* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*/
+/** @file clients/playrtp.c
+ * @brief RTP player
+ *
+ * This RTP player supports Linux (ALSA) and Darwin (Core Audio) systems.
+ */
#include <config.h>
#include "types.h"
#include <pthread.h>
#include <locale.h>
#include <sys/uio.h>
+#include <string.h>
#include "log.h"
#include "mem.h"
#include "syscalls.h"
#include "rtp.h"
#include "defs.h"
+#include "vector.h"
+#include "heap.h"
#if HAVE_COREAUDIO_AUDIOHARDWARE_H
# include <CoreAudio/AudioHardware.h>
* We'll stop reading from the network if we have this many samples. */
static unsigned maxbuffer;
-/** @brief Number of samples to infill by in one go */
+/** @brief Number of samples to infill by in one go
+ *
+ * This is an upper bound - in practice we expxect the underlying audio API to
+ * only ask for a much smaller number of samples in any one go.
+ */
#define INFILL_SAMPLES (44100 * 2) /* 1s */
-/** @brief Received packet */
+/** @brief Received packet
+ *
+ * Received packets are kept in a binary heap (see @ref pheap) ordered by
+ * timestamp.
+ */
struct packet {
/** @brief Number of samples in this packet */
uint32_t nsamples;
/** @brief Timestamp from RTP packet
*
- * NB that "timestamps" are really sample counters.*/
+ * NB that "timestamps" are really sample counters. Use lt() or lt_packet()
+ * to compare timestamps.
+ */
uint32_t timestamp;
- /** @brief Raw sample data */
+ /** @brief Raw sample data
+ *
+ * Only the first @p nsamples samples are defined; the rest is uninitialized
+ * data.
+ */
unsigned char samples_raw[MAXSAMPLES * MAXSAMPLESIZE];
};
-/** @brief Total number of samples available */
-static unsigned long nsamples;
-
-/** @brief Mapping of sequence numbers to packets
+/** @brief Return true iff \f$a < b\f$ in sequence-space arithmetic
*
- * This isn't very efficient - 256KB on 32-bit machines, 512KB if you do a
- * 64-bit build for some reason. It can be optimized later if need be. */
-static struct packet *packets[65536];
+ * Specifically it returns true if \f$(a-b) mod 2^{32} < 2^{31}\f$.
+ *
+ * See also lt_packet().
+ */
+static inline int lt(uint32_t a, uint32_t b) {
+ return (uint32_t)(a - b) & 0x80000000;
+}
-/** @brief Total number of packets */
-static unsigned npackets;
+/** @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 Ordering for packets, used by @ref pheap */
+static inline int lt_packet(const struct packet *a, const struct packet *b) {
+ return lt(a->timestamp, b->timestamp);
+}
+
+/** @struct pheap
+ * @brief Binary heap of packets ordered by timestamp */
+HEAP_TYPE(pheap, struct packet *, lt_packet);
+
+/** @brief Binary heap of received packets */
+static struct pheap packets;
+
+/** @brief Total number of samples available */
+static unsigned long nsamples;
/** @brief Timestamp of next packet to play.
*
* This is true when playing and false when just buffering. */
static int active;
-/** @brief Sequence number of next packet we expxect to play */
-static uint16_t sequence;
-
/** @brief Structure of free packet list */
union free_packet {
struct packet p;
union free_packet *next;
};
-/** @brief Linked list of free packets */
+/** @brief Linked list of free packets
+ *
+ * This is a linked list of formerly used packets. For preference we re-use
+ * packets that have already been used rather than unused ones, to limit the
+ * size of the program's working set. If there are no free packets in the list
+ * we try @ref next_free_packet instead.
+ *
+ * Must hold @ref lock when accessing this.
+ */
static union free_packet *free_packets;
-/** @brief Array of new free packets */
+/** @brief Array of new free packets
+ *
+ * There are @ref count_free_packets ready to use at this address. If there
+ * are none left we allocate more memory.
+ *
+ * Must hold @ref lock when accessing this.
+ */
static union free_packet *next_free_packet;
-/** @brief Count of new free packets */
+/** @brief Count of new free packets at @ref next_free_packet
+ *
+ * Must hold @ref lock when accessing this.
+ */
static size_t count_free_packets;
-/** @brief Lock protecting @ref packets */
+/** @brief Lock protecting @ref packets
+ *
+ * This also protects the packet memory allocation infrastructure, @ref
+ * free_packets and @ref next_free_packet. */
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
/** @brief Condition variable signalled whenever @ref packets is changed */
free_packets = u;
}
-/** @brief Return true iff a < b in sequence-space arithmetic */
-static inline int lt(uint32_t a, uint32_t b) {
- 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 Drop the packet at the head of the queue */
-static void drop_packet(unsigned sequence) {
- if(packets[sequence]) {
- nsamples -= packets[sequence]->nsamples;
- free_packet(packets[sequence]);
- packets[sequence] = 0;
+/** @brief Drop the first packet
+ *
+ * Assumes that @ref lock is held.
