diff options
Diffstat (limited to 'media/libcubeb/src/cubeb_alsa.c')
| -rw-r--r-- | media/libcubeb/src/cubeb_alsa.c | 1149 |
1 files changed, 1149 insertions, 0 deletions
diff --git a/media/libcubeb/src/cubeb_alsa.c b/media/libcubeb/src/cubeb_alsa.c new file mode 100644 index 000000000..1ea0961d0 --- /dev/null +++ b/media/libcubeb/src/cubeb_alsa.c @@ -0,0 +1,1149 @@ +/* + * Copyright © 2011 Mozilla Foundation + * + * This program is made available under an ISC-style license. See the + * accompanying file LICENSE for details. + */ +#undef NDEBUG +#define _DEFAULT_SOURCE +#define _BSD_SOURCE +#define _XOPEN_SOURCE 500 +#include <pthread.h> +#include <sys/time.h> +#include <assert.h> +#include <limits.h> +#include <poll.h> +#include <unistd.h> +#include <alsa/asoundlib.h> +#include "cubeb/cubeb.h" +#include "cubeb-internal.h" + +#define CUBEB_STREAM_MAX 16 +#define CUBEB_WATCHDOG_MS 10000 + +#define CUBEB_ALSA_PCM_NAME "default" + +#define ALSA_PA_PLUGIN "ALSA <-> PulseAudio PCM I/O Plugin" + +/* ALSA is not thread-safe. snd_pcm_t instances are individually protected + by the owning cubeb_stream's mutex. snd_pcm_t creation and destruction + is not thread-safe until ALSA 1.0.24 (see alsa-lib.git commit 91c9c8f1), + so those calls must be wrapped in the following mutex. */ +static pthread_mutex_t cubeb_alsa_mutex = PTHREAD_MUTEX_INITIALIZER; +static int cubeb_alsa_error_handler_set = 0; + +static struct cubeb_ops const alsa_ops; + +struct cubeb { + struct cubeb_ops const * ops; + + pthread_t thread; + + /* Mutex for streams array, must not be held while blocked in poll(2). */ + pthread_mutex_t mutex; + + /* Sparse array of streams managed by this context. */ + cubeb_stream * streams[CUBEB_STREAM_MAX]; + + /* fds and nfds are only updated by alsa_run when rebuild is set. */ + struct pollfd * fds; + nfds_t nfds; + int rebuild; + + int shutdown; + + /* Control pipe for forcing poll to wake and rebuild fds or recalculate the timeout. */ + int control_fd_read; + int control_fd_write; + + /* Track number of active streams. This is limited to CUBEB_STREAM_MAX + due to resource contraints. */ + unsigned int active_streams; + + /* Local configuration with handle_underrun workaround set for PulseAudio + ALSA plugin. Will be NULL if the PA ALSA plugin is not in use or the + workaround is not required. */ + snd_config_t * local_config; + int is_pa; +}; + +enum stream_state { + INACTIVE, + RUNNING, + DRAINING, + PROCESSING, + ERROR +}; + +struct cubeb_stream { + cubeb * context; + pthread_mutex_t mutex; + snd_pcm_t * pcm; + cubeb_data_callback data_callback; + cubeb_state_callback state_callback; + void * user_ptr; + snd_pcm_uframes_t write_position; + snd_pcm_uframes_t last_position; + snd_pcm_uframes_t buffer_size; + cubeb_stream_params params; + + /* Every member after this comment is protected by the owning context's + mutex rather than the stream's mutex, or is only used on the context's + run thread. */ + pthread_cond_t cond; /* Signaled when the stream's state is changed. */ + + enum stream_state state; + + struct pollfd * saved_fds; /* A copy of the pollfds passed in at init time. */ + struct pollfd * fds; /* Pointer to this waitable's pollfds within struct cubeb's fds. */ + nfds_t nfds; + + struct timeval drain_timeout; + + /* XXX: Horrible hack -- if an active stream has been idle for + CUBEB_WATCHDOG_MS it will be