Hi Pierre,
pl bossart ha scritto:
> You haven't specified the buffer/period size in the hw params. See
> alsa-lib/test/pcm.c
> - Pierre
They fail when opening default device so I had to remove them, work fine when opening
plughw:0,0 though.
> On Mon, Jan 4, 2010 at 11:39 AM, Riccardo Magliocchetti
> <riccardo.magliocchetti@xxxxxxxxx> wrote:
>> [the same message is waiting in moderator queue, sorry if you receive it two times]
>>
>> Hello,
>>
>> i'm trying to capture audio data from the microphone, but i'm not able to
>> read any frames.
>> The frames are always 0 and delay is fixed to 2730. I've tried calling
>> snd_pcm_avail_delay, snd_pcm_avail_update but does not make a difference.
>> The soundcard is driven by snd_hda_intel. The code is more or less the
>> same as Paul Davis' tutorial on using the alsa api.
>>
>> This is the code for init and the loop that tries to read the data:
>>
>> #define MIC_BUFSIZE 4096
>>
>> static gpointer snd_pcm_read(gpointer data)
>> {
>> int error;
>> snd_pcm_sframes_t frames = MIC_BUFSIZE;
>>
>> while (TRUE) {
>>
>> if ((error = snd_pcm_wait (pcm_handle, 1000)) < 0) {
>> g_printerr("Failed to poll: %s\n", snd_strerror(error));
>> continue;
>> }
>>
>> if ((error = snd_pcm_avail(pcm_handle)) < 0) {
>> if (error == -EPIPE) {
>> g_printerr("xrun! %s\n", snd_strerror(error));
>> continue;
>> //return GINT_TO_POINTER(FALSE);
>> } else {
>> g_printerr("alsa_pcm_avail_update error %s\n", snd_strerror(error));
>> continue;
>> //return GINT_TO_POINTER(FALSE);
>> }
>> }
>>
>> frames = error;
>> if (frames == 0)
>> continue;
>>
>> frames = frames > MIC_BUFSIZE ? MIC_BUFSIZE : frames;
>> g_printerr ("frames: %ld\n", frames);
>> g_static_mutex_lock(&mutex);
>> error = snd_pcm_readi(pcm_handle, Mic_Buffer[Mic_WriteBuf], frames);
>> g_static_mutex_unlock(&mutex);
>> if (error < 0)
>> error = snd_pcm_recover(pcm_handle, error, 0);
>> if (error < 0) {
>> LOG("snd_pcm_readi FAIL!: %s\n", snd_strerror(error));
>> }
>> }
>>
>> return GINT_TO_POINTER(TRUE);
>> }
>>
>> BOOL Mic_Init()
>> {
>> snd_pcm_hw_params_t *hwparams;
>> snd_pcm_sw_params_t *swparams;
>> int err;
>>
>> if (Mic_Inited)
>> return TRUE;
>>
>> // Open the default sound card in capture
>> if ((err = snd_pcm_open(&pcm_handle, "default", SND_PCM_STREAM_CAPTURE,
>> /*SND_PCM_NONBLOCK*/ 0)) < 0) {
>> g_printerr("Failed to open device: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> // Allocate the snd_pcm_hw_params_t structure and fill it.
>> snd_pcm_hw_params_alloca(&hwparams);
>> if ((err = snd_pcm_hw_params_any(pcm_handle, hwparams)) < 0) {
>> g_printerr("Failed to setup hw parameters: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> //Set the access
>> if ((err = snd_pcm_hw_params_set_access(pcm_handle, hwparams,
>> SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
>> g_printerr("Failed to set access: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> //dir 0 == exacte (Rate = 16K exacte)
>> if ((err = snd_pcm_hw_params_set_rate(pcm_handle, hwparams, 16000, 0)) < 0) {
>> g_printerr("Failed to set rate: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> /* Set sample format */
>> if ((err = snd_pcm_hw_params_set_format(pcm_handle, hwparams, SND_PCM_FORMAT_S8)) < 0) {
>> g_printerr("Failed to set format: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> // Set one channel (mono)
>> if ((err = snd_pcm_hw_params_set_channels(pcm_handle, hwparams, 1)) < 0) {
>> g_printerr("Failed to set channels: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> //Set the params
>> if ((err = snd_pcm_hw_params(pcm_handle, hwparams)) < 0) {
>> g_printerr("Failed to set hw parameters: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> snd_pcm_sw_params_alloca(&swparams);
>> if ((err = snd_pcm_sw_params_current (pcm_handle, swparams)) < 0) {
>> g_printerr("Failed to set current sw parameters: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> if ((err = snd_pcm_sw_params_set_avail_min (pcm_handle, swparams, MIC_BUFSIZE)) < 0) {
>> g_printerr("Failed to set minimum available count: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> if ((err = snd_pcm_sw_params_set_start_threshold (pcm_handle, swparams, 0U)) < 0) {
>> g_printerr("Failed to set start mode: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> if ((err = snd_pcm_sw_params (pcm_handle, swparams)) < 0) {
>> g_printerr("Failed to set sw parameters: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> if ((err = snd_pcm_prepare (pcm_handle)) < 0) {
>> g_printerr("Failed to prepare audio interface to use: %s\n", snd_strerror(err));
>> return FALSE;
>> }
>>
>> Mic_Inited = TRUE;
>> Mic_Reset();
>>
>> mic_reader = g_thread_create(snd_pcm_read, NULL, TRUE, NULL);
>>
>> return TRUE;
>> }
>>
>>
>> thanks,
>> Riccardo
>>
>> _______________________________________________
>> Alsa-devel mailing list
>> Alsa-devel@xxxxxxxxxxxxxxxx
>> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>>
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