+ */
+static void drop_first_packet(void) {
+ if(pheap_count(&packets)) {
+ struct packet *const p = pheap_remove(&packets);
+ nsamples -= p->nsamples;
+ free_packet(p);
pthread_cond_broadcast(&cond);
- --npackets;
}
}
while(nsamples >= maxbuffer)
pthread_cond_wait(&cond, &lock);
}
- /* If there's a packet there already we overwrite it; perhaps it is left
- * over from an earlier stage. */
- drop_packet(seq);
- /* Record this packet */
- packets[seq] = p;
- /* If we currently have no idea where to start playing, this is it */
- if(!npackets)
- sequence = seq;
- ++npackets;
+ /* Add the packet to the heap */
+ pheap_insert(&packets, p);
nsamples += p->nsamples;
pthread_cond_broadcast(&cond);
pthread_mutex_unlock(&lock);
UInt32 nbuffers = outOutputData->mNumberBuffers;
AudioBuffer *ab = outOutputData->mBuffers;
const struct packet *p;
+ uint32_t samples_available;
pthread_mutex_lock(&lock);
while(nbuffers > 0) {
while(samplesOutLeft > 0) {
/* Look for a suitable packet, dropping any unsuitable ones along the
* way. Unsuitable packets are ones that are in the past. */
- while(npackets
- && (!packets[sequence]
- || le(packets[sequence]->timestamp
- + packets[sequence]->nsamples,
- next_timestamp)))
- drop_packet(sequence++);
- p = packets[sequence];
- if(p) {
- if(contains(p, next_timestamp)) {
- /* This packet is suitable */
- const uint32_t packet_end = p->timestamp + p->nsamples;
- const uint32_t offset = next_timestamp - p->timestamp;
- const uint16_t *ptr =
- (void *)(p->samples_raw + offset * sizeof (uint16_t));
- uint32_t samples_available = packet_end - next_timestamp;
- if(samples_available > samplesOutLeft)
- samples_available = samplesOutLeft;
- next_timestamp += samples_available;
- samplesOutLeft -= samples_available;
- while(samples_available-- > 0)
- *samplesOut++ = (int16_t)ntohs(*ptr++) * (0.5 / 32767);
- /* We don't bother junking the packet or advancing sequence - that'll
- * be dealt with next time round */
- continue;
- }
+ while(pheap_count(&packets)) {
+ p = pheap_first(&packets);
+ if(le(p->timestamp + p->nsamples, next_timestamp))
+ /* This packet is in the past. Drop it and try another one. */
+ drop_first_packet();
+ else
+ /* This packet is NOT in the past. (It might be in the future
+ * however.) */
+ break;
}
- /* We didn't find a suitable packet (though there might still be
- * unsuitable ones). We infill with 0s. */
- if(p) {
- /* There is a next packet, only infill up to that point */
- uint32_t samples_available = p->timestamp - next_timestamp;
-
+ p = pheap_count(&packets) ? pheap_first(&packets) : 0;
+ if(p && contains(p, next_timestamp)) {
+ /* This packet is ready to play */
+ const uint32_t packet_end = p->timestamp + p->nsamples;
+ const uint32_t offset = next_timestamp - p->timestamp;
+ const uint16_t *ptr =
+ (void *)(p->samples_raw + offset * sizeof (uint16_t));
+
+ samples_available = packet_end - next_timestamp;
+ if(samples_available > samplesOutLeft)
+ samples_available = samplesOutLeft;
+ next_timestamp += samples_available;
+ samplesOutLeft -= samples_available;
+ while(samples_available-- > 0)
+ *samplesOut++ = (int16_t)ntohs(*ptr++) * (0.5 / 32767);
+ /* We don't bother junking the packet - that'll be dealt with next time
+ * round */
+ } else {
+ /* No packet is ready to play (and there might be no packet at all) */
+ samples_available = p ? p->timestamp - next_timestamp
+ : samplesOutLeft;
if(samples_available > samplesOutLeft)
samples_available = samplesOutLeft;
info("infill by %"PRIu32, samples_available);
- /* Convniently the buffer is 0 to start with */
+ /* Conveniently the buffer is 0 to start with */
next_timestamp += samples_available;
samplesOut += samples_available;
samplesOutLeft -= samples_available;
- } else {
- /* There's no next packet at all */
- info("infilled by %zu", samplesOutLeft);
- next_timestamp += samplesOutLeft;
- samplesOut += samplesOutLeft;
- samplesOutLeft = 0;
}
}
++ab;
fatal(0, "error calling snd_pcm_prepare: %d", err);
prepared = 1;
}
- assert(sequence != -1);
- /* Start at the first available packet */
- next_timestamp = packets[sequence]->timestamp;
active = 1;
infilling = 0;
escape = 0;
pthread_cond_wait(&cond, &lock);
/* Start playing now */
info("Playing...");
- next_timestamp = packets[sequence]->timestamp;
+ next_timestamp = pheap_first(&packets)->timestamp;
active = 1;
status = AudioDeviceStart(adid, adioproc);
if(status)
~mdw / disorder / blobdiff