--- /dev/null
+/* GStreamer
+ *
+ * gst-aseq-appsrc: a GStreamer appsrc for the ALSA MIDI sequencer API
+ *
+ * Copyright (C) 2014 Antonio Ospite <ao2@ao2.it>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+/* Code _heavily_ inspired to aseqdump and amidicat:
+ * http://git.alsa-project.org/?p=alsa-utils.git;a=tree;f=seq/aseqdump
+ * http://krellan.com/amidicat/
+ */
+
+#include <gst/gst.h>
+#include <gst/app/gstappsrc.h>
+
+#include <string.h>
+#include <sys/poll.h>
+#include <alsa/asoundlib.h>
+#include <glib-unix.h>
+
+#define DEFAULT_BUFSIZE 65536
+#define DEFAULT_CLIENT_NAME "gst-aseq-appsrc"
+#define DEFAULT_TICK_PERIOD_MS 10
+#define DEFAULT_POLL_TIMEOUT_MS (DEFAULT_TICK_PERIOD_MS / 2)
+
+GST_DEBUG_CATEGORY (mysrc_debug);
+#define GST_CAT_DEFAULT mysrc_debug
+
+typedef struct _App App;
+
+struct _App
+{
+ GstElement *pipeline;
+ GstElement *appsrc;
+
+ GMainLoop *loop;
+
+ snd_seq_t *seq;
+ int port_count;
+ snd_seq_addr_t *ports;
+ snd_midi_event_t *parser;
+ unsigned char *buffer;
+
+ struct pollfd *pfds;
+ int npfds;
+
+ guint64 tick;
+};
+
+App s_app;
+
+static int
+init_seq (App * app)
+{
+ int ret;
+
+ ret = snd_seq_open (&app->seq, "default", SND_SEQ_OPEN_DUPLEX, 0);
+ if (ret < 0) {
+ GST_ERROR ("Cannot open sequencer - %s", snd_strerror (ret));
+ goto error;
+ }
+
+ ret = snd_seq_set_client_name (app->seq, DEFAULT_CLIENT_NAME);
+ if (ret < 0) {
+ GST_ERROR ("Cannot set client name - %s", snd_strerror (ret));
+ goto error_seq_close;
+ }
+
+ return 0;
+
+error_seq_close:
+ snd_seq_close (app->seq);
+error:
+ return ret;
+}
+
+/* parses one or more port addresses from the string */
+static int
+parse_ports (const char *arg, App * app)
+{
+ char *buf, *s, *port_name;
+ int ret;
+
+ GST_DEBUG ("ports: %s", arg);
+
+ /* make a copy of the string because we're going to modify it */
+ buf = strdup (arg);
+ if (!buf) {
+ GST_ERROR ("Out of memory");
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ for (port_name = s = buf; s; port_name = s + 1) {
+ /* Assume that ports are separated by commas. We don't use
+ * spaces because those are valid in client names. */
+ s = strchr (port_name, ',');
+ if (s)
+ *s = '\0';
+
+ app->port_count++;
+ app->ports =
+ realloc (app->ports, app->port_count * sizeof (snd_seq_addr_t));
+ if (!app->ports) {
+ GST_ERROR ("Out of memory");
+ ret = -ENOMEM;
+ goto out_free_buf;
+ }
+
+ ret =
+ snd_seq_parse_address (app->seq, &app->ports[app->port_count - 1],
+ port_name);
+ if (ret < 0) {
+ GST_ERROR ("Invalid port %s - %s", port_name, snd_strerror (ret));
+ goto error_free_ports;
+ }
+ }
+
+ goto out_free_buf;
+
+error_free_ports:
+ free (app->ports);
+out_free_buf:
+ free (buf);
+out:
+ return ret;
+}
+
+static int
+create_port (App * app)
+{
+ int ret;
+
+ ret = snd_seq_create_simple_port (app->seq, DEFAULT_CLIENT_NAME,
+ SND_SEQ_PORT_CAP_WRITE |
+ SND_SEQ_PORT_CAP_SUBS_WRITE,
+ SND_SEQ_PORT_TYPE_MIDI_GENERIC | SND_SEQ_PORT_TYPE_APPLICATION);
+ if (ret < 0)
+ GST_ERROR ("Cannot create port - %s", snd_strerror (ret));
+
+ return ret;
+}
+
+static void
+connect_ports (App * app)
+{
+ int i;
+ int ret;
+
+ for (i = 0; i < app->port_count; ++i) {
+ ret =
+ snd_seq_connect_from (app->seq, 0, app->ports[i].client,
+ app->ports[i].port);
+ if (ret < 0)
+ /* warning */
+ GST_WARNING ("Cannot connect from port %d:%d - %s",
+ app->ports[i].client, app->ports[i].port, snd_strerror (ret));
+ }
+}
+
+static void
+push_buffer (App * app, gpointer data, guint size)
+{
+ GstBuffer *buffer;
+ GstClockTime time;