disabled and the error callback will be + called. This works around a bug seen with older versions of ALSA and + PulseAudio where streams would stop requesting new data despite still + being logically active and playing. */ + struct timeval last_activity; + float volume; +}; + +static int +any_revents(struct pollfd * fds, nfds_t nfds) +{ + nfds_t i; + + for (i = 0; i < nfds; ++i) { + if (fds[i].revents) { + return 1; + } + } + + return 0; +} + +static int +cmp_timeval(struct timeval * a, struct timeval * b) +{ + if (a->tv_sec == b->tv_sec) { + if (a->tv_usec == b->tv_usec) { + return 0; + } + return a->tv_usec > b->tv_usec ? 1 : -1; + } + return a->tv_sec > b->tv_sec ? 1 : -1; +} + +static int +timeval_to_relative_ms(struct timeval * tv) +{ + struct timeval now; + struct timeval dt; + long long t; + int r; + + gettimeofday(&now, NULL); + r = cmp_timeval(tv, &now); + if (r >= 0) { + timersub(tv, &now, &dt); + } else { + timersub(&now, tv, &dt); + } + t = dt.tv_sec; + t *= 1000; + t += (dt.tv_usec + 500) / 1000; + + if (t > INT_MAX) { + t = INT_MAX; + } else if (t < INT_MIN) { + t = INT_MIN; + } + + return r >= 0 ? t : -t; +} + +static int +ms_until(struct timeval * tv) +{ + return timeval_to_relative_ms(tv); +} + +static int +ms_since(struct timeval * tv) +{ + return -timeval_to_relative_ms(tv); +} + +static void +rebuild(cubeb * ctx) +{ + nfds_t nfds; + int i; + nfds_t j; + cubeb_stream * stm; + + assert(ctx->rebuild); + + /* Always count context's control pipe fd. */ + nfds = 1; + for (i = 0; i < CUBEB_STREAM_MAX; ++i) { + stm = ctx->streams[i]; + if (stm) { + stm->fds = NULL; + if (stm->state == RUNNING) { + nfds += stm->nfds; + } + } + } + + free(ctx->fds); + ctx->fds = calloc(nfds, sizeof(struct pollfd)); + assert(ctx->fds); + ctx->nfds = nfds; + + /* Include context's control pipe fd. */ + ctx->fds[0].fd = ctx->control_fd_read; + ctx->fds[0].events = POLLIN | POLLERR; + + for (i = 0, j = 1; i < CUBEB_STREAM_MAX; ++i) { + stm = ctx->streams[i]; + if (stm && stm->state == RUNNING) { + memcpy(&ctx->fds[j], stm->saved_fds, stm->nfds * sizeof(struct pollfd)); + stm->fds = &ctx->fds[j]; + j += stm->nfds; + } + } + + ctx->rebuild = 0; +} + +static void +poll_wake(cubeb * ctx) +{ + if (write(ctx->control_fd_write, "x", 1) < 0) { + /* ignore write error */ + } +} + +static void +set_timeout(struct timeval * timeout, unsigned int ms) +{ + gettimeofday(timeout, NULL); + timeout->tv_sec += ms / 1000; + timeout->tv_usec += (ms % 1000) * 1000; +} + +static void +alsa_set_stream_state(cubeb_stream * stm, enum stream_state state) +{ + cubeb * ctx; + int r; + + ctx = stm->context; + stm->state = state; + r = pthread_cond_broadcast(&stm->cond); + assert(r == 0); + ctx->rebuild = 1; + poll_wake(ctx); +} + +static enum stream_state +alsa_refill_stream(cubeb_stream * stm) +{ + snd_pcm_sframes_t avail; + long got; + void * p; + int draining; + + draining = 0; + + pthread_mutex_lock(&stm->mutex); + + avail = snd_pcm_avail_update(stm->pcm); + if (avail < 0) { + snd_pcm_recover(stm->pcm, avail, 1); + avail = snd_pcm_avail_update(stm->pcm); + } + + /* Failed to recover from an xrun, this stream must be broken. */ + if (avail < 0) { + pthread_mutex_unlock(&stm->mutex); + stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR); + return ERROR; + } + + /* This should never happen. */ + if ((unsigned int) avail > stm->buffer_size) { + avail = stm->buffer_size; + } + + /* poll(2) claims this stream is active, so there should be some space + available to write. If avail is still zero here, the stream must be in + a funky state, bail and wait for another wakeup. */ + if (avail == 0) { + pthread_mutex_unlock(&stm->mutex); + return RUNNING; + } + + p = calloc(1, snd_pcm_frames_to_bytes(stm->pcm, avail)); + assert(p); + + pthread_mutex_unlock(&stm->mutex); + got = stm->data_callback(stm, stm->user_ptr, NULL, p, avail); + pthread_mutex_lock(&stm->mutex); + if (got < 0) { + pthread_mutex_unlock(&stm->mutex); + stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR); + free(p); + return ERROR; + } + if (got > 0) { + snd_pcm_sframes_t wrote; + + if (stm->params.format == CUBEB_SAMPLE_FLOAT32NE) { + float * b = (float *) p; + for (uint32_t i = 0; i < got * stm->params.channels; i++) { + b[i] *= stm->volume; + } + } else { + short * b = (short *) p; + for (uint32_t i = 0; i < got * stm->params.channels; i++) { + b[i] *= stm->volume; + } + } + wrote = snd_pcm_writei(stm->pcm, p, got); + if (wrote < 0) { + snd_pcm_recover(stm->pcm, wrote, 1); + wrote = snd_pcm_writei(stm->pcm, p, got); + } + assert(wrote >= 0 && wrote == got); + stm->write_position += wrote; + gettimeofday(&stm->last_activity, NULL); + } + if (got != avail) { + long buffer_fill = stm->buffer_size - (avail - got); + double buffer_time = (double) buffer_fill / stm->params.rate; + + /* Fill the remaining buffer with silence to guarantee one full period + has been written. */ + snd_pcm_writei(stm->pcm, (char *) p + got, avail - got); + + set_timeout(&stm->drain_timeout, buffer_time * 1000); + + draining = 1; + } + + free(p); + pthread_mutex_unlock(&stm->mutex); + return draining ? DRAINING : RUNNING; +} + +static int +alsa_run(cubeb * ctx) +{ + int r; + int timeout; + int i; + char dummy; + cubeb_stream * stm; + enum stream_state state; + + pthread_mutex_lock(&ctx->mutex); + + if (ctx->rebuild) { + rebuild(ctx); + } + + /* Wake up at least once per second for the watchdog. */ + timeout = 1000; + for (i = 0; i < CUBEB_STREAM_MAX; ++i) { + stm = ctx->streams[i]; + if (stm && stm->state == DRAINING) { + r = ms_until(&stm->drain_timeout); + if (r >= 0 && timeout > r) { + timeout = r; + } + } + } + + pthread_mutex_unlock(&ctx->mutex); + r = poll(ctx->fds, ctx->nfds, timeout); + pthread_mutex_lock(&ctx->mutex); + + if (r > 0) { + if (ctx->fds[0].revents & POLLIN) { + if (read(ctx->control_fd_read, &dummy, 1) < 0) { + /* ignore read error */ + } + + if (ctx->shutdown) { + pthread_mutex_unlock(&ctx->mutex); + return -1; + } + } + + for (i = 0; i < CUBEB_STREAM_MAX; ++i) { + stm = ctx->streams[i]; + /* We can't use snd_pcm_poll_descriptors_revents here because of + https://github.com/kinetiknz/cubeb/issues/135. */ + if (stm && stm->state == RUNNING && stm->fds && any_revents(stm->fds, stm->nfds)) { + alsa_set_stream_state(stm, PROCESSING); + pthread_mutex_unlock(&ctx->mutex); + state = alsa_refill_stream(stm); + pthread_mutex_lock(&ctx->mutex); + alsa_set_stream_state(stm, state); + } + } + } else if (r == 0) { + for (i = 0; i < CUBEB_STREAM_MAX; ++i) { + stm = ctx->streams[i]; + if (stm) { + if (stm->state == DRAINING && ms_since(&stm->drain_timeout) >= 0) { + alsa_set_stream_state(stm, INACTIVE); + stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_DRAINED); + } else if (stm->state == RUNNING && ms_since(&stm->last_activity) > CUBEB_WATCHDOG_MS) { + alsa_set_stream_state(stm, ERROR); + stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR); + } + } + } + } + + pthread_mutex_unlock(&ctx->mutex); + + return 0; +} + +static void * +alsa_run_thread(void * context) +{ + cubeb * ctx = context; + int r; + + do { + r = alsa_run(ctx); + } while (r >= 0); + + return NULL; +} + +static snd_config_t * +get_slave_pcm_node(snd_config_t * lconf, snd_config_t * root_pcm) +{ + int r; + snd_config_t * slave_pcm; + snd_config_t * slave_def; + snd_config_t * pcm; + char const * string; + char node_name[64]; + + slave_def = NULL; + + r = snd_config_search(root_pcm, "slave", &slave_pcm); + if (r < 0) { + return NULL; + } + + r = snd_config_get_string(slave_pcm, &string); + if (r >= 0) { + r = snd_config_search_definition(lconf, "pcm_slave", string, &slave_def); + if (r < 0) { + return NULL; + } + } + + do { + r = snd_config_search(slave_def ? slave_def : slave_pcm, "pcm", &pcm); + if (r < 0) { + break; + } + + r = snd_config_get_string(slave_def ? slave_def : slave_pcm, &string); + if (r < 0) { + break; + } + + r = snprintf(node_name, sizeof(node_name), "pcm.%s", string); + if (r < 0 || r > (int) sizeof(node_name)) { + break; + } + r = snd_config_search(lconf, node_name, &pcm); + if (r < 0) { + break; + } + + return pcm; + } while (0); + + if (slave_def) { + snd_config_delete(slave_def); + } + + return NULL; +} + +/* Work around PulseAudio ALSA plugin bug where the PA server forces a + higher than requested latency, but the plugin does not update its (and + ALSA's) internal state to reflect that, leading to an immediate underrun + situation. Inspired by WINE's make_handle_underrun_config. + Reference: http://mailman.alsa-project.org/pipermail/alsa-devel/2012-July/05 */ +static snd_config_t * +init_local_config_with_workaround(char const * pcm_name) +{ + int r; + snd_config_t * lconf; + snd_config_t * pcm_node; + snd_config_t * node; + char const * string; + char node_name[64]; + + lconf = NULL; + + if (snd_config == NULL) { + return NULL; + } + + r = snd_config_copy(&lconf, snd_config); + if (r < 0) { + return NULL; + } + + do { + r = snd_config_search_definition(lconf, "pcm", pcm_name, &pcm_node); + if (r < 0) { + break; + } + + r = snd_config_get_id(pcm_node, &string); + if (r < 0) { + break; + } + + r = snprintf(node_name, sizeof(node_name), "pcm.%s", string); + if (r < 0 || r > (int) sizeof(node_name)) { + break; + } + r = snd_config_search(lconf, node_name, &pcm_node); + if (r < 0) { + break; + } + + /* If this PCM has a slave, walk the slave configurations until we reach the bottom. */ + while ((node = get_slave_pcm_node(lconf, pcm_node)) != NULL) { + pcm_node = node; + } + + /* Fetch the PCM node's type, and bail out if it's not the PulseAudio plugin. */ + r = snd_config_search(pcm_node, "type", &node); + if (r < 0) { + break; + } + + r = snd_config_get_string(node, &string); + if (r < 0) { + break; + } + + if (strcmp(string, "pulse") != 0) { + break; + } + + /* Don't clobber an explicit existing handle_underrun value, set it only + if it doesn't already exist. */ + r = snd_config_search(pcm_node, "handle_underrun", &node); + if (r != -ENOENT) { + break; + } + + /* Disable pcm_pulse's asynchronous underrun handling. */ + r = snd_config_imake_integer(&node, "handle_underrun", 0); + if (r < 