[flac-dev] 64-bit residuals

Martijn van Beurden mvanb1 at gmail.com
Tue Mar 29 14:57:10 UTC 2022

Op di 29 mrt. 2022 om 11:43 schreef Miroslav Lichvar <mlichvar at redhat.com>:
> The third option makes most sense to me. I don't think we should
> complicate decoders by requiring them to support 64-bit residuals only
> because it's technically possible to encode such a stream.

Would you argue this limitation is imposed on all possible FLAC
streams, or just for PCM inputs with a bit depth up to and including
24? Or should this also apply to 32-bit streams?

A similar problem in the spec represents itself with 32-bit PCM
inputs. When applying stereo decorrelation, a transformation to side a
subframe bps of 33, which is very inconvenient. Should stereo
decorrelation be forbidden for 32 bps inputs?

While these distinctions might seem unimportant and 32-bit streams
folly, there is currently an effort underway to make FLAC and IETF RFC
standard. I think that the decoder of the reference implementation
(libFLAC) should support all features the format has before the
standard becomes final. As the FLAC format has always supported 32 bps
streams but no encoder for these exists, I think this requires some
extra care.

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