+ int ret;
+ gpointer local_data;
+
+ /* read the next chunk */
+ buffer = gst_buffer_new ();
+
+ time = app->tick * DEFAULT_TICK_PERIOD_MS * GST_MSECOND;
+
+ GST_BUFFER_DTS (buffer) = time;
+ GST_BUFFER_PTS (buffer) = time;
+ GST_BUFFER_OFFSET (buffer) = time;
+ GST_BUFFER_DURATION (buffer) = DEFAULT_TICK_PERIOD_MS * GST_MSECOND;
+
+ local_data = g_malloc (size);
+ memcpy (local_data, data, size);
+
+ gst_buffer_append_memory (buffer,
+ gst_memory_new_wrapped (0, local_data, size, 0, size, local_data,
+ g_free));
+
+ GST_DEBUG ("feed buffer %p, tick %" G_GUINT64_FORMAT " size: %u",
+ (gpointer) buffer, app->tick, size);
+ g_signal_emit_by_name (app->appsrc, "push-buffer", buffer, &ret);
+ gst_buffer_unref (buffer);
+
+ app->tick += 1;
+}
+
+static void
+push_tick_buffer (App * app)
+{
+ app->buffer[0] = 0xf9;
+ push_buffer (app, app->buffer, 1);
+}
+
+/* This method is called by the need-data signal callback, we feed data into the
+ * appsrc.
+ */
+static void
+feed_data (GstElement * appsrc, guint size, App * app)
+{
+ long size_ev = 0;
+ int err;
+ int ret;
+
+ snd_seq_poll_descriptors (app->seq, app->pfds, app->npfds, POLLIN);
+ ret = poll (app->pfds, app->npfds, DEFAULT_POLL_TIMEOUT_MS);
+ if (ret < 0) {
+ GST_ERROR ("ERROR in poll: %s", strerror (errno));
+ } else if (ret == 0) {
+ push_tick_buffer (app);
+ } else {
+ do {
+ snd_seq_event_t *event;
+ err = snd_seq_event_input (app->seq, &event);
+ if (err < 0)
+ break;
+ if (event) {
+ size_ev =
+ snd_midi_event_decode (app->parser, app->buffer, DEFAULT_BUFSIZE,
+ event);
+ if (size_ev < 0) {
+ /* ENOENT indicates an event that is not a MIDI message, silently skip it */
+ if (-ENOENT == size_ev) {
+ GST_WARNING ("Warning: Received non-MIDI message");
+ push_tick_buffer (app);
+ } else {
+ GST_ERROR ("Error decoding event from ALSA to output: %s",
+ strerror (-size_ev));
+ break;
+ }
+ } else {
+ push_buffer (app, app->buffer, size_ev);
+ }
+ }
+ } while (err > 0);
+ }
+
+ return;
+}
+
+/* this callback is called when pipeline has constructed a source object to read
+ * from. Since we provided the appsrc:// uri to pipeline, this will be the
+ * appsrc that we must handle. We set up a signals to push data into appsrc. */
+static void
+found_source (GObject * object, GObject * orig, GParamSpec * pspec, App * app)
+{
+ /* get a handle to the appsrc */
+ g_object_get (orig, pspec->name, &app->appsrc, NULL);
+
+ GST_DEBUG ("got appsrc %p", (gpointer) app->appsrc);
+
+ /* configure the appsrc, we will push a buffer to appsrc when it needs more
+ * data */
+ g_signal_connect (app->appsrc, "need-data", G_CALLBACK (feed_data), app);
+}
+
+static gboolean
+bus_message (GstBus * bus, GstMessage * message, App * app)
+{
+ GST_DEBUG ("got message %s",
+ gst_message_type_get_name (GST_MESSAGE_TYPE (message)));
+
+ switch (GST_MESSAGE_TYPE (message)) {
+ case GST_MESSAGE_ERROR:
+ {
+ GError *error = NULL;
+ gchar *dbg_info = NULL;
+
+ gst_message_parse_error (message, &error, &dbg_info);
+ g_printerr ("ERROR from element %s: %s",
+ GST_OBJECT_NAME (message->src), error->message);
+ g_printerr ("Debugging info: %s", (dbg_info) ? dbg_info : "none");
+ g_error_free (error);
+ g_free (dbg_info);
+ g_main_loop_quit (app->loop);
+ break;
+ }
+ case GST_MESSAGE_EOS:
+ g_main_loop_quit (app->loop);
+ break;
+ default:
+ break;
+ }
+ return TRUE;
+}
+
+static int
+app_init (App * app, char *ports)
+{
+ int ret;
+
+ app->tick = 0;
+
+ ret = init_seq (app);
+ if (ret < 0)
+ goto err;
+
+ if (ports) {
+ ret = parse_ports (