X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=alsa_write.c;h=9d99c8e91af6c4c78e402f9efde4ce00e40cb785;hp=3c7c03b467cb9e40a13e1d348a93600c0fdd51b3;hb=ddbd317a575ed43fae187c9ff18c6d53ece76308;hpb=bae94d3ba972bb91626e5f15e2d5ac44da6b041d diff --git a/alsa_write.c b/alsa_write.c index 3c7c03b4..9d99c8e9 100644 --- a/alsa_write.c +++ b/alsa_write.c @@ -16,6 +16,7 @@ #include #include #include +#include #include "para.h" #include "fd.h" @@ -36,10 +37,10 @@ struct private_alsa_write_data { snd_pcm_t *handle; /** Determined and set by alsa_open(). */ int bytes_per_frame; - /** Don't write anything until this time. */ - struct timeval next_chunk; /** The approximate maximum buffer duration in us. */ unsigned buffer_time; + /* Number of frames that fit into the buffer. */ + unsigned buffer_frames; /** * The samplerate given by command line option or the decoder * of the writer node group. @@ -80,18 +81,19 @@ static int alsa_init(struct private_alsa_write_data *pad, pad->channels) < 0) return -E_CHANNEL_COUNT; if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams, - &pad->samplerate, 0) < 0) + &pad->samplerate, NULL) < 0) return -E_SET_RATE; - err = snd_pcm_hw_params_get_buffer_time_max(hwparams, &pad->buffer_time, 0); + err = snd_pcm_hw_params_get_buffer_time_max(hwparams, + &pad->buffer_time, NULL); if (err < 0 || !pad->buffer_time) 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, 0) < 0) + &pad->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, 0); + snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL); snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size); PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size, period_size); @@ -120,6 +122,8 @@ static int alsa_init(struct private_alsa_write_data *pad, 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"); + pad->buffer_frames = 1000 * pad->buffer_time / pad->samplerate; + PARA_INFO_LOG("max buffered frames: %d\n", pad->buffer_frames); return 1; } @@ -140,7 +144,6 @@ static int alsa_open(struct writer_node *wn) else pad->channels = conf->channels_arg; PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate); - tv_add(now, &(struct timeval){0, 100 * 1000}, &pad->next_chunk); return 1; } @@ -148,20 +151,54 @@ static int alsa_write_pre_select(struct sched *s, struct writer_node *wn) { struct private_alsa_write_data *pad = wn->private_data; struct writer_node_group *wng = wn->wng; - struct timeval diff; + struct timeval tv; + snd_pcm_sframes_t avail, underrun; - if (!*wng->loaded) + if (!pad->handle) return 1; - if (tv_diff(now, &pad->next_chunk, &diff) < 0) { - if (tv_diff(&s->timeout, &diff, NULL) > 0) - s->timeout = diff; - } else { - s->timeout.tv_sec = 0; - s->timeout.tv_usec = 1; - } + if (*wng->loaded - wn->written < pad->bytes_per_frame) + return 1; + /* + * 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; + ms2tv(underrun, &tv); + if (tv_diff(&s->timeout, &tv, NULL) > 0) + s->timeout = tv; return 1; } +static void xrun(snd_pcm_t *handle) +{ + snd_pcm_status_t *status; + int ret; + struct timeval tv, diff; + + snd_pcm_status_alloca(&status); + ret = snd_pcm_status(handle, status); + if (ret < 0) + return; + if (snd_pcm_status_get_state(status) != SND_PCM_STATE_XRUN) + return; + snd_pcm_status_get_trigger_tstamp(status, &tv); + tv_diff(now, &tv, &diff); + PARA_WARNING_LOG("underrun: %lums\n", tv2ms(&diff)); +} + static int alsa_write_post_select(__a_unused struct sched *s, struct writer_node *wn) { @@ -169,7 +206,6 @@ static int alsa_write_post_select(__a_unused struct sched *s, struct writer_node_group *wng = wn->wng; size_t bytes = *wng->loaded - wn->written; unsigned char *data = (unsigned char*)*wng->bufp + wn->written; - struct timeval tv; snd_pcm_sframes_t ret, frames, avail; if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) { @@ -178,8 +214,6 @@ static int alsa_write_post_select(__a_unused struct sched *s, } if (!bytes) /* no data available */ return 0; - if (tv_diff(now, &pad->next_chunk, NULL) < 0) - return 0; if (!pad->handle) { int err = alsa_init(pad, wn->conf); if (err < 0) @@ -190,26 +224,22 @@ static int alsa_write_post_select(__a_unused struct sched *s, return 0; avail = snd_pcm_avail_update(pad->handle); if (avail <= 0) - goto delay; + return 0; frames = PARA_MIN(frames, avail); ret = snd_pcm_writei(pad->handle, data, frames); - if (ret < 0) { - PARA_WARNING_LOG("%s\n", snd_strerror(-ret)); - if (ret == -EPIPE) { - snd_pcm_prepare(pad->handle); - return 0; - } - if (ret == -EAGAIN) - goto delay; - return -E_ALSA_WRITE; + if (ret >= 0) { + wn->written += ret * pad->bytes_per_frame; + return 1; } - wn->written += ret * pad->bytes_per_frame; - return 1; -delay: - /* wait until 50% buffer space is available */ - ms2tv(pad->buffer_time / 2000, &tv); - tv_add(now, &tv, &pad->next_chunk); - return 0; + if (ret == -EPIPE) { + xrun(pad->handle); + snd_pcm_prepare(pad->handle); + return 0; + } + PARA_WARNING_LOG("%s\n", snd_strerror(-ret)); + if (ret == -EAGAIN) + return 0; + return -E_ALSA_WRITE; } static void alsa_close(struct writer_node *wn) @@ -264,4 +294,5 @@ void alsa_write_init(struct writer *w) .short_help = alsa_write_args_info_help, .detailed_help = alsa_write_args_info_detailed_help }; + alsa_cmdline_parser_free(&dummy); }