X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/disorder/blobdiff_plain/24d0936b77d1bd2ed839cea7d7408dd7eadb0065..572d74ba4446a663aad2d410e83269fd309c7a63:/server/speaker.c diff --git a/server/speaker.c b/server/speaker.c index 4d21381..6cb89ed 100644 --- a/server/speaker.c +++ b/server/speaker.c @@ -726,7 +726,7 @@ static void play(size_t frames) { * AVT profile (RFC3551). */ if(idled) { - /* There's been a gap. Fix up the RTP time accordingly. */ + /* There may have been a gap. Fix up the RTP time accordingly. */ struct timeval now; uint64_t delta; uint64_t target_rtp_time; @@ -739,13 +739,48 @@ static void play(size_t frames) { target_rtp_time = (delta * playing->format.rate * playing->format.channels) / 1000000; /* Overflows at ~6 years uptime with 44100Hz stereo */ - if(target_rtp_time > rtp_time) + + /* rtp_time is the number of samples we've played. NB that we play + * RTP_AHEAD_MS ahead of ourselves, so it may legitimately be ahead of + * the value we deduce from time comparison. + * + * Suppose we have 1s track started at t=0, and another track begins to + * play at t=2s. Suppose RTP_AHEAD_MS=1000 and 44100Hz stereo. In that + * case we'll send 1s of audio as fast as we can, giving rtp_time=88200. + * rtp_time stops at this point. + * + * At t=2s we'll have calculated target_rtp_time=176400. In this case we + * set rtp_time=176400 and the player can correctly conclude that it + * should leave 1s between the tracks. + * + * Suppose instead that the second track arrives at t=0.5s, and that + * we've managed to transmit the whole of the first track already. We'll + * have target_rtp_time=44100. + * + * The desired behaviour is to play the second track back to back with + * first. In this case therefore we do not modify rtp_time. + * + * Is it ever right to reduce rtp_time? No; for that would imply + * transmitting packets with overlapping timestamp ranges, which does not + * make sense. + */ + if(target_rtp_time > rtp_time) { + /* More time has elapsed than we've transmitted samples. That implies + * we've been 'sending' silence. */ info("advancing rtp_time by %"PRIu64" samples", target_rtp_time - rtp_time); - else if(target_rtp_time < rtp_time) - info("reversing rtp_time by %"PRIu64" samples", - rtp_time - target_rtp_time); - rtp_time = target_rtp_time; + rtp_time = target_rtp_time; + } else if(target_rtp_time < rtp_time) { + const int64_t samples_ahead = ((uint64_t)RTP_AHEAD_MS + * config->sample_format.rate + * config->sample_format.channels + / 1000); + + if(target_rtp_time + samples_ahead < rtp_time) { + info("reversing rtp_time by %"PRIu64" samples", + rtp_time - target_rtp_time); + } + } } header.vpxcc = 2 << 6; /* V=2, P=0, X=0, CC=0 */ header.seq = htons(rtp_seq++); @@ -843,10 +878,21 @@ static int addfd(int fd, int events) { return -1; } -int main(int argc, char **argv) { - int n, fd, stdin_slot, alsa_slots, cmdfd_slot, bfd_slot, poke, timeout; - struct track *t; - struct speaker_message sm; +#if API_ALSA +/** @brief ALSA backend initialization */ +static void alsa_init(void) { + info("selected ALSA backend"); +} +#endif + +/** @brief Command backend initialization */ +static void command_init(void) { + info("selected command backend"); + fork_cmd(); +} + +/** @brief Network backend initialization */ +static void network_init(void) { struct addrinfo *res, *sres; static const struct addrinfo pref = { 0, @@ -872,6 +918,90 @@ int main(int argc, char **argv) { int sndbuf, target_sndbuf = 131072; socklen_t len; char *sockname, *ssockname; + + res = get_address(&config->broadcast, &pref, &sockname); + if(!res) exit(-1); + if(config->broadcast_from.n) { + sres = get_address(&config->broadcast_from, &prefbind, &ssockname); + if(!sres) exit(-1); + } else + sres = 0; + if((bfd = socket(res->ai_family, + res->ai_socktype, + res->ai_protocol)) < 0) + fatal(errno, "error creating broadcast socket"); + if(setsockopt(bfd, SOL_SOCKET, SO_BROADCAST, &one, sizeof one) < 0) + fatal(errno, "error setting SO_BROADCAST on broadcast socket"); + len = sizeof sndbuf; + if(getsockopt(bfd, SOL_SOCKET, SO_SNDBUF, + &sndbuf, &len) < 0) + fatal(errno, "error getting SO_SNDBUF"); + if(target_sndbuf > sndbuf) { + if(setsockopt(bfd, SOL_SOCKET, SO_SNDBUF, + &target_sndbuf, sizeof target_sndbuf) < 0) + error(errno, "error setting SO_SNDBUF to %d", target_sndbuf); + else + info("changed socket send buffer size from %d to %d", + sndbuf, target_sndbuf); + } else + info("default socket send buffer is %d", + sndbuf); + /* We might well want to set additional broadcast- or multicast-related + * options here */ + if(sres && bind(bfd, sres->ai_addr, sres->ai_addrlen) < 0) + fatal(errno, "error binding broadcast socket to %s", ssockname); + if(connect(bfd, res->ai_addr, res->ai_addrlen) < 0) + fatal(errno, "error connecting broadcast socket to %s", sockname); + /* Select an SSRC */ + gcry_randomize(&rtp_id, sizeof rtp_id, GCRY_STRONG_RANDOM); + info("selected network backend, sending to %s", sockname); + if(config->sample_format.byte_format != AO_FMT_BIG) { + info("forcing big-endian sample format"); + config->sample_format.byte_format = AO_FMT_BIG; + } +} + +/** @brief Structure of a backend */ +struct speaker_backend { + /** @brief Which backend this is + * + * @c -1 terminates the list. + */ + int backend; + + /** @brief Initialization + * + * Called once at startup. + */ + void (*init)(void); +}; + +/** @brief Selected backend */ +static const struct speaker_backend *backend; + +/** @brief Table of speaker backends */ +static const struct speaker_backend backends[] = { +#if API_ALSA + { + BACKEND_ALSA, + alsa_init + }, +#endif + { + BACKEND_COMMAND, + command_init + }, + { + BACKEND_NETWORK, + network_init + }, + { -1, 0 } +}; + +int main(int argc, char **argv) { + int n, fd, stdin_slot, alsa_slots, cmdfd_slot, bfd_slot, poke, timeout; + struct track *t; + struct speaker_message sm; #if API_ALSA int alsa_nslots = -1, err; #endif @@ -905,54 +1035,15 @@ int main(int argc, char **argv) { become_mortal(); /* make sure we're not root, whatever the config says */ if(getuid() == 0 || geteuid() == 0) fatal(0, "do not run as root"); - switch(config->speaker_backend) { - case BACKEND_ALSA: - info("selected ALSA backend"); - case BACKEND_COMMAND: - info("selected command backend"); - fork_cmd(); - break; - case BACKEND_NETWORK: - res = get_address(&config->broadcast, &pref, &sockname); - if(!res) return -1; - if(config->broadcast_from.n) { - sres = get_address(&config->broadcast_from, &prefbind, &ssockname); - if(!sres) return -1; - } else - sres = 0; - if((bfd = socket(res->ai_family, - res->ai_socktype, - res->ai_protocol)) < 0) - fatal(errno, "error creating broadcast socket"); - if(setsockopt(bfd, SOL_SOCKET, SO_BROADCAST, &one, sizeof one) < 0) - fatal(errno, "error setting SO_BROADCAST on broadcast socket"); - len = sizeof sndbuf; - if(getsockopt(bfd, SOL_SOCKET, SO_SNDBUF, - &sndbuf, &len) < 0) - fatal(errno, "error getting SO_SNDBUF"); - if(setsockopt(bfd, SOL_SOCKET, SO_SNDBUF, - &target_sndbuf, sizeof target_sndbuf) < 0) - error(errno, "error setting SO_SNDBUF to %d", target_sndbuf); - else - info("changed socket send buffer size from %d to %d", - sndbuf, target_sndbuf); - /* We might well want to set additional broadcast- or multicast-related - * options here */ - if(sres && bind(bfd, sres->ai_addr, sres->ai_addrlen) < 0) - fatal(errno, "error binding broadcast socket to %s", ssockname); - if(connect(bfd, res->ai_addr, res->ai_addrlen) < 0) - fatal(errno, "error connecting broadcast socket to %s", sockname); - /* Select an SSRC */ - gcry_randomize(&rtp_id, sizeof rtp_id, GCRY_STRONG_RANDOM); - info("selected network backend, sending to %s", sockname); - if(config->sample_format.byte_format != AO_FMT_BIG) { - info("forcing big-endian sample format"); - config->sample_format.byte_format = AO_FMT_BIG; - } - break; - default: - fatal(0, "unknown backend %d", config->speaker_backend); - } + /* identify the backend used to play */ + for(n = 0; backends[n].backend != -1; ++n) + if(backends[n].backend == config->speaker_backend) + break; + if(backends[n].backend == -1) + fatal(0, "unsupported backend %d", config->speaker_backend); + backend = &backends[n]; + /* backend-specific initialization */ + backend->init(); while(getppid() != 1) { fdno = 0; /* Always ready for commands from the main server. */ @@ -987,7 +1078,9 @@ int main(int argc, char **argv) { * config->sample_format.rate * config->sample_format.channels / 1000); +#if 0 static unsigned logit; +#endif /* If we're starting then initialize the base time */ if(!rtp_time) @@ -1001,7 +1094,7 @@ int main(int argc, char **argv) { * config->sample_format.channels) / 1000000; -#if 1 +#if 0 /* TODO remove logging guff */ if(!(logit++ & 1023)) info("rtp_time %llu target %llu difference %lld [%lld]",