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ao_alsa: use new padding channels support

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Sometimes, ALSA will return channel layouts with padded channels (NA
speakers). Use them instead of failing.

This still includes the old "braindeath" code to retry with a layout
without NA channels. This might be helpful for performance, and also the
padded channel layout string looks confusing.

To be fair, I have not encountered a case yet which would really need
this, and for which the old "braindeath" code did not fix it.

(cherry picked from commit 85fc6b2a05)
This commit is contained in:
wm4 2015-05-06 21:46:11 +02:00 committed by Diogo Franco (Kovensky)
parent 76d2ba6283
commit 52ed30e9b8
1 changed files with 26 additions and 21 deletions
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47
audio/out/ao_alsa.c
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@ -252,6 +252,7 @@ static const int alsa_to_mp_channels[][2] = {
{SND_CHMAP_TRR, MP_SP(TBR)},
{SND_CHMAP_TRC, MP_SP(TBC)},
{SND_CHMAP_MONO, MP_SP(FC)},
{SND_CHMAP_NA, MP_SPEAKER_ID_NA0},
{SND_CHMAP_LAST, MP_SPEAKER_ID_COUNT}
};
@ -282,9 +283,14 @@ static int mp_chmap_from_alsa(struct mp_chmap *dst, snd_pcm_chmap_t *src)
if (src->channels > MP_NUM_CHANNELS)
return -1;
int next_na = MP_SPEAKER_ID_NA0;
dst->num = src->channels;
for (int c = 0; c < dst->num; c++)
for (int c = 0; c < dst->num; c++) {
dst->speaker[c] = find_mp_channel(src->pos[c]);
if (dst->speaker[c] == MP_SPEAKER_ID_NA0)
dst->speaker[c] = next_na++;
}
return 0;
}
@ -412,7 +418,7 @@ alsa_error: ;
#define INIT_OK 0
#define INIT_ERROR -1
#define INIT_BRAINDEATH -2
static int init_device(struct ao *ao)
static int init_device(struct ao *ao, bool second_try)
{
struct priv *p = ao->priv;
int err;
@ -582,24 +588,14 @@ static int init_device(struct ao *ao)
} else if (AF_FORMAT_IS_IEC61937(ao->format)) {
MP_VERBOSE(ao, "using spdif passthrough; ignoring the channel map.\n");
} else if (mp_chmap_is_valid(&chmap)) {
if (mp_chmap_equals(&chmap, &ao->channels)) {
MP_VERBOSE(ao, "which is what we requested.\n");
} else if (chmap.num == ao->channels.num) {
MP_VERBOSE(ao, "using the ALSA channel map.\n");
ao->channels = chmap;
} else {
MP_WARN(ao, "ALSA channel map conflicts with channel count!\n");
}
} else {
// Is it one that contains NA channels?
struct mp_chmap chmap2 = {0};
for (int c = 0; c < alsa_chmap->channels; c++) {
int alsa_ch = alsa_chmap->pos[c];
if (alsa_ch != SND_CHMAP_NA)
chmap2.speaker[chmap2.num++] = find_mp_channel(alsa_ch);
}
struct mp_chmap without_na = chmap;
mp_chmap_remove_na(&without_na);
if (mp_chmap_is_valid(&chmap2)) {
if (mp_chmap_is_valid(&without_na) &&
!mp_chmap_equals(&without_na, &chmap) &&
!second_try)
{
// Sometimes, ALSA will advertise certain chmaps, but it's not
// possible to set them. This can happen with dmix: as of
// alsa 1.0.28, dmix can do stereo only, but advertises the
@ -616,10 +612,19 @@ static int init_device(struct ao *ao)
err = snd_pcm_close(p->alsa);
p->alsa = NULL;
CHECK_ALSA_ERROR("pcm close error");
ao->channels = chmap2;
ao->channels = without_na;
return INIT_BRAINDEATH;
}
if (mp_chmap_equals(&chmap, &ao->channels)) {
MP_VERBOSE(ao, "which is what we requested.\n");
} else if (chmap.num == ao->channels.num) {
MP_VERBOSE(ao, "using the ALSA channel map.\n");
ao->channels = chmap;
} else {
MP_WARN(ao, "ALSA channel map conflicts with channel count!\n");
}
} else {
MP_WARN(ao, "Got unknown channel map from ALSA.\n");
}
@ -690,9 +695,9 @@ static int init(struct ao *ao)
MP_VERBOSE(ao, "using ALSA version: %s\n", snd_asoundlib_version());
int r = init_device(ao);
int r = init_device(ao, false);
if (r == INIT_BRAINDEATH)
r = init_device(ao); // retry with normalized channel layout
r = init_device(ao, true); // retry with normalized channel layout
return r == INIT_OK ? 0 : -1;
}