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ALSA: Fix an error with channel mapping.

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This commit is contained in:
David Reid
2017-11-11 09:03:42 +10:00
parent 5aadfef82b
commit 77751bd077
1 changed files with 33 additions and 3 deletions
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mini_al.h
+33 -3
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@@ -6018,9 +6018,39 @@ static mal_result mal_device_init__alsa(mal_context* pContext, mal_device_type t
// instead just do it ourselves.
snd_pcm_chmap_t* pChmap = ((mal_snd_pcm_get_chmap_proc)pContext->alsa.snd_pcm_get_chmap)((snd_pcm_t*)pDevice->alsa.pPCM);
if (pChmap != NULL) {
mal_assert(pChmap->channels == pDevice->internalChannels);
for (mal_uint32 iChannel = 0; iChannel < pDevice->internalChannels; ++iChannel) {
pDevice->internalChannelMap[iChannel] = mal_convert_alsa_channel_position_to_mal_channel(pChmap->pos[iChannel]);
// There are cases where the returned channel map can have a different channel count than was returned by snd_pcm_hw_params_set_channels_near().
if (pChmap->channels >= pDevice->internalChannels) {
// Drop excess channels.
for (mal_uint32 iChannel = 0; iChannel < pDevice->internalChannels; ++iChannel) {
pDevice->internalChannelMap[iChannel] = mal_convert_alsa_channel_position_to_mal_channel(pChmap->pos[iChannel]);
}
} else {
// Excess channels use defaults. Do an initial fill with defaults, overwrite the first pChmap->channels, validate to ensure there are no duplicate
// channels. If validation fails, fall back to defaults.
// Fill with defaults.
mal_get_default_channel_mapping(pDevice->pContext->backend, pDevice->internalChannels, pDevice->internalChannelMap);
// Overwrite first pChmap->channels channels.
for (mal_uint32 iChannel = 0; iChannel < pChmap->channels; ++iChannel) {
pDevice->internalChannelMap[iChannel] = mal_convert_alsa_channel_position_to_mal_channel(pChmap->pos[iChannel]);
}
// Validate.
mal_bool32 isValid = MAL_TRUE;
for (mal_uint32 i = 0; i < pDevice->internalChannels && isValid; ++i) {
for (mal_uint32 j = i+1; j < pDevice->internalChannels; ++j) {
if (pDevice->internalChannelMap[i] == pDevice->internalChannelMap[j]) {
isValid = MAL_FALSE;
break;
}
}
}
// If our channel map is invalid, fall back to defaults.
if (!isValid) {
mal_get_default_channel_mapping(pDevice->pContext->backend, pDevice->internalChannels, pDevice->internalChannelMap);
}
}
free(pChmap);