[alsa-devel] [PATCH v2 - AAF PCM plugin 2/7] aaf: Load configuration parameters
Andre Guedes
andre.guedes at intel.com
Thu Oct 25 03:11:11 CEST 2018
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 at intel.com>
---
aaf/pcm_aaf.c | 131 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
configure.ac | 1 +
doc/aaf.txt | 33 ++++++++++++++-
3 files changed, 164 insertions(+), 1 deletion(-)
diff --git a/aaf/pcm_aaf.c b/aaf/pcm_aaf.c
index 31d8759..c9d4b70 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_ether.h>
+#include <net/if.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)
{
free(io->private_data);
@@ -64,6 +191,10 @@ 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/configure.ac b/configure.ac
index db36f03..eadaed6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -181,6 +181,7 @@ AC_ARG_ENABLE([aaf],
if test "x$enable_aaf" != "xno"; then
PKG_CHECK_MODULES(AVTP, avtp >= 0.1, [HAVE_AAF=yes], [HAVE_AAF=no])
+ AC_CHECK_HEADERS([linux/if_ether.h], [], [HAVE_AAF=no])
fi
AM_CONDITIONAL(HAVE_AAF, test x$HAVE_AAF = xyes)
diff --git a/doc/aaf.txt b/doc/aaf.txt
index b260a26..afc794b 100644
--- a/doc/aaf.txt
+++ b/doc/aaf.txt
@@ -14,5 +14,36 @@ Plugin Dependencies
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
+build and install it.
+
+The plugin also depends on some kernel API headers such as linux/if_ether.h so
+make sure you have them installed in your system.
+
+If libavtp or the kernel headers aren'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_pdu: Number of audio frames transmitted in one AVTPDU.
--
2.14.4
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