* We'll only start playing when this many samples are available. */
static unsigned readahead = 4 * 2 * 44100; /* 4 seconds */
+/** @brief Number of samples to infill by in one go */
+#define INFILL_SAMPLES (44100 * 2) /* 1s */
+
#define MAXBUFFER (3 * 88200) /* maximum buffer contents */
/** @brief Received packet
* or mis-ordered there may be gaps at any given moment. */
struct packet *next;
/** @brief Number of samples in this packet */
- int nsamples;
- /** @brief Number of samples used from this packet */
- int nused;
+ uint32_t nsamples;
/** @brief Timestamp from RTP packet
*
* NB that "timestamps" are really sample counters.*/
return (uint32_t)(a - b) & 0x80000000;
}
+/** @brief Return true iff a >= b in sequence-space arithmetic */
+static inline int ge(uint32_t a, uint32_t b) {
+ return !lt(a, b);
+}
+
+/** @brief Return true iff a > b in sequence-space arithmetic */
+static inline int gt(uint32_t a, uint32_t b) {
+ return lt(b, a);
+}
+
+/** @brief Return true iff a <= b in sequence-space arithmetic */
+static inline int le(uint32_t a, uint32_t b) {
+ return !lt(b, a);
+}
+
/** @brief Background thread collecting samples
*
* This function collects samples, perhaps converts them to the target format,
/* Ignore too-short packets */
if((size_t)n <= sizeof (struct rtp_header))
continue;
- p->nused = 0;
p->timestamp = ntohl(packet.header.timestamp);
/* Ignore packets in the past */
- if(active && lt(p->timestamp, next_timestamp))
+ if(active && lt(p->timestamp, next_timestamp)) {
+ info("dropping old packet, timestamp=%"PRIx32" < %"PRIx32,
+ p->timestamp, next_timestamp);
continue;
+ }
/* Convert to target format */
switch(packet.header.mpt & 0x7F) {
case 10:
size_t samples_written;
int prepared = 1;
int err;
- int infilling = 0;
+ int infilling = 0, escape = 0;
+ time_t logged, now;
+ uint32_t packet_start, packet_end;
/* Open ALSA */
if((err = snd_pcm_open(&pcm,
/* Ready to go */
+ time(&logged);
pthread_mutex_lock(&lock);
for(;;) {
/* Wait for the buffer to fill up a bit */
next_timestamp = packets->timestamp;
active = 1;
infilling = 0;
+ escape = 0;
info("Playing...");
/* Wait until the buffer empties out */
- while(nsamples >= minbuffer) {
+ while(nsamples >= minbuffer && !escape) {
+ time(&now);
+ if(now > logged + 10) {
+ logged = now;
+ info("%lu samples in buffer (%lus)", nsamples,
+ nsamples / (44100 * 2));
+ }
+ if(packets
+ && ge(next_timestamp, packets->timestamp + packets->nsamples)) {
+ struct packet *p = packets;
+
+ info("dropping buffered past packet %"PRIx32" < %"PRIx32,
+ packets->timestamp, next_timestamp);
+
+ packets = p->next;
+ if(packets)
+ assert(lt(p->timestamp, packets->timestamp));
+ nsamples -= p->nsamples;
+ free(p);
+ pthread_cond_broadcast(&cond);
+ continue;
+ }
/* Wait for ALSA to ask us for more data */
pthread_mutex_unlock(&lock);
snd_pcm_wait(pcm, -1);
pthread_mutex_lock(&lock);
/* ALSA is ready for more data */
- if(packets && packets->timestamp + packets->nused == next_timestamp) {
- /* Hooray, we have a packet we can play */
- const size_t samples_available = packets->nsamples - packets->nused;
+ packet_start = packets->timestamp;
+ packet_end = packets->timestamp + packets->nsamples;
+ if(ge(next_timestamp, packet_start)
+ && lt(next_timestamp, packet_end)) {
+ /* The target timestamp is somewhere in this packet */
