diff options
| author | Oswald Buddenhagen <oswald.buddenhagen@gmx.de> | 2023-05-14 19:03:22 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2023-05-15 22:06:21 +0200 |
| commit | 1298bc978afba0a507cedd0a91e53267ca152804 (patch) | |
| tree | c296aac53cf5a76dd91ed58cfc6fc6bd899a47f7 /include/uapi/sound | |
| parent | ALSA: emu10k1: skip mic capture PCM for cards without AC97 codec (diff) | |
| download | linux-1298bc978afba0a507cedd0a91e53267ca152804.tar.xz linux-1298bc978afba0a507cedd0a91e53267ca152804.zip | |
ALSA: emu10k1: enable bit-exact playback, part 1: DSP attenuation
Fractional multiplication with the maximal value 2^31-1 causes some tiny
distortion. Instead, we want to multiply with the full 2^31. The catch
is of course that this cannot be represented in the DSP's signed 32 bit
registers.
One way to deal with this is to encode 1.0 as a negative number and
special-case it. As a matter of fact, the SbLive! code path already
contained such code, though the controls never actually exercised it.
A more efficient approach is to use negative values, which actually
extend to -2^31. Accordingly, for all the volume adjustments we now use
the MAC1 instruction which negates the X operand.
The range of the controls in highres mode is extended downwards, so -1
is the new zero/mute. At maximal excursion, real zero is not mute any
more, but I don't think anyone will notice this behavior change. ;-)
That also required making the min/max/values in the control structs
signed. This technically changes the user space interface, but it seems
implausible that someone would notice - the numbers were actually
treated as if they were signed anyway (and in the actual mixer iface
they _are_). And without this change, the min value didn't even make
sense in the first place (and no-one noticed, because it was always 0).
Tested-by: Jonathan Dowland <jon@dow.land>
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230514170323.3408834-7-oswald.buddenhagen@gmx.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'include/uapi/sound')
| -rw-r--r-- | include/uapi/sound/emu10k1.h | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/include/uapi/sound/emu10k1.h b/include/uapi/sound/emu10k1.h index c8e131d6da00..4c32a116e7ad 100644 --- a/include/uapi/sound/emu10k1.h +++ b/include/uapi/sound/emu10k1.h @@ -308,6 +308,8 @@ struct snd_emu10k1_fx8010_info { #define EMU10K1_GPR_TRANSLATION_BASS 2 #define EMU10K1_GPR_TRANSLATION_TREBLE 3 #define EMU10K1_GPR_TRANSLATION_ONOFF 4 +#define EMU10K1_GPR_TRANSLATION_NEGATE 5 +#define EMU10K1_GPR_TRANSLATION_NEG_TABLE100 6 enum emu10k1_ctl_elem_iface { EMU10K1_CTL_ELEM_IFACE_MIXER = 2, /* virtual mixer device */ @@ -328,9 +330,9 @@ struct snd_emu10k1_fx8010_control_gpr { unsigned int vcount; /* visible count */ unsigned int count; /* count of GPR (1..16) */ unsigned short gpr[32]; /* GPR number(s) */ - unsigned int value[32]; /* initial values */ - unsigned int min; /* minimum range */ - unsigned int max; /* maximum range */ + int value[32]; /* initial values */ + int min; /* minimum range */ + int max; /* maximum range */ unsigned int translation; /* translation type (EMU10K1_GPR_TRANSLATION*) */ const unsigned int *tlv; }; |