alsa: Set period time.

[paraslash.git] / alsa_write.c

diff --git a/alsa_write.c b/alsa_write.c
index a3912c1165e6054b0be0bd622b17175fdad4fd8a..e75fa23067380244cd451eedc1c523fae3fb004f 100644 (file)
--- a/alsa_write.c
+++ b/alsa_write.c
@@ -34,16 +34,21 @@ struct private_alsa_write_data {
        snd_pcm_t *handle;
        /** Determined and set by alsa_init(). */
        int bytes_per_frame;
-       /**
-        * The sample rate given by command line option or the decoder
-        * of the writer node group.
+       /*
+        * If the sample rate is not given at the command line and no wav
+        * header was detected, the btr exec mechanism is employed to query the
+        * ancestor buffer tree nodes for this information. In a typical setup
+        * the decoder passes the sample rate back to the alsa writer.
+        *
+        *  \sa \ref btr_exec_up().
         */
        unsigned sample_rate;
-       snd_pcm_format_t sample_format;
-       /**
-        * The number of channels, given by command line option or the
-        * decoder of the writer node group.
+       /*
+        * The sample format (8/16 bit, signed/unsigned, little/big endian) is
+        * determined in the same way as the \a sample_rate.
         */
+       snd_pcm_format_t sample_format;
+       /* The number of channels, again determined like \a sample_rate. */
        unsigned channels;
        struct timeval drain_barrier;
        /* File descriptor for select(). */
@@ -75,6 +80,7 @@ static int alsa_init(struct private_alsa_write_data *pad,
        unsigned buffer_time;
        int ret;
        const char *msg;
+       unsigned period_time;
 
        PARA_INFO_LOG("opening %s\n", conf->device_arg);
        msg = "unable to open pcm";
@@ -119,6 +125,13 @@ static int alsa_init(struct private_alsa_write_data *pad,
                &buffer_time, NULL);
        if (ret < 0)
                goto fail;
+       period_time = buffer_time / 4;
+       msg = "could not set period time";
+       ret = snd_pcm_hw_params_set_period_time_near(pad->handle, hwparams,
+               &period_time, 0);
+       if (ret < 0)
+               goto fail;
+
        msg = "unable to install hw params";
        ret = snd_pcm_hw_params(pad->handle, hwparams);
        if (ret < 0)
@@ -166,15 +179,16 @@ static int alsa_init(struct private_alsa_write_data *pad,
        if (ret == 0) {
                char *buf, *p;
                size_t sz;
-               PARA_INFO_LOG("dumping alsa configuration\n");
+               PARA_DEBUG_LOG("dumping alsa configuration\n");
                snd_pcm_dump(pad->handle, output_log);
+               snd_pcm_hw_params_dump(hwparams, output_log);
                sz = snd_output_buffer_string(output_log, &buf);
                for (p = buf; p < buf + sz;) {
                        char *q = memchr(p, '\n', buf + sz - p);
                        if (!q)
                                break;
                        *q = '\0';
-                       PARA_INFO_LOG("%s\n", p);
+                       PARA_DEBUG_LOG("%s\n", p);
                        p = q + 1;
                }
                snd_output_close(output_log);
@@ -211,7 +225,6 @@ static void alsa_write_pre_select(struct sched *s, struct task *t)
        if (ret < 0) {
                PARA_ERROR_LOG("could not get alsa poll fd: %s\n",
                        snd_strerror(-ret));
-               t->error = -E_ALSA;
                return;
        }
        pad->poll_fd = pfd.fd;