From 90b835758fb1584c232ec134f31371be201dc5e9 Mon Sep 17 00:00:00 2001
From: MerryMage <MerryMage@users.noreply.github.com>
Date: Sun, 25 Feb 2018 12:42:15 +0000
Subject: [PATCH] decode: Fix PCM8 decoding
Signal range is -32767 to 32768, not -127 to 128.
---
src/audio_core/codec.cpp | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/src/audio_core/codec.cpp b/src/audio_core/codec.cpp
index 81fd44b20..b91979c2e 100644
--- a/src/audio_core/codec.cpp
+++ b/src/audio_core/codec.cpp
@@ -79,26 +79,24 @@ StereoBuffer16 DecodeADPCM(const u8* const data, const size_t sample_count,
return ret;
}
-static s16 SignExtendS8(u8 x) {
- // The data is actually signed PCM8.
- // We sign extend this to signed PCM16.
- return static_cast<s16>(static_cast<s8>(x));
-}
-
StereoBuffer16 DecodePCM8(const unsigned num_channels, const u8* const data,
const size_t sample_count) {
ASSERT(num_channels == 1 || num_channels == 2);
+ const auto decode_sample = [](u8 sample) {
+ return static_cast<s16>(static_cast<u16>(sample) << 8);
+ };
+
StereoBuffer16 ret(sample_count);
if (num_channels == 1) {
for (size_t i = 0; i < sample_count; i++) {
- ret[i].fill(SignExtendS8(data[i]));
+ ret[i].fill(decode_sample(data[i]));
}
} else {
for (size_t i = 0; i < sample_count; i++) {
- ret[i][0] = SignExtendS8(data[i * 2 + 0]);
- ret[i][1] = SignExtendS8(data[i * 2 + 1]);
+ ret[i][0] = decode_sample(data[i * 2 + 0]);
+ ret[i][1] = decode_sample(data[i * 2 + 1]);
}
}