X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=alsa_write.c;h=2dab8fe1543f9205d8d12d7fa9db85be60768df6;hp=5965159ed9e50af87401f4f2968d7155439bb568;hb=b9d2cfbf8415ecacfe57b8cb94d97b662d3a3352;hpb=85bbc6ae5732ffb1269dea6dedbbe81544cebe96 diff --git a/alsa_write.c b/alsa_write.c index 5965159e..2dab8fe1 100644 --- a/alsa_write.c +++ b/alsa_write.c @@ -36,10 +36,6 @@ struct private_alsa_write_data { snd_pcm_t *handle; /** Determined and set by alsa_init(). */ int bytes_per_frame; - /** The approximate maximum buffer duration in us. */ - unsigned buffer_time; - /* Number of frames that fit into the buffer. */ - snd_pcm_uframes_t buffer_frames; /** * The sample rate given by command line option or the decoder * of the writer node group. @@ -52,6 +48,8 @@ struct private_alsa_write_data { */ unsigned channels; struct timeval drain_barrier; + /* File descriptor for select(). */ + int poll_fd; }; static snd_pcm_format_t get_alsa_pcm_format(enum sample_format sf) @@ -74,7 +72,9 @@ static int alsa_init(struct private_alsa_write_data *pad, snd_pcm_hw_params_t *hwparams; snd_pcm_sw_params_t *swparams; snd_pcm_uframes_t start_threshold, stop_threshold; - snd_pcm_uframes_t period_size; + snd_pcm_uframes_t buffer_size, period_size; + snd_output_t *log; + unsigned buffer_time; int err; PARA_INFO_LOG("opening %s\n", conf->device_arg); @@ -100,32 +100,30 @@ static int alsa_init(struct private_alsa_write_data *pad, &pad->sample_rate, NULL) < 0) return -E_SET_RATE; err = snd_pcm_hw_params_get_buffer_time_max(hwparams, - &pad->buffer_time, NULL); - if (err < 0 || !pad->buffer_time) + &buffer_time, NULL); + if (err < 0 || buffer_time == 0) return -E_GET_BUFFER_TIME; - PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time); if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams, - &pad->buffer_time, NULL) < 0) + &buffer_time, NULL) < 0) return -E_SET_BUFFER_TIME; if (snd_pcm_hw_params(pad->handle, hwparams) < 0) return -E_HW_PARAMS; snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL); - snd_pcm_hw_params_get_buffer_size(hwparams, &pad->buffer_frames); - PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad->buffer_frames, - period_size); - if (period_size == pad->buffer_frames) + snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size); + if (period_size == buffer_size) return -E_BAD_PERIOD; + /* software parameter setup */ snd_pcm_sw_params_current(pad->handle, swparams); snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size); - if (pad->buffer_frames < 1) + if (buffer_size < 1) start_threshold = 1; else - start_threshold = PARA_MIN(pad->buffer_frames, + start_threshold = PARA_MIN(buffer_size, (snd_pcm_uframes_t)pad->sample_rate); if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams, start_threshold) < 0) return -E_START_THRESHOLD; - stop_threshold = pad->buffer_frames; + stop_threshold = buffer_size; if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams, stop_threshold) < 0) return -E_STOP_THRESHOLD; @@ -135,19 +133,36 @@ static int alsa_init(struct private_alsa_write_data *pad, * pad->channels / 8; if (pad->bytes_per_frame <= 0) return -E_PHYSICAL_WIDTH; - PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame); if (snd_pcm_nonblock(pad->handle, 1)) PARA_ERROR_LOG("failed to set nonblock mode\n"); + err = snd_output_buffer_open(&log); + if (err == 0) { + char *buf; + PARA_INFO_LOG("dumping alsa configuration\n"); + snd_pcm_dump(pad->handle, log); + snd_output_buffer_string(log, &buf); + for (;;) { + char *p = strchr(buf, '\n'); + if (!p) /* omit last output line, it's empty */ + break; + *p = '\0'; + PARA_INFO_LOG("%s\n", buf); + buf = p + 1; + } + snd_output_close(log); + } return 1; } static void alsa_write_pre_select(struct sched *s, struct task *t) { + struct pollfd pfd; struct writer_node *wn = container_of(t, struct writer_node, task); struct private_alsa_write_data *pad = wn->private_data; - snd_pcm_sframes_t avail, underrun; int ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF); + if (pad) + pad->poll_fd = -1; if (ret == 0) return; if (!pad) { @@ -158,25 +173,14 @@ static void alsa_write_pre_select(struct sched *s, struct task *t) sched_request_barrier_or_min_delay(&pad->drain_barrier, s); return; } - /* - * Data is available to be written to the alsa handle. Compute number - * of milliseconds until next buffer underrun would occur. - * - * snd_pcm_avail_update() updates the current available count of - * samples for writing. It is a light method to obtain current stream - * position, because it does not require the user <-> kernel context - * switch, but the value is less accurate, because ring buffer pointers - * are updated in kernel drivers only when an interrupt occurs. - */ - avail = snd_pcm_avail_update(pad->handle); - if (avail < 0) - avail = 0; - underrun = (pad->buffer_frames - avail) * pad->buffer_time - / pad->buffer_frames / 1000; - if (underrun < 50) - underrun = 50; - underrun -= 50; - sched_request_timeout_ms(underrun, s); + ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1); + if (ret < 0) { + PARA_ERROR_LOG("%s\n", snd_strerror(-ret)); + t->error = -E_ALSA_POLL_FDS; + return; + } + pad->poll_fd = pfd.fd; + para_fd_set(pfd.fd, &s->rfds, &s->max_fileno); } static void alsa_close(struct writer_node *wn) @@ -255,10 +259,23 @@ again: wn->min_iqs = pad->bytes_per_frame; goto again; } + if (pad->poll_fd < 0 || !FD_ISSET(pad->poll_fd, &s->rfds)) + return; frames = bytes / pad->bytes_per_frame; frames = snd_pcm_writei(pad->handle, data, frames); - if (frames == 0 || frames == -EAGAIN) + if (frames == 0 || frames == -EAGAIN) { + /* + * The alsa poll fd was ready for IO but we failed to write to + * the alsa handle. This means another event is pending. We + * don't care about that but we have to dispatch the event in + * order to avoid a busy loop. So we simply read from the poll + * fd. + */ + char buf[100]; + if (read(pad->poll_fd, buf, 100)) + do_nothing; return; + } if (frames > 0) { btr_consume(btrn, frames * pad->bytes_per_frame); goto again;