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ALSA: Make device initialization a bit more robust.

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- The buffer size is now set with set_buffer_size_near()
 - The size of the buffer is now independant of periods
 - snd_pcm_sw_params_set_avail_min() is now called with the previous
   power of 2 rather than the next.
 - The start threshold is now called with the previous power of 2
   rather than the next.
This commit is contained in:
David Reid
2016-10-19 18:16:19 +10:00
parent e2c93382f8
commit f9130d74c1
1 changed files with 34 additions and 26 deletions
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mini_al.h
+34 -26
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@@ -633,6 +633,10 @@ static unsigned int mal_next_power_of_2(unsigned int x)
return x;
}
static unsigned int mal_prev_power_of_2(unsigned int x)
{
return mal_next_power_of_2(x) >> 1;
}
///////////////////////////////////////////////////////////////////////////////
@@ -2209,22 +2213,49 @@ static mal_result mal_device_init__alsa(mal_device* pDevice, mal_device_type typ
// Most important properties first.
// Sample Rate
if (snd_pcm_hw_params_set_rate_near((snd_pcm_t*)pDevice->alsa.pPCM, pHWParams, &sampleRate, 0) < 0) {
mal_device_uninit__alsa(pDevice);
return mal_post_error(pDevice, "[ALSA] Sample rate not supported. snd_pcm_hw_params_set_rate_near() failed.", MAL_FORMAT_NOT_SUPPORTED);
}
pDevice->sampleRate = sampleRate;
// Channels.
if (snd_pcm_hw_params_set_channels_near((snd_pcm_t*)pDevice->alsa.pPCM, pHWParams, &channels) < 0) {
mal_device_uninit__alsa(pDevice);
return mal_post_error(pDevice, "[ALSA] Failed to set channel count. snd_pcm_hw_params_set_channels_near() failed.", MAL_FORMAT_NOT_SUPPORTED);
}
pDevice->channels = channels;
// Format.
if (snd_pcm_hw_params_set_format((snd_pcm_t*)pDevice->alsa.pPCM, pHWParams, formatALSA) < 0) {
mal_device_uninit__alsa(pDevice);
return mal_post_error(pDevice, "[ALSA] Format not supported. snd_pcm_hw_params_set_format() failed.", MAL_FORMAT_NOT_SUPPORTED);
}
// Buffer Size
snd_pcm_uframes_t bufferSize = fragmentSizeInFrames * pDevice->fragmentCount;
if (snd_pcm_hw_params_set_buffer_size_near((snd_pcm_t*)pDevice->alsa.pPCM, pHWParams, &bufferSize) < 0) {
mal_device_uninit__alsa(pDevice);
return mal_post_error(pDevice, "[ALSA] Failed to set buffer size for device. snd_pcm_hw_params_set_buffer_size() failed.", MAL_FORMAT_NOT_SUPPORTED);
}
// Periods.
int dir = 1;
if (snd_pcm_hw_params_set_periods_near((snd_pcm_t*)pDevice->alsa.pPCM, pHWParams, &fragmentCount, &dir) < 0) {
mal_device_uninit__alsa(pDevice);
return mal_post_error(pDevice, "[ALSA] Failed to set fragment count. snd_pcm_hw_params_set_periods_near() failed.", MAL_FORMAT_NOT_SUPPORTED);
}
pDevice->fragmentCount = fragmentCount;
pDevice->fragmentSizeInFrames = bufferSize / pDevice->fragmentCount;
// MMAP Mode
//
// Try using interleaved MMAP access. If this fails, fall back to standard readi/writei.
pDevice->alsa.isUsingMMap = MAL_FALSE;
#ifdef MAL_ENABLE_EXPERIMENTAL_ALSA_MMAP
@@ -2241,31 +2272,8 @@ static mal_result mal_device_init__alsa(mal_device* pDevice, mal_device_type typ
}
}
int dir = 1;
if (snd_pcm_hw_params_set_periods_near((snd_pcm_t*)pDevice->alsa.pPCM, pHWParams, &fragmentCount, &dir) < 0) {
mal_device_uninit__alsa(pDevice);
return mal_post_error(pDevice, "[ALSA] Failed to set fragment count. snd_pcm_hw_params_set_periods_near() failed.", MAL_FORMAT_NOT_SUPPORTED);
}
// A few properties may have been adjusted so we need to make sure the device object is aware.
pDevice->channels = channels;
pDevice->sampleRate = sampleRate;
pDevice->fragmentCount = fragmentCount;
// According to the ALSA documentation, the value passed to snd_pcm_sw_params_set_avail_min() must be a power
// of 2 on some hardware. The value passed to this function is the size in frames of a fragment. Thus, to be
// as robust as possible the size of the hardware buffer should be sized based on the size of the next power-
// of-two frame count.
pDevice->fragmentSizeInFrames = mal_next_power_of_2(fragmentSizeInFrames);
if (snd_pcm_hw_params_set_buffer_size((snd_pcm_t*)pDevice->alsa.pPCM, pHWParams, pDevice->fragmentSizeInFrames * pDevice->fragmentCount) < 0) {
mal_device_uninit__alsa(pDevice);
return mal_post_error(pDevice, "[ALSA] Failed to set buffer size for device. snd_pcm_hw_params_set_buffer_size() failed.", MAL_FORMAT_NOT_SUPPORTED);
}
// Apply hardware parameters.
if (snd_pcm_hw_params((snd_pcm_t*)pDevice->alsa.pPCM, pHWParams) < 0) {
mal_device_uninit__alsa(pDevice);
return mal_post_error(pDevice, "[ALSA] Failed to set hardware parameters. snd_pcm_hw_params() failed.", MAL_ALSA_FAILED_TO_SET_SW_PARAMS);
@@ -2281,13 +2289,13 @@ static mal_result mal_device_init__alsa(mal_device* pDevice, mal_device_type typ
return mal_post_error(pDevice, "[ALSA] Failed to initialize software parameters. snd_pcm_sw_params_current() failed.", MAL_ALSA_FAILED_TO_SET_SW_PARAMS);
}
if (snd_pcm_sw_params_set_avail_min((snd_pcm_t*)pDevice->alsa.pPCM, pSWParams, pDevice->fragmentSizeInFrames) != 0) {
if (snd_pcm_sw_params_set_avail_min((snd_pcm_t*)pDevice->alsa.pPCM, pSWParams, mal_prev_power_of_2(pDevice->fragmentSizeInFrames)) != 0) {
mal_device_uninit__alsa(pDevice);
return mal_post_error(pDevice, "[ALSA] Failed to set fragment size. snd_pcm_sw_params_set_avail_min() failed.", MAL_FORMAT_NOT_SUPPORTED);
}
if (type == mal_device_type_playback) {
if (snd_pcm_sw_params_set_start_threshold((snd_pcm_t*)pDevice->alsa.pPCM, pSWParams, pDevice->fragmentSizeInFrames) != 0) {
if (snd_pcm_sw_params_set_start_threshold((snd_pcm_t*)pDevice->alsa.pPCM, pSWParams, mal_prev_power_of_2(pDevice->fragmentSizeInFrames)) != 0) {
mal_device_uninit__alsa(pDevice);
return mal_post_error(pDevice, "[ALSA] Failed to set start threshold for playback device. snd_pcm_sw_params_set_start_threshold() failed.", MAL_ALSA_FAILED_TO_SET_SW_PARAMS);
}