From: Andre Noll Date: Sat, 3 May 2014 17:56:01 +0000 (+0200) Subject: Merge branch 't/alsa_improvements' X-Git-Tag: v0.5.3~22 X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=bfdd36f2879b8dee1f6d3330bc49fbb5644d3caf;hp=d1c8428d048631addb89bbb6bd17ade6398dbb89 Merge branch 't/alsa_improvements' Was cooking for almost two months. * t/alsa_improvements: alsa: Remove pointless initialization. alsa_mix: Allow non-positive mixer values. alsa: New writer option: --buffer-time. alsa: Work around poll fd problems. alsa: Set period time. alsa: Also dump hardware params. alsa: Improve help text of --device. alsa: Improve documentation of struct private_alsa_write_data. alsa: Don't set t->error in ->pre_select(). --- diff --git a/NEWS b/NEWS index 508288ec..7cf5dca2 100644 --- a/NEWS +++ b/NEWS @@ -1,6 +1,12 @@ NEWS ==== +------------------------------------------------- +0.5.3 (to be released) "symbolic synchronization" +------------------------------------------------- + + - Various alsa-related fixes, mostly for the raspberry pi. + ---------------------------------------- 0.5.2 (2014-04-11) "orthogonal interior" ---------------------------------------- diff --git a/alsa_mix.c b/alsa_mix.c index be38e887..c860efc8 100644 --- a/alsa_mix.c +++ b/alsa_mix.c @@ -150,7 +150,7 @@ static int alsa_mix_set_channel(struct mixer_handle *h, mixer_channel, h->card, snd_strerror(ret)); return -E_ALSA_MIX_RANGE; } - if (h->pmin < 0 || h->pmax < 0 || h->pmin >= h->pmax) { + if (h->pmin >= h->pmax) { PARA_NOTICE_LOG("alsa reported %s range %ld-%ld (%s)\n", mixer_channel, h->pmin, h->pmax, h->card); return -E_ALSA_MIX_RANGE; diff --git a/alsa_write.c b/alsa_write.c index ad59a829..3759306e 100644 --- a/alsa_write.c +++ b/alsa_write.c @@ -34,17 +34,24 @@ 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; + /* time until buffer underrun occurs, in milliseconds */ + unsigned buffer_time; struct timeval drain_barrier; /* File descriptor for select(). */ int poll_fd; @@ -72,9 +79,9 @@ static int alsa_init(struct private_alsa_write_data *pad, snd_pcm_uframes_t start_threshold, stop_threshold; snd_pcm_uframes_t buffer_size, period_size; snd_output_t *output_log; - 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"; @@ -107,18 +114,21 @@ static int alsa_init(struct private_alsa_write_data *pad, &pad->sample_rate, NULL); if (ret < 0) goto fail; - msg = "unable to get buffer time"; - ret = snd_pcm_hw_params_get_buffer_time_max(hwparams, &buffer_time, - NULL); - if (ret < 0 || buffer_time == 0) - goto fail; - /* buffer at most 500 milliseconds */ - buffer_time = PARA_MIN(buffer_time, 500U * 1000U); + /* alsa wants microseconds */ + pad->buffer_time = conf->buffer_time_arg * 1000; msg = "could not set buffer time"; ret = snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams, - &buffer_time, NULL); + &pad->buffer_time, NULL); + if (ret < 0) + goto fail; + pad->buffer_time /= 1000; /* we prefer milliseconds */ + period_time = pad->buffer_time * 250; /* 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 +176,16 @@ 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); @@ -207,11 +218,12 @@ static void alsa_write_pre_select(struct sched *s, struct task *t) sched_request_barrier_or_min_delay(&pad->drain_barrier, s); return; } + /* wait at most 50% of the buffer time */ + sched_request_timeout_ms(pad->buffer_time / 2, s); ret = snd_pcm_poll_descriptors(pad->handle, &pfd, 1); 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; @@ -296,21 +308,13 @@ again: wn->min_iqs = pad->bytes_per_frame; goto again; } - if (pad->poll_fd < 0 || !FD_ISSET(pad->poll_fd, &s->rfds)) - return 0; frames = bytes / pad->bytes_per_frame; frames = snd_pcm_writei(pad->handle, data, frames); 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; + if (pad->poll_fd >= 0 && FD_ISSET(pad->poll_fd, &s->rfds)) + if (read(pad->poll_fd, buf, 100)) + do_nothing; return 0; } if (frames > 0) { diff --git a/m4/gengetopt/alsa_write.m4 b/m4/gengetopt/alsa_write.m4 index be56c984..b2c56218 100644 --- a/m4/gengetopt/alsa_write.m4 +++ b/m4/gengetopt/alsa_write.m4 @@ -8,11 +8,29 @@ include(header.m4) option "device" d #~~~~~~~~~~~~~~~~ "set PCM device" -string typestr="device" -default="default" +string typestr = "device" +default = "default" optional -details=" - On systems with dmix, a better choice than the default - value might be to use \"plug:swmix\". +details = " + Check for the presence of a /proc/asound/ directory to see if + ALSA is present in your kernel. The file /proc/asound/devices + contains all devices ALSA knows about. " + +option "buffer-time" B +#~~~~~~~~~~~~~~~~~~~~~ +"duration of the ALSA buffer" +int typestr = "milliseconds" +default = "170" +optional +details = " + This is only a hint as ALSA might pick a slightly different + time, depending on the sound hardware. The chosen value is + shown in debug output as BUFFER_TIME. + + If synchronization between multiple clients is desired, + the same buffer time should be configured for all clients. +" + +