X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=alsa_write.c;h=53c973844f6708604a5a58dbadf48a7abbe4329c;hp=df39716fbdd36e1a608c6c197cc3a8d3b36e8a49;hb=4d5a9b90c3e9cbdff019776d05792beb57fbfa31;hpb=813bec7dd99c3f5f43f046af0b1c87d70010dd19 diff --git a/alsa_write.c b/alsa_write.c index df39716f..53c97384 100644 --- a/alsa_write.c +++ b/alsa_write.c @@ -35,10 +35,10 @@ 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. @@ -79,18 +79,19 @@ 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); @@ -119,6 +120,8 @@ 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; } @@ -139,7 +142,6 @@ 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; } @@ -147,17 +149,34 @@ 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; } @@ -166,19 +185,16 @@ static int alsa_write_post_select(__a_unused struct sched *s, { struct private_alsa_write_data *pad = wn->private_data; struct writer_node_group *wng = wn->wng; - size_t frames, bytes = *wng->loaded - wn->written; - unsigned char *data = (unsigned char*)wng->buf + wn->written; - struct timeval tv; - snd_pcm_sframes_t ret; + size_t bytes = *wng->loaded - wn->written; + unsigned char *data = (unsigned char*)*wng->bufp + wn->written; + snd_pcm_sframes_t ret, frames, avail; if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) { wn->written = *wng->loaded; return *wng->input_error; } if (!bytes) /* no data available */ - goto out; - if (tv_diff(now, &pad->next_chunk, NULL) < 0) - goto out; + return 0; if (!pad->handle) { int err = alsa_init(pad, wn->conf); if (err < 0) @@ -186,30 +202,24 @@ static int alsa_write_post_select(__a_unused struct sched *s, } frames = bytes / pad->bytes_per_frame; if (!frames) /* less than a single frame available */ - goto out; + return 0; + avail = snd_pcm_avail_update(pad->handle); + if (avail <= 0) + return 0; + frames = PARA_MIN(frames, avail); ret = snd_pcm_writei(pad->handle, data, frames); - if (ret == -EPIPE) { - PARA_WARNING_LOG("EPIPE\n"); - snd_pcm_prepare(pad->handle); + if (ret >= 0) { + wn->written += ret * pad->bytes_per_frame; return 1; } - if (ret < 0 && ret != -EAGAIN) { - PARA_WARNING_LOG("alsa error (%zu frames, ret = %d\n", - frames, (int)ret); - return -E_ALSA_WRITE; + PARA_WARNING_LOG("%s\n", snd_strerror(-ret)); + if (ret == -EPIPE) { + snd_pcm_prepare(pad->handle); + return 0; } if (ret == -EAGAIN) - PARA_DEBUG_LOG("EAGAIN\n"); - else - wn->written += ret * pad->bytes_per_frame; - if (ret == frames) /* we wrote everything, try again immediately */ - pad->next_chunk = *now; - else { /* wait until 50% buffer space is available */ - ms2tv(pad->buffer_time / 2000, &tv); - tv_add(now, &tv, &pad->next_chunk); - } -out: - return 1; + return 0; + return -E_ALSA_WRITE; } static void alsa_close(struct writer_node *wn) @@ -264,4 +274,5 @@ 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); }