0) { + break; + } + + r = snd_config_add(pcm_node, node); + if (r < 0) { + break; + } + + return lconf; + } while (0); + + snd_config_delete(lconf); + + return NULL; +} + +static int +alsa_locked_pcm_open(snd_pcm_t ** pcm, snd_pcm_stream_t stream, snd_config_t * local_config) +{ + int r; + + pthread_mutex_lock(&cubeb_alsa_mutex); + if (local_config) { + r = snd_pcm_open_lconf(pcm, CUBEB_ALSA_PCM_NAME, stream, SND_PCM_NONBLOCK, local_config); + } else { + r = snd_pcm_open(pcm, CUBEB_ALSA_PCM_NAME, stream, SND_PCM_NONBLOCK); + } + pthread_mutex_unlock(&cubeb_alsa_mutex); + + return r; +} + +static int +alsa_locked_pcm_close(snd_pcm_t * pcm) +{ + int r; + + pthread_mutex_lock(&cubeb_alsa_mutex); + r = snd_pcm_close(pcm); + pthread_mutex_unlock(&cubeb_alsa_mutex); + + return r; +} + +static int +alsa_register_stream(cubeb * ctx, cubeb_stream * stm) +{ + int i; + + pthread_mutex_lock(&ctx->mutex); + for (i = 0; i < CUBEB_STREAM_MAX; ++i) { + if (!ctx->streams[i]) { + ctx->streams[i] = stm; + break; + } + } + pthread_mutex_unlock(&ctx->mutex); + + return i == CUBEB_STREAM_MAX; +} + +static void +alsa_unregister_stream(cubeb_stream * stm) +{ + cubeb * ctx; + int i; + + ctx = stm->context; + + pthread_mutex_lock(&ctx->mutex); + for (i = 0; i < CUBEB_STREAM_MAX; ++i) { + if (ctx->streams[i] == stm) { + ctx->streams[i] = NULL; + break; + } + } + pthread_mutex_unlock(&ctx->mutex); +} + +static void +silent_error_handler(char const * file, int line, char const * function, + int err, char const * fmt, ...) +{ + (void)file; + (void)line; + (void)function; + (void)err; + (void)fmt; +} + +/*static*/ int +alsa_init(cubeb ** context, char const * context_name) +{ + (void)context_name; + cubeb * ctx; + int r; + int i; + int fd[2]; + pthread_attr_t attr; + snd_pcm_t * dummy; + + assert(context); + *context = NULL; + + pthread_mutex_lock(&cubeb_alsa_mutex); + if (!cubeb_alsa_error_handler_set) { + snd_lib_error_set_handler(silent_error_handler); + cubeb_alsa_error_handler_set = 1; + } + pthread_mutex_unlock(&cubeb_alsa_mutex); + + ctx = calloc(1, sizeof(*ctx)); + assert(ctx); + + ctx->ops = &alsa_ops; + + r = pthread_mutex_init(&ctx->mutex, NULL); + assert(r == 0); + + r = pipe(fd); + assert(r == 0); + + for (i = 0; i < 2; ++i) { + fcntl(fd[i], F_SETFD, fcntl(fd[i], F_GETFD) | FD_CLOEXEC); + fcntl(fd[i], F_SETFL, fcntl(fd[i], F_GETFL) | O_NONBLOCK); + } + + ctx->control_fd_read = fd[0]; + ctx->control_fd_write = fd[1]; + + /* Force an early rebuild when alsa_run is first called to ensure fds and + nfds have been initialized. */ + ctx->rebuild = 1; + + r = pthread_attr_init(&attr); + assert(r == 0); + + r = pthread_attr_setstacksize(&attr, 256 * 1024); + assert(r == 0); + + r = pthread_create(&ctx->thread, &attr, alsa_run_thread, ctx); + assert(r == 0); + + r = pthread_attr_destroy(&attr); + assert(r == 0); + + /* Open a dummy PCM to force the configuration space to be evaluated so that + init_local_config_with_workaround can find and modify the default node. */ + r = alsa_locked_pcm_open(&dummy, SND_PCM_STREAM_PLAYBACK, NULL); + if (r >= 0) { + alsa_locked_pcm_close(dummy); + } + ctx->is_pa = 0; + pthread_mutex_lock(&cubeb_alsa_mutex); + ctx->local_config = init_local_config_with_workaround(CUBEB_ALSA_PCM_NAME); + pthread_mutex_unlock(&cubeb_alsa_mutex); + if (ctx->local_config) { + ctx->is_pa = 1; + r = alsa_locked_pcm_open(&dummy, SND_PCM_STREAM_PLAYBACK, ctx->local_config); + /* If we got a local_config, we found a PA PCM. If opening a PCM with that + config fails with EINVAL, the PA PCM is too old for this workaround. */ + if (r == -EINVAL) { + pthread_mutex_lock(&cubeb_alsa_mutex); + snd_config_delete(ctx->local_config); + pthread_mutex_unlock(&cubeb_alsa_mutex); + ctx->local_config = NULL; + } else if (r >= 0) { + alsa_locked_pcm_close(dummy); + } + } + + *context = ctx; + + return CUBEB_OK; +} + +static char const * +alsa_get_backend_id(cubeb * ctx) +{ + (void)ctx; + return "alsa"; +} + +static void +alsa_destroy(cubeb * ctx) +{ + int r; + + assert(ctx); + + pthread_mutex_lock(&ctx->mutex); + ctx->shutdown = 1; + poll_wake(ctx); + pthread_mutex_unlock(&ctx->mutex); + + r = pthread_join(ctx->thread, NULL); + assert(r == 0); + + close(ctx->control_fd_read); + close(ctx->control_fd_write); + pthread_mutex_destroy(&ctx->mutex); + free(ctx->fds); + + if (ctx->local_config) { + pthread_mutex_lock(&cubeb_alsa_mutex); + snd_config_delete(ctx->local_config); + pthread_mutex_unlock(&cubeb_alsa_mutex); + } + + free(ctx); +} + +static void alsa_stream_destroy(cubeb_stream * stm); + +static int +alsa_stream_init(cubeb * ctx, cubeb_stream ** stream, char const * stream_name, + cubeb_devid input_device, + cubeb_stream_params * input_stream_params, + cubeb_devid output_device, + cubeb_stream_params * output_stream_params, + unsigned int latency_frames, + cubeb_data_callback data_callback, cubeb_state_callback state_callback, + void * user_ptr) +{ + (void)stream_name; + cubeb_stream * stm; + int r; + snd_pcm_format_t format; + snd_pcm_uframes_t period_size; + int latency_us = 0; + + + assert(ctx && stream); + + if (input_stream_params) { + /* Capture support not yet implemented. */ + return CUBEB_ERROR_NOT_SUPPORTED; + } + + if (input_device || output_device) { + /* Device selection not yet implemented. */ + return CUBEB_ERROR_DEVICE_UNAVAILABLE; + } + + *stream = NULL; + + switch (output_stream_params->format) { + case CUBEB_SAMPLE_S16LE: + format = SND_PCM_FORMAT_S16_LE; + break; + case CUBEB_SAMPLE_S16BE: + format = SND_PCM_FORMAT_S16_BE; + break; + case CUBEB_SAMPLE_FLOAT32LE: + format = SND_PCM_FORMAT_FLOAT_LE; + break; + case CUBEB_SAMPLE_FLOAT32BE: + format = SND_PCM_FORMAT_FLOAT_BE; + break; + default: + return CUBEB_ERROR_INVALID_FORMAT; + } + + pthread_mutex_lock(&ctx->mutex); + if (ctx->active_streams >= CUBEB_STREAM_MAX) { + pthread_mutex_unlock(&ctx->mutex); + return CUBEB_ERROR; + } + ctx->active_streams += 1; + pthread_mutex_unlock(&ctx->mutex); + + stm = calloc(1, sizeof(*stm)); + assert(stm); + + stm->context = ctx; + stm->data_callback = data_callback; + stm->state_callback = state_callback; + stm->user_ptr = user_ptr; + stm->params = *output_stream_params; + stm->state = INACTIVE; + stm->volume = 1.0; + + r = pthread_mutex_init(&stm->mutex, NULL); + assert(r == 0); + + r = alsa_locked_pcm_open(&stm->pcm, SND_PCM_STREAM_PLAYBACK, ctx->local_config); + if (r < 0) { + alsa_stream_destroy(stm); + return CUBEB_ERROR; + } + + r = snd_pcm_nonblock(stm->pcm, 1); + assert(r == 0); + + latency_us = latency_frames * 1e6 / stm->params.rate; + + /* Ugly hack: the PA ALSA plugin allows buffer configurations that can't + possibly work. See https://bugzilla.mozilla.org/show_bug.cgi?id=761274. + Only resort to this hack if the handle_underrun