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LibAudio: Rescale integer samples correctly in FLAC loader

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The FLAC samples are signed, so we need to rescale them not by their bit
depth, but by half of the bit depth. For example, a 24-bit sample
extends from -2^23 to 2^23-1, and therefore needs to be rescaled by 2^23
to conform to the [-1, 1] double sample range.
This commit is contained in:
kleines Filmröllchen 2021-08-16 22:01:26 +02:00 • committed by Andreas Kling
parent 442aa48a61
commit c974be91ab
1 changed files with 1 additions and 2 deletions
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3
Userland/Libraries/LibAudio/FlacLoader.cpp
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@ -414,8 +414,7 @@ void FlacLoaderPlugin::next_frame()
VERIFY(left.size() == right.size());
// TODO: find the correct rescale offset
double sample_rescale = static_cast<double>(1 << pcm_bits_per_sample(m_current_frame->bit_depth));
double sample_rescale = static_cast<double>(1 << (pcm_bits_per_sample(m_current_frame->bit_depth) - 1));
dbgln_if(AFLACLOADER_DEBUG, "Sample rescaled from {} bits: factor {:.1f}", pcm_bits_per_sample(m_current_frame->bit_depth), sample_rescale);
m_current_frame_data.clear_with_capacity();