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libvisual-plugins: Improve ALSA input plugin #169

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Merged
hartwork merged 4 commits into from
Jan 14, 2023
Merged

libvisual-plugins: Improve ALSA input plugin #169

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85bb050
Plugins (alsa): Open device "default" rather than "hw:0,0"
hartwork Jan 6, 2023
b5c4c86
Plugins (alsa): Clarify that snd_pcm_readi is thinking in frames
hartwork Jan 7, 2023
66fe06a
Plugins (alsa): Clarify upload buffer size math
hartwork Jan 7, 2023
85c9e0f
Plugins (alsa): Reduce latency
hartwork Jan 7, 2023
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2 changes: 1 addition & 1 deletion libvisual-plugins/plugins/input/alsa/CMakeLists.txt
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
LV_BUILD_INPUT_PLUGIN(alsa
SOURCES input_alsa.c
LINK_LIBS ALSA::ALSA
LINK_LIBS ALSA::ALSA m
)
18 changes: 10 additions & 8 deletions libvisual-plugins/plugins/input/alsa/input_alsa.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,8 @@
#include "config.h"
#include "gettext.h"

#include <math.h>

#include <libvisual/libvisual.h>

#include <alsa/version.h>
Expand All @@ -50,8 +52,9 @@ static int inp_alsa_init (VisPluginData *plugin);
static void inp_alsa_cleanup (VisPluginData *plugin);
static int inp_alsa_upload (VisPluginData *plugin, VisAudio *audio);

static const char *inp_alsa_var_cdevice = "hw:0,0";
static const char *inp_alsa_var_cdevice = "default";
static const int inp_alsa_var_samplerate = 44100;
static const int inp_alsa_var_frames_target = 256;
static const int inp_alsa_var_channels = 2;

const VisPluginInfo *get_plugin_info (void)
Expand Down Expand Up @@ -154,16 +157,14 @@ int inp_alsa_init (VisPluginData *plugin)
return FALSE;
}

/* Setup a large buffer */

tmp = 1000000;
tmp = (int)ceil((1000.0 * 1000.0 * inp_alsa_var_frames_target) / inp_alsa_var_samplerate); // in micro seconds
if (snd_pcm_hw_params_set_period_time_near(priv->chandle, hwparams, &tmp, &dir) < 0){
visual_log(VISUAL_LOG_ERROR, "Error setting period time");
snd_pcm_hw_params_free(hwparams);
return FALSE;
}

tmp = 1000000*4;
tmp = (int)ceil((1000.0 * 1000.0 * inp_alsa_var_frames_target) / inp_alsa_var_samplerate); // in micro seconds
if (snd_pcm_hw_params_set_buffer_time_near(priv->chandle, hwparams, &tmp, &dir) < 0){
visual_log(VISUAL_LOG_ERROR, "Error setting buffer time");
snd_pcm_hw_params_free(hwparams);
Expand Down Expand Up @@ -206,15 +207,16 @@ int inp_alsa_upload (VisPluginData *plugin, VisAudio *audio)
alsaPrivate *priv = visual_plugin_get_private (plugin);

int16_t data[PCM_BUF_SIZE];
int rcnt;
const snd_pcm_uframes_t frames_wanted = sizeof(data) / sizeof(data[0]) / inp_alsa_var_channels;
snd_pcm_sframes_t rcnt;

do {
rcnt = snd_pcm_readi(priv->chandle, data, PCM_BUF_SIZE / 2);
rcnt = snd_pcm_readi(priv->chandle, data, frames_wanted);

if (rcnt > 0) {
VisBuffer *buffer;

buffer = visual_buffer_new_wrap_data (data, rcnt*2*sizeof(int16_t), FALSE);
buffer = visual_buffer_new_wrap_data (data, rcnt * sizeof(data[0]) * inp_alsa_var_channels, FALSE);

visual_audio_input (audio, buffer, VISUAL_AUDIO_SAMPLE_RATE_44100,
VISUAL_AUDIO_SAMPLE_FORMAT_S16, VISUAL_AUDIO_SAMPLE_CHANNEL_STEREO);
Expand Down