Error opening *.wav file with f32/i32 format

[takeshi87]

Hi

In version v0.5.4-rc0 many of the baseband files recorded using SDR++ stopped working. It seems to affect the wav files recorded using float32 and int32 types.

An example recording:
wav file

An attempt to open this files results in:

[bvernoux]

Two things were fixed:

• v0.5.4-rc0 had an alignment check that was too strict: it required the data offset to be aligned to the full sample size (e.g., 8 bytes for complex<float>) instead of just the scalar alignment.
  SDR++ writes a standard 44-byte WAV header with codec 1 (PCM) for int16/int32 and codec 3 (IEEE float) for float32, and 44 isn't a multiple of 8, so rc0 rejected it.
• v0.5.4-rc1 now checks against alignof(scalar) (4 for float and int32, 2 for int16), which 44 satisfies. The check is still there because misaligned scalar reads are UB and crash on strict-alignment archs like ARM, but it now only triggers on genuinely misaligned offsets. If you ever hit that, the WAV needs to be rewritten with a properly-aligned data offset.
• v0.5.4-rc1 also adds support for basic WAVE_FORMAT_EXTENSIBLE (0xFFFE), where the real codec (PCM or IEEE float) is stored in the first 4 bytes of the SubFormat GUID.
  SDR++ doesn't use this, but other SDR apps do (e.g., sox-wrapped float WAVs from gqrx, or recorders that emit >2 channels or non-standard bit depths), so v0.5.4-rc0 rejected those too.