rounds alsa HW mixer volume towards ±∞ depending on sgn(∆ vol)

This alleviates a problem in which 'volume +1' cannot be undo by
'volume -1' when using alsa hw mixer.

Closes #104
This commit is contained in:
Stefano Miccoli 2017-12-12 23:42:42 +01:00 committed by Max Kellermann
parent f1ef9f9d31
commit 967af60327
2 changed files with 5 additions and 1 deletions

2
NEWS
View File

@ -1,6 +1,8 @@
ver 0.20.13 (not yet released)
* output
- osx: set up ring buffer to hold at least 100ms
* mixer
- alsa: fix rounding errors
* database
- simple: don't purge mount points on update/rescan
- simple: fix "mount" bug caused by bad compiler optimization

View File

@ -292,7 +292,9 @@ AlsaMixer::SetVolume(unsigned volume)
{
assert(handle != nullptr);
int err = set_normalized_playback_volume(elem, 0.01*volume, 1);
double cur = get_normalized_playback_volume(elem, SND_MIXER_SCHN_FRONT_LEFT);
int delta = volume - lrint(100.*cur);
int err = set_normalized_playback_volume(elem, cur + 0.01*delta, delta);
if (err < 0)
throw FormatRuntimeError("failed to set ALSA volume: %s",
snd_strerror(err));