workaround failed. */ + if (!ctx->local_config && ctx->is_pa) { + const int min_latency = 5e5; + latency_us = latency_us < min_latency ? min_latency: latency_us; + } + + r = snd_pcm_set_params(stm->pcm, format, SND_PCM_ACCESS_RW_INTERLEAVED, + stm->params.channels, stm->params.rate, 1, + latency_us); + if (r < 0) { + alsa_stream_destroy(stm); + return CUBEB_ERROR_INVALID_FORMAT; + } + + r = snd_pcm_get_params(stm->pcm, &stm->buffer_size, &period_size); + assert(r == 0); + + stm->nfds = snd_pcm_poll_descriptors_count(stm->pcm); + assert(stm->nfds > 0); + + stm->saved_fds = calloc(stm->nfds, sizeof(struct pollfd)); + assert(stm->saved_fds); + r = snd_pcm_poll_descriptors(stm->pcm, stm->saved_fds, stm->nfds); + assert((nfds_t) r == stm->nfds); + + r = pthread_cond_init(&stm->cond, NULL); + assert(r == 0); + + if (alsa_register_stream(ctx, stm) != 0) { + alsa_stream_destroy(stm); + return CUBEB_ERROR; + } + + *stream = stm; + + return CUBEB_OK; +} + +static void +alsa_stream_destroy(cubeb_stream * stm) +{ + int r; + cubeb * ctx; + + assert(stm && (stm->state == INACTIVE || + stm->state == ERROR || + stm->state == DRAINING)); + + ctx = stm->context; + + pthread_mutex_lock(&stm->mutex); + if (stm->pcm) { + if (stm->state == DRAINING) { + snd_pcm_drain(stm->pcm); + } + alsa_locked_pcm_close(stm->pcm); + stm->pcm = NULL; + } + free(stm->saved_fds); + pthread_mutex_unlock(&stm->mutex); + pthread_mutex_destroy(&stm->mutex); + + r = pthread_cond_destroy(&stm->cond); + assert(r == 0); + + alsa_unregister_stream(stm); + + pthread_mutex_lock(&ctx->mutex); + assert(ctx->active_streams >= 1); + ctx->active_streams -= 1; + pthread_mutex_unlock(&ctx->mutex); + + free(stm); +} + +static int +alsa_get_max_channel_count(cubeb * ctx, uint32_t * max_channels) +{ + int r; + cubeb_stream * stm; + snd_pcm_hw_params_t* hw_params; + cubeb_stream_params params; + params.rate = 44100; + params.format = CUBEB_SAMPLE_FLOAT32NE; + params.channels = 2; + + snd_pcm_hw_params_alloca(&hw_params); + + assert(ctx); + + r = alsa_stream_init(ctx, &stm, "", NULL, NULL, NULL, ¶ms, 100, NULL, NULL, NULL); + if (r != CUBEB_OK) { + return CUBEB_ERROR; + } + + r = snd_pcm_hw_params_any(stm->pcm, hw_params); + if (r < 0) { + return CUBEB_ERROR; + } + + r = snd_pcm_hw_params_get_channels_max(hw_params, max_channels); + if (r < 0) { + return CUBEB_ERROR; + } + + alsa_stream_destroy(stm); + + return CUBEB_OK; +} + +static int +alsa_get_preferred_sample_rate(cubeb * ctx, uint32_t * rate) { + (void)ctx; + int r, dir; + snd_pcm_t * pcm; + snd_pcm_hw_params_t * hw_params; + + snd_pcm_hw_params_alloca(&hw_params); + + /* get a pcm, disabling resampling, so we get a rate the + * hardware/dmix/pulse/etc. supports. */ + r = snd_pcm_open(&pcm, CUBEB_ALSA_PCM_NAME, SND_PCM_STREAM_PLAYBACK, SND_PCM_NO_AUTO_RESAMPLE); + if (r < 0) { + return CUBEB_ERROR; + } + + r = snd_pcm_hw_params_any(pcm, hw_params); + if (r < 0) { + snd_pcm_close(pcm); + return CUBEB_ERROR; + } + + r = snd_pcm_hw_params_get_rate(hw_params, rate, &dir); + if (r >= 0) { + /* There is a default rate: use it. */ + snd_pcm_close(pcm); + return CUBEB_OK; + } + + /* Use a common rate, alsa may adjust it based on hw/etc. capabilities. */ + *rate = 44100; + + r = snd_pcm_hw_params_set_rate_near(pcm, hw_params, rate, NULL); + if (r < 0) { + snd_pcm_close(pcm); + return CUBEB_ERROR; + } + + snd_pcm_close(pcm); + + return