roq_dpcm enc: noisy mono audio

[ami_stuff]

​https://trac.ffmpeg.org/raw-attachment/ticket/10178/16_33_M_C0.WA

it looks like a very old regression, 1aeb88b (from 2011) is able to encode mono files in good audio quality

./ffmpeg -i 16_33_M_C0.WA -ar 22050 -y out.roq
ffmpeg version N-109772-gc56f5be678 Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.4.0-1ubuntu1~20.04.1)
  configuration: 
  libavutil      57. 44.100 / 57. 44.100
  libavcodec     59. 63.100 / 59. 63.100
  libavformat    59. 38.100 / 59. 38.100
  libavdevice    59.  8.101 / 59.  8.101
  libavfilter     8. 56.100 /  8. 56.100
  libswscale      6.  8.112 /  6.  8.112
  libswresample   4.  9.100 /  4.  9.100
Input #0, wavarc, from '16_33_M_C0.WA':
  Duration: N/A, start: 0.000000, bitrate: N/A
  Stream #0:0: Audio: wavarc (0CPY / 0x59504330), 33333 Hz, mono, s16p
Stream mapping:
  Stream #0:0 -> #0:0 (wavarc (native) -> roq_dpcm (native))
Press [q] to stop, [?] for help
Output #0, roq, to 'out.roq':
  Metadata:
    encoder         : Lavf59.38.100
  Stream #0:0: Audio: roq_dpcm, 22050 Hz, mono, s16, 178 kb/s
    Metadata:
      encoder         : Lavc59.63.100 roq_dpcm
[wavarc @ 0x5582329d1700] get_buffer() failed=  -0.0kbits/s speed=N/A    
Error while decoding stream #0:0: Invalid data found when processing input
size=     218kB time=00:00:09.96 bitrate= 178.9kbits/s speed= 478x    
video:0kB audio:218kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.003590%

./ffmpeg -i out.roq -y out.wav
ffmpeg version N-109772-gc56f5be678 Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.4.0-1ubuntu1~20.04.1)
  configuration: 
  libavutil      57. 44.100 / 57. 44.100
  libavcodec     59. 63.100 / 59. 63.100
  libavformat    59. 38.100 / 59. 38.100
  libavdevice    59.  8.101 / 59.  8.101
  libavfilter     8. 56.100 /  8. 56.100
  libswscale      6.  8.112 /  6.  8.112
  libswresample   4.  9.100 /  4.  9.100
[roq @ 0x5577da87b440] Estimating duration from bitrate, this may be inaccurate
Input #0, roq, from 'out.roq':
  Duration: 00:00:05.05, start: 0.000000, bitrate: 352 kb/s
  Stream #0:0: Audio: roq_dpcm, 22050 Hz, mono, s16, 352 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (roq_dpcm (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, wav, to 'out.wav':
  Metadata:
    ISFT            : Lavf59.38.100
  Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 22050 Hz, mono, s16, 352 kb/s
    Metadata:
      encoder         : Lavc59.63.100 pcm_s16le
Error demuxing input file 0: Input/output erroreed=N/A    
out.roq: Input/output error
size=     431kB time=00:00:09.96 bitrate= 354.0kbits/s speed=1.32e+03x    
video:0kB audio:431kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.017687%

[Elon Musk]

The version you use is still old. Now libavcodec is 60.X.100

[Elon Musk]

Fixed in 2b4273072dbb1dde2ab4bbbd30b3cef4042fc4fb