From 4218fdd77f1c8ab4dab5ced30c3a0db946a6f04c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Volker=20R=C3=BCmelin?= Date: Sun, 8 Mar 2020 20:33:19 +0100 Subject: [PATCH] audio: change mixing engine float range to [-1.f, 1.f] MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently the internal float range of the mixing engine is [-.5f, .5f]. PulseAudio, SDL2 and libasound use a [-1.f, 1.f] range. This means with float samples the audio playback volume is 6dB too low and audio recording signals will be clipped in most cases. To avoid another scaling factor in the conv_natural_float_* and clip_natural_float_* functions with FLOAT_MIXENG defined this patch changes the mixing engine float range to [-1.f, 1.f]. Signed-off-by: Volker Rümelin Message-id: 20200308193321.20668-4-vr_qemu@t-online.de Signed-off-by: Gerd Hoffmann --- audio/mixeng.c | 4 ++-- audio/mixeng_template.h | 17 ++++++++--------- 2 files changed, 10 insertions(+), 11 deletions(-) diff --git a/audio/mixeng.c b/audio/mixeng.c index 725b529be7..739a500449 100644 --- a/audio/mixeng.c +++ b/audio/mixeng.c @@ -271,11 +271,11 @@ f_sample *mixeng_clip[2][2][2][3] = { #define CONV_NATURAL_FLOAT(x) (x) #define CLIP_NATURAL_FLOAT(x) (x) #else -static const float float_scale = UINT_MAX; +static const float float_scale = UINT_MAX / 2.f; #define CONV_NATURAL_FLOAT(x) ((x) * float_scale) #ifdef RECIPROCAL -static const float float_scale_reciprocal = 1.f / UINT_MAX; +static const float float_scale_reciprocal = 2.f / UINT_MAX; #define CLIP_NATURAL_FLOAT(x) ((x) * float_scale_reciprocal) #else #define CLIP_NATURAL_FLOAT(x) ((x) / float_scale) diff --git a/audio/mixeng_template.h b/audio/mixeng_template.h index 77cc89b9e8..fc8e1d4d9e 100644 --- a/audio/mixeng_template.h +++ b/audio/mixeng_template.h @@ -41,32 +41,31 @@ static inline mixeng_real glue (conv_, ET) (IN_T v) #ifdef RECIPROCAL #ifdef SIGNED - return nv * (1.f / (mixeng_real) (IN_MAX - IN_MIN)); + return nv * (2.f / ((mixeng_real)IN_MAX - IN_MIN)); #else - return (nv - HALF) * (1.f / (mixeng_real) IN_MAX); + return (nv - HALF) * (2.f / (mixeng_real)IN_MAX); #endif #else /* !RECIPROCAL */ #ifdef SIGNED - return nv / (mixeng_real) ((mixeng_real) IN_MAX - IN_MIN); + return nv / (((mixeng_real)IN_MAX - IN_MIN) / 2.f); #else - return (nv - HALF) / (mixeng_real) IN_MAX; + return (nv - HALF) / ((mixeng_real)IN_MAX / 2.f); #endif #endif } static inline IN_T glue (clip_, ET) (mixeng_real v) { - if (v >= 0.5) { + if (v >= 1.f) { return IN_MAX; - } - else if (v < -0.5) { + } else if (v < -1.f) { return IN_MIN; } #ifdef SIGNED - return ENDIAN_CONVERT ((IN_T) (v * ((mixeng_real) IN_MAX - IN_MIN))); + return ENDIAN_CONVERT((IN_T)(v * (((mixeng_real)IN_MAX - IN_MIN) / 2.f))); #else - return ENDIAN_CONVERT ((IN_T) ((v * IN_MAX) + HALF)); + return ENDIAN_CONVERT((IN_T)((v * ((mixeng_real)IN_MAX / 2.f)) + HALF)); #endif }