CUBEB_OK; +} + +static int +alsa_get_min_latency(cubeb * ctx, cubeb_stream_params params, uint32_t * latency_frames) +{ + (void)ctx; + /* 40ms is found to be an acceptable minimum, even on a super low-end + * machine. */ + *latency_frames = 40 * params.rate / 1000; + + return CUBEB_OK; +} + +static int +alsa_stream_start(cubeb_stream * stm) +{ + cubeb * ctx; + + assert(stm); + ctx = stm->context; + + pthread_mutex_lock(&stm->mutex); + snd_pcm_pause(stm->pcm, 0); + gettimeofday(&stm->last_activity, NULL); + pthread_mutex_unlock(&stm->mutex); + + pthread_mutex_lock(&ctx->mutex); + if (stm->state != INACTIVE) { + pthread_mutex_unlock(&ctx->mutex); + return CUBEB_ERROR; + } + alsa_set_stream_state(stm, RUNNING); + pthread_mutex_unlock(&ctx->mutex); + + return CUBEB_OK; +} + +static int +alsa_stream_stop(cubeb_stream * stm) +{ + cubeb * ctx; + int r; + + assert(stm); + ctx = stm->context; + + pthread_mutex_lock(&ctx->mutex); + while (stm->state == PROCESSING) { + r = pthread_cond_wait(&stm->cond, &ctx->mutex); + assert(r == 0); + } + + alsa_set_stream_state(stm, INACTIVE); + pthread_mutex_unlock(&ctx->mutex); + + pthread_mutex_lock(&stm->mutex); + snd_pcm_pause(stm->pcm, 1); + pthread_mutex_unlock(&stm->mutex); + + return CUBEB_OK; +} + +static int +alsa_stream_get_position(cubeb_stream * stm, uint64_t * position) +{ + snd_pcm_sframes_t delay; + + assert(stm && position); + + pthread_mutex_lock(&stm->mutex); + + delay = -1; + if (snd_pcm_state(stm->pcm) != SND_PCM_STATE_RUNNING || + snd_pcm_delay(stm->pcm, &delay) != 0) { + *position = stm->last_position; + pthread_mutex_unlock(&stm->mutex); + return CUBEB_OK; + } + + assert(delay >= 0); + + *position = 0; + if (stm->write_position >= (snd_pcm_uframes_t) delay) { + *position = stm->write_position - delay; + } + + stm->last_position = *position; + + pthread_mutex_unlock(&stm->mutex); + return CUBEB_OK; +} + +static int +alsa_stream_get_latency(cubeb_stream * stm, uint32_t * latency) +{ + snd_pcm_sframes_t delay; + /* This function returns the delay in frames until a frame written using + snd_pcm_writei is sent to the DAC. The DAC delay should be < 1ms anyways. */ + if (snd_pcm_delay(stm->pcm, &delay)) { + return CUBEB_ERROR; + } + + *latency = delay; + + return CUBEB_OK; +} + +static int +alsa_stream_set_volume(cubeb_stream * stm, float volume) +{ + /* setting the volume using an API call does not seem very stable/supported */ + pthread_mutex_lock(&stm->mutex); + stm->volume = volume; + pthread_mutex_unlock(&stm->mutex); + + return CUBEB_OK; +} + +static struct cubeb_ops const alsa_ops = { + .init = alsa_init, + .get_backend_id = alsa_get_backend_id, + .get_max_channel_count = alsa_get_max_channel_count, + .get_min_latency = alsa_get_min_latency, + .get_preferred_sample_rate = alsa_get_preferred_sample_rate, + .enumerate_devices = NULL, + .destroy = alsa_destroy, + .stream_init = alsa_stream_init, + .stream_destroy = alsa_stream_destroy, + .stream_start = alsa_stream_start, + .stream_stop = alsa_stream_stop, + .stream_get_position = alsa_stream_get_position, + .stream_get_latency = alsa_stream_get_latency, + .stream_set_volume = alsa_stream_set_volume, + .stream_set_panning = NULL, + .stream_get_current_device = NULL, + .stream_device_destroy = NULL, + .stream_register_device_changed_callback = NULL, + .register_device_collection_changed = NULL +}; |