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@xxxxxxxxx>
---
aaf/pcm_aaf.c | 126 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
doc/aaf.txt | 52 ++++++++++++++++++++++++
2 files changed, 178 insertions(+)
diff --git a/aaf/pcm_aaf.c b/aaf/pcm_aaf.c
index 7890e10..4c6f031 100644
--- a/aaf/pcm_aaf.c
+++ b/aaf/pcm_aaf.c
@@ -20,11 +20,133 @@
#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 1000ULL
typedef struct {
snd_pcm_ioplug_t io;
+
+ char ifname[IFNAMSIZ];
+ uint8_t addr[ETH_ALEN];
+ int prio;
+ uint64_t streamid;
+ int mtt;
+ int t_uncertainty;
+ int frames_per_pkt;
} 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;
+ int n;
+ uint64_t buf[7];
+
+ if (snd_config_get_string(entry, &streamid) < 0)
+ goto err;
+
+ n = sscanf(streamid, "%lx:%lx:%lx:%lx:%lx:%lx:%lx",
+ &buf[0], &buf[1], &buf[2], &buf[3],
+ &buf[4], &buf[5], &buf[6]);
+ if (n != 7)
+ goto err;
+
+ aaf->streamid = buf[0] << 56 | buf[1] << 48 |
+ buf[2] << 40 | buf[3] << 32 |
+ buf[4] << 24 | buf[5] << 16 |
+ buf[6];
+ } 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_pkt") == 0) {
+ long frames_per_pkt;
+
+ if (snd_config_get_integer(entry, &frames_per_pkt) < 0)
+ goto err;
+
+ if (frames_per_pkt < 0)
+ goto err;
+
+ aaf->frames_per_pkt = frames_per_pkt;
+ } 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 +192,10 @@ 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 22144de..24ea888 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
+--------------------
+
+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_pkt: Number of audio frames transmitted in one AVTP
+ packet.
+
+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_pkt 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:
+
+ $ arecord -Daaf
--
2.14.4
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