This patch implements the infrastructure to load the plugin configuration from ALSA configuration file. The configuration is loaded in open() callback.
All configuration parameters are described in details in doc/aaf.txt file.
Signed-off-by: Andre Guedes andre.guedes@intel.com --- aaf/pcm_aaf.c | 131 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ doc/aaf.txt | 52 +++++++++++++++++++++++ 2 files changed, 183 insertions(+)
diff --git a/aaf/pcm_aaf.c b/aaf/pcm_aaf.c index 7890e10..32db15e 100644 --- a/aaf/pcm_aaf.c +++ b/aaf/pcm_aaf.c @@ -20,11 +20,138 @@
#include <alsa/asoundlib.h> #include <alsa/pcm_external.h> +#include <linux/if.h> +#include <linux/if_ether.h> +#include <string.h> +#include <stdint.h> + +#define NSEC_PER_USEC 1000
typedef struct { snd_pcm_ioplug_t io; + + char ifname[IFNAMSIZ]; + unsigned char addr[ETH_ALEN]; + int prio; + uint64_t streamid; + int mtt; + int t_uncertainty; + snd_pcm_uframes_t frames_per_pdu; } snd_pcm_aaf_t;
+static int aaf_load_config(snd_pcm_aaf_t *aaf, snd_config_t *conf) +{ + snd_config_iterator_t cur, next; + + snd_config_for_each(cur, next, conf) { + snd_config_t *entry = snd_config_iterator_entry(cur); + const char *id; + + if (snd_config_get_id(entry, &id) < 0) + goto err; + + if (strcmp(id, "comment") == 0 || + strcmp(id, "type") == 0 || + strcmp(id, "hint") == 0) + continue; + + if (strcmp(id, "ifname") == 0) { + const char *ifname; + + if (snd_config_get_string(entry, &ifname) < 0) + goto err; + + snprintf(aaf->ifname, sizeof(aaf->ifname), "%s", + ifname); + } else if (strcmp(id, "addr") == 0) { + const char *addr; + int n; + + if (snd_config_get_string(entry, &addr) < 0) + goto err; + + n = sscanf(addr, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx", + &aaf->addr[0], &aaf->addr[1], + &aaf->addr[2], &aaf->addr[3], + &aaf->addr[4], &aaf->addr[5]); + if (n != 6) + goto err; + } else if (strcmp(id, "prio") == 0) { + long prio; + + if (snd_config_get_integer(entry, &prio) < 0) + goto err; + + if (prio < 0) + goto err; + + aaf->prio = prio; + } else if (strcmp(id, "streamid") == 0) { + const char *streamid; + unsigned char addr[6]; + unsigned short unique_id; + int n; + + if (snd_config_get_string(entry, &streamid) < 0) + goto err; + + n = sscanf(streamid, + "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx:%hx", + &addr[0], &addr[1], &addr[2], &addr[3], + &addr[4], &addr[5], &unique_id); + if (n != 7) + goto err; + + aaf->streamid = (uint64_t) addr[0] << 56 | + (uint64_t) addr[1] << 48 | + (uint64_t) addr[2] << 40 | + (uint64_t) addr[3] << 32 | + (uint64_t) addr[4] << 24 | + (uint64_t) addr[5] << 16 | + unique_id; + } else if (strcmp(id, "mtt") == 0) { + long mtt; + + if (snd_config_get_integer(entry, &mtt) < 0) + goto err; + + if (mtt < 0) + goto err; + + aaf->mtt = mtt * NSEC_PER_USEC; + } else if (strcmp(id, "time_uncertainty") == 0) { + long t_uncertainty; + + if (snd_config_get_integer(entry, &t_uncertainty) < 0) + goto err; + + if (t_uncertainty < 0) + goto err; + + aaf->t_uncertainty = t_uncertainty * NSEC_PER_USEC; + } else if (strcmp(id, "frames_per_pdu") == 0) { + long frames_per_pdu; + + if (snd_config_get_integer(entry, &frames_per_pdu) < 0) + goto err; + + if (frames_per_pdu < 0) + goto err; + + aaf->frames_per_pdu = frames_per_pdu; + } else { + SNDERR("Invalid configuration: %s", id); + goto err; + } + } + + return 0; + +err: + SNDERR("Error loading device configuration"); + return -EINVAL; +} + static int aaf_close(snd_pcm_ioplug_t *io) { snd_pcm_aaf_t *aaf = io->private_data; @@ -70,6 +197,10 @@ SND_PCM_PLUGIN_DEFINE_FUNC(aaf) return -ENOMEM; }
+ res = aaf_load_config(aaf, conf); + if (res < 0) + goto err; + aaf->io.version = SND_PCM_IOPLUG_VERSION; aaf->io.name = "AVTP Audio Format (AAF) Plugin"; aaf->io.callback = &aaf_callback; diff --git a/doc/aaf.txt b/doc/aaf.txt index b260a26..d817249 100644 --- a/doc/aaf.txt +++ b/doc/aaf.txt @@ -16,3 +16,55 @@ The AAF plugin uses libavtp to handle AVTP packetization. Libavtp source code can be found in https://github.com/AVnu/libavtp as well as instructions to build and install it. If libavtp isn't detected by configure, the plugin isn't built. + +Plugin Configuration and Usage +------------------------------ + +The plugin parameters are passed via ALSA configuration file. They are defined +as follows: + + * ifname: Network interface used to transmit/receive AVTP packets. + + * addr: Stream destination MAC address. + + * prio: Priority used by the plugin to transmit AVTP traffic. This + option is relevant only when operating in playback mode. + + * streamid: Stream ID associated with the AAF stream transmitted or + received by the plugin. + + * mtt: Maximum Transit Time (in microseconds) as defined in AVTP spec + section 4.3.3. This option is relevant only when operating in + playback mode. + + * time_uncertainty: Maximum Time Uncertainty (in microseconds) as + defined by AVTP spec section 4.3.3. This option is relevant only when + operating in playback mode. + + * frames_per_pdu: Number of audio frames transmitted in one AVTPDU. + +The plugin provides the PCM type "aaf". Configure an AAF PCM virtual device +according to the AAF stream you want to transmit or receive. A hypothetical +configuration file is shown below: + + pcm.aaf { + type aaf + ifname eth0 + addr AA:AA:AA:AA:AA:AA + prio 3 + streamid BB:BB:BB:BB:BB:BB:0001 + mtt 2000 + time_uncertainty 125 + frames_per_pdu 6 + } + +Put the above to ~/.asoundrc (or /etc/asound.conf), and use the AAF PCM virtual +device with your ALSA apps. For example, to stream the content from a wav file +through the network, run: + + $ aplay -Daaf foo.wav + +To receive the AAF stream generated by the previous command, run the following +command in another host: + + $ arecord -Daaf