options.
Opening an input file: interplayacm_decoder_produces_error__Bc1a3.acm.
[NULL @ 0000023f4ec1d640] Opening 'interplayacm_decoder_produces_error__Bc1a3.acm' for reading
[file @ 0000023f4ec1e740] Setting default whitelist 'file,crypto,data'
Probing acm score:66 size:2048
[acm @ 0000023f4ec1d640] Format acm probed with size=2048 and score=66
[acm @ 0000023f4ec1d640] Before avformat_find_stream_info() pos: 14 bytes read:32768 seeks:0 nb_streams:1
[acm @ 0000023f4ec1d640] parser not found for codec interplayacm, packets or times may be invalid.
[acm @ 0000023f4ec1d640] All info found
[acm @ 0000023f4ec1d640] stream 0: start_time: 0 duration: 3.62358
[acm @ 0000023f4ec1d640] format: start_time: 0 duration: 3.62358 (estimate from stream) bitrate=143 kb/s
[acm @ 0000023f4ec1d640] After avformat_find_stream_info() pos: 14 bytes read:32768 seeks:0 frames:0
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, acm, from 'interplayacm_decoder_produces_error__Bc1a3.acm':
  Duration: 00:00:03.62, start: 0.000000, bitrate: 143 kb/s
    Stream #0:0, 0, 1/22050: Audio: interplayacm, 22050 Hz, stereo, s16
Successfully opened the file.
Parsing a group of options: output url Bc1a3_ffmpeg.wav.
Successfully parsed a group of options.
Opening an output file: Bc1a3_ffmpeg.wav.
[file @ 0000023f4ec233c0] Setting default whitelist 'file,crypto,data'
Successfully opened the file.
Stream mapping:
  Stream #0:0 -> #0:0 (interplayacm (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
[acm @ 0000023f4ec1d640] parser not found for codec interplayacm, packets or times may be invalid.
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
detected 8 logical cores
[graph_0_in_0_0 @ 0000023f4ecb3dc0] Setting 'time_base' to value '1/22050'
[graph_0_in_0_0 @ 0000023f4ecb3dc0] Setting 'sample_rate' to value '22050'
[graph_0_in_0_0 @ 0000023f4ecb3dc0] Setting 'sample_fmt' to value 's16'
[graph_0_in_0_0 @ 0000023f4ecb3dc0] Setting 'channel_layout' to value '0x3'
[graph_0_in_0_0 @ 0000023f4ecb3dc0] tb:1/22050 samplefmt:s16 samplerate:22050 chlayout:0x3
[format_out_0_0 @ 0000023f4ecb52c0] Setting 'sample_fmts' to value 's16'
[AVFilterGraph @ 0000023f4ec26480] query_formats: 4 queried, 9 merged, 0 already done, 0 delayed
Output #0, wav, to 'Bc1a3_ffmpeg.wav':
  Metadata:
    ISFT            : Lavf58.48.100
    Stream #0:0, 0, 1/22050: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 22050 Hz, stereo, s16, 705 kb/s
    Metadata:
      encoder         : Lavc58.96.100 pcm_s16le
[interplayacm @ 0000023f4ec1fa80] Multiple frames in a packet.
Error while decoding stream #0:0: Invalid data found when processing input
    Last message repeated 20 times
[interplayacm @ 0000023f4ec1fa80] Too many errors when draining, this is a bug. Stop draining and force EOF.
Error while decoding stream #0:0: Internal bug, should not have happened
[out_0_0 @ 0000023f4ecb26c0] EOF on sink link out_0_0:default.
No more output streams to write to, finishing.
size=     316kB time=00:00:03.66 bitrate= 705.8kbits/s speed=51.9x
video:0kB audio:316kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.024105%
Input file #0 (interplayacm_decoder_produces_error__Bc1a3.acm):
  Input stream #0:0 (audio): 64 packets read (64767 bytes); 79 frames decoded (80896 samples);
  Total: 64 packets (64767 bytes) demuxed
Output file #0 (Bc1a3_ffmpeg.wav):
  Output stream #0:0 (audio): 79 frames encoded (80896 samples); 79 packets muxed (323584 bytes);
  Total: 79 packets (323584 bytes) muxed
79 frames successfully decoded, 22 decoding errors
[AVIOContext @ 0000023f4ec23500] Statistics: 4 seeks, 4 writeouts
[AVIOContext @ 0000023f4ec269c0] Statistics: 64781 bytes read, 0 seeks

5) Sufficient information, including any required input files, to reproduce the bug and confirm a potential fix.

See interplayacm_decoder_produces_error__Bc1a3.ACM for an ACM file that produces the error.
See Bc1a3_ffmpeg.wav for the file produced by ffmpeg using the above listed command (despite the errors).
See Bc1a3_acm2wav.wav for the original file decoded to a WAV file by a legacy decoder.

[Elon Musk]

Please provide name of legacy decoder.

[Sam.]

Interplay ACM to WAV converter v1.32, (c) 1999-2003 ABel [TeamX]

acm2wav.exe
I can provide a download link to a precompiled windows binary, but AFAIK the source code is not publically available online.

Near Infinity can also decompress it to a WAV file. The results are identical to acm2wav.exe except that it leaves out the extraneous LIST chunk at the end. It is open source (Java): ​https://github.com/NearInfinityBrowser/NearInfinity/blob/devel/src/org/infinity/resource/sound/AcmBuffer.java

[Elon Musk]

Fixed in a590dfc242620fc7bd628e9351cbcf940da0e965