Hello, This is a bugfix for SBC decoder. -- Best regards, Siarhei Siamashka
From 3f9180b9b32c17b6f6594ac7e7b03fa0d665c7f8 Mon Sep 17 00:00:00 2001 From: Siarhei Siamashka <siarhei.siamashka@xxxxxxxxx> Date: Fri, 17 Apr 2009 18:27:38 +0300 Subject: [PATCH] sbc: added saturated clipping of decoder output to 16-bit This prevents overflows and audible artefacts for the audio files which originally had loudness maximized. Music from audio CD disks is an example of such files, see http://en.wikipedia.org/wiki/Loudness_war --- sbc/sbc.c | 20 +++++++++++++++----- 1 files changed, 15 insertions(+), 5 deletions(-) diff --git a/sbc/sbc.c b/sbc/sbc.c index a6b6563..14e5869 100644 --- a/sbc/sbc.c +++ b/sbc/sbc.c @@ -534,6 +534,16 @@ static void sbc_decoder_init(struct sbc_decoder_state *state, state->offset[ch][i] = (10 * i + 10); } +static SBC_ALWAYS_INLINE int16_t sbc_clip16(int32_t s) +{ + if (s > 0x7FFF) + return 0x7FFF; + else if (s < -0x8000) + return -0x8000; + else + return s; +} + static inline void sbc_synthesize_four(struct sbc_decoder_state *state, struct sbc_frame *frame, int ch, int blk) { @@ -562,7 +572,7 @@ static inline void sbc_synthesize_four(struct sbc_decoder_state *state, k = (i + 4) & 0xf; /* Store in output, Q0 */ - frame->pcm_sample[ch][blk * 4 + i] = SCALE4_STAGED1( + frame->pcm_sample[ch][blk * 4 + i] = sbc_clip16(SCALE4_STAGED1( MULA(v[offset[i] + 0], sbc_proto_4_40m0[idx + 0], MULA(v[offset[k] + 1], sbc_proto_4_40m1[idx + 0], MULA(v[offset[i] + 2], sbc_proto_4_40m0[idx + 1], @@ -572,7 +582,7 @@ static inline void sbc_synthesize_four(struct sbc_decoder_state *state, MULA(v[offset[i] + 6], sbc_proto_4_40m0[idx + 3], MULA(v[offset[k] + 7], sbc_proto_4_40m1[idx + 3], MULA(v[offset[i] + 8], sbc_proto_4_40m0[idx + 4], - MUL( v[offset[k] + 9], sbc_proto_4_40m1[idx + 4]))))))))))); + MUL( v[offset[k] + 9], sbc_proto_4_40m1[idx + 4])))))))))))); } } @@ -607,8 +617,8 @@ static inline void sbc_synthesize_eight(struct sbc_decoder_state *state, for (idx = 0, i = 0; i < 8; i++, idx += 5) { k = (i + 8) & 0xf; - /* Store in output */ - frame->pcm_sample[ch][blk * 8 + i] = SCALE8_STAGED1( // Q0 + /* Store in output, Q0 */ + frame->pcm_sample[ch][blk * 8 + i] = sbc_clip16(SCALE8_STAGED1( MULA(state->V[ch][offset[i] + 0], sbc_proto_8_80m0[idx + 0], MULA(state->V[ch][offset[k] + 1], sbc_proto_8_80m1[idx + 0], MULA(state->V[ch][offset[i] + 2], sbc_proto_8_80m0[idx + 1], @@ -618,7 +628,7 @@ static inline void sbc_synthesize_eight(struct sbc_decoder_state *state, MULA(state->V[ch][offset[i] + 6], sbc_proto_8_80m0[idx + 3], MULA(state->V[ch][offset[k] + 7], sbc_proto_8_80m1[idx + 3], MULA(state->V[ch][offset[i] + 8], sbc_proto_8_80m0[idx + 4], - MUL( state->V[ch][offset[k] + 9], sbc_proto_8_80m1[idx + 4]))))))))))); + MUL( state->V[ch][offset[k] + 9], sbc_proto_8_80m1[idx + 4])))))))))))); } } -- 1.5.6.5
