balrogg: lossless Vorbis/Opus recompressor

[_contextmodel]

v1.2 is now attached. It should be markedly faster.

            parallel (79.3 MB, 1047 files)    newmusic_piano3.ogg (2.5 MB)
   tool  |  e/time |     ratio (size) | mem |  e/time |    ratio (size) | mem
 1.2  -1 |  1.63 s | 90.4% (75,274kB) | 15M |  0.42 s | 83.3% (2,221kB) |  7M
      -2 |  1.85 s | 89.2% (74,276kB) | 15M |  0.77 s | 79.4% (2,118kB) |  7M
      -3 |  1.97 s | 89.0% (74,052kB) | 17M |  0.82 s | 79.2% (2,113kB) |  8M
      -4 |  2.06 s | 88.6% (73,761kB) | 17M |  0.90 s | 78.9% (2,106kB) |  8M
      -5 |  4.24 s | 88.3% (73,524kB) | 17M |  2.78 s | 78.6% (2,095kB) |  9M
      -6 |  6.31 s | 88.2% (73,438kB) | 17M |  4.55 s | 78.3% (2,089kB) | 10M
      -7 |  8.39 s | 88.2% (73,435kB) | 17M |  6.25 s | 78.3% (2,089kB) | 11M
      -8 | 10.65 s | 88.2% (73,428kB) | 17M |  8.00 s | 78.3% (2,089kB) | 11M
      -9 | 15.11 s | 88.2% (73,428kB) | 17M | 11.73 s | 78.3% (2,089kB) | 11M

 1.1  -1 |  0.93 s | 90.4% (75,270kB) | 11M |  0.45 s | 83.3% (2,221kB) |  6M
      -2 |  1.30 s | 89.2% (74,272kB) | 11M |  0.84 s | 79.4% (2,118kB) |  7M
      -3 |  1.41 s | 88.9% (74,048kB) | 13M |  0.90 s | 79.2% (2,113kB) |  8M
      -4 |  1.64 s | 88.6% (73,757kB) | 13M |  0.96 s | 78.9% (2,106kB) |  8M
      -5 |  4.39 s | 88.3% (73,520kB) | 13M |  3.01 s | 78.6% (2,095kB) | 10M
      -6 |  6.89 s | 88.2% (73,434kB) | 13M |  5.00 s | 78.3% (2,089kB) | 10M
      -7 |  9.44 s | 88.2% (73,431kB) | 13M |  6.84 s | 78.3% (2,089kB) | 10M
      -8 | 11.92 s | 88.2% (73,424kB) | 13M |  8.56 s | 78.3% (2,089kB) | 10M
      -9 | 16.75 s | 88.2% (73,424kB) | 13M | 12.22 s | 78.3% (2,089kB) | 10M

 1.0  -1 |  0.92 s | 90.4% (75,238kB) | 37M |  0.43 s | 83.3% (2,221kB) | 12M
      -2 |  1.25 s | 89.2% (74,241kB) | 37M |  0.86 s | 79.4% (2,118kB) | 12M
      -3 |  1.40 s | 88.9% (74,017kB) | 38M |  0.91 s | 79.2% (2,113kB) | 13M
      -4 |  1.63 s | 88.6% (73,726kB) | 38M |  1.00 s | 78.9% (2,105kB) | 13M
      -5 |  5.68 s | 88.3% (73,489kB) | 46M |  3.13 s | 78.6% (2,095kB) | 46M
      -6 |  9.66 s | 88.2% (73,404kB) | 47M |  5.07 s | 78.3% (2,089kB) | 46M
      -7 | 13.30 s | 88.2% (73,401kB) | 47M |  7.00 s | 78.3% (2,089kB) | 46M
      -8 | 16.91 s | 88.2% (73,394kB) | 47M |  9.02 s | 78.3% (2,089kB) | 46M
      -9 | 24.04 s | 88.2% (73,394kB) | 48M | 13.08 s | 78.3% (2,089kB) | 48M

Mean of 5 on AMD Ryzen 9 5950X. v1.2: calls fsync() and FlushFileBuffers() for
more durable I/O handling, explaining the minor parallel regression.