+ const uint32_t offset = next_timestamp - packets->timestamp;
+ const uint32_t samples_available = (packets->timestamp + packets->nsamples) - next_timestamp;
const size_t frames_available = samples_available / 2;
frames_written = snd_pcm_writei(pcm,
- packets->samples_raw + packets->nused,
+ packets->samples_raw + offset,
frames_available);
if(frames_written < 0) {
- if(frames_written != -EAGAIN)
+ switch(frames_written) {
+ case -EAGAIN:
+ info("snd_pcm_wait() returned but we got -EAGAIN!");
+ break;
+ case -EPIPE:
+ error(0, "error calling snd_pcm_writei: %ld",
+ (long)frames_written);
+ escape = 1;
+ break;
+ default:
fatal(0, "error calling snd_pcm_writei: %ld",
(long)frames_written);
+ }
} else {
samples_written = frames_written * 2;
- packets->nused += samples_written;
next_timestamp += samples_written;
- if(packets->nused == packets->nsamples) {
+ if(ge(next_timestamp, packet_end)) {
/* We're done with this packet */
struct packet *p = packets;
packets = p->next;
+ if(packets)
+ assert(lt(p->timestamp, packets->timestamp));
nsamples -= p->nsamples;
free(p);
pthread_cond_broadcast(&cond);
}
} else {
/* We don't have anything to play! We'd better play some 0s. */
- static const uint16_t zeros[1024];
- size_t samples_available = 1024, frames_available;
+ static const uint16_t zeros[INFILL_SAMPLES];
+ size_t samples_available = INFILL_SAMPLES, frames_available;
- if(!infilling) {
- info("Infilling...");
- infilling = 1;
- }
- if(packets && next_timestamp + samples_available > packets->timestamp)
+ /* If the maximum infill would take us past the start of the next
+ * packet then we truncate the infill to the right amount. */
+ if(lt(packets->timestamp,
+ next_timestamp + samples_available))
samples_available = packets->timestamp - next_timestamp;
+ if((int)samples_available < 0) {
+ info("packets->timestamp: %"PRIx32" next_timestamp: %"PRIx32" next+max: %"PRIx32" available: %"PRIx32,
+ packets->timestamp, next_timestamp,
+ next_timestamp + INFILL_SAMPLES, samples_available);
+ }
frames_available = samples_available / 2;
+ if(!infilling) {
+ info("Infilling %d samples, next=%"PRIx32" but packet=%"PRIx32,
+ samples_available, next_timestamp, packets->timestamp);
+ //infilling++;
+ }
frames_written = snd_pcm_writei(pcm,
zeros,
frames_available);
if(frames_written < 0) {
- if(frames_written != -EAGAIN)
+ switch(frames_written) {
+ case -EAGAIN:
+ info("snd_pcm_wait() returned but we got -EAGAIN!");
+ break;
+ case -EPIPE:
+ error(0, "error calling snd_pcm_writei: %ld",
+ (long)frames_written);
+ escape = 1;
+ break;
+ default:
fatal(0, "error calling snd_pcm_writei: %ld",
(long)frames_written);
+ }
} else {
samples_written = frames_written * 2;
next_timestamp += samples_written;
pthread_mutex_unlock(&lock);
if((err = snd_pcm_nonblock(pcm, 0)))
fatal(0, "error calling snd_pcm_nonblock: %d", err);
- if((err = snd_pcm_drain(pcm)))
- fatal(0, "error calling snd_pcm_drain: %d", err);
+ if(escape) {
+ if((err = snd_pcm_drop(pcm)))
+ fatal(0, "error calling snd_pcm_drop: %d", err);
+ escape = 0;
+ } else
+ if((err = snd_pcm_drain(pcm)))
+ fatal(0, "error calling snd_pcm_drain: %d", err);
if((err = snd_pcm_nonblock(pcm, 1)))
fatal(0, "error calling snd_pcm_nonblock: %d", err);
prepared = 0;
~mdw / disorder / commitdiff