parse_riff_wave read every fmt chunk as a WAVEFORMATEX. XMA1 (tag 0x0165) is
not one, so audio info reported the disc s movie voices as 16 channels,
4310 Hz, 2-bit: 16 is wBitsPerSample read as a channel count and 4310 is
wEncodeOptions (0x10d6) read as a sample rate. This misled me earlier in the
session and I recorded it as a limitation before finding the cause.
XMA1 carries XMAWAVEFORMAT followed by one XMASTREAMFORMAT per stream. The
reader now branches on the tag and reads bits at +2, PsuedoBytesPerSec at +12,
SampleRate at +16 and Channels at +29. The same three files now report 2
channels, 48000 Hz, 16-bit.
The consequence worth having: this crate has no XMA decoder, and
data_bytes / PsuedoBytesPerSec is the only route to a duration. Checked against
durations decoded independently by the port:
ADV presentation 1 137.34 s declared 137.324 s decoded +0.012 percent
ADV presentation 2 137.33 s declared 137.324 s decoded +0.004 percent
S00A presentation 1 93.71 s declared 93.694 s decoded +0.017 percent
So the corpus can now get XMA1 durations off the disc without a decoder, which
is a capability I had written down as absent. It is a declared rate rather than
a measurement of the samples, and the CLI labels it as such.
Regression test pins the real on-disc header bytes and asserts the duration
against the independently decoded 137.324 s. 115 lib tests and 3 media disc
tests pass.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QsEPXWVaEpyfudtR6re1Pd
a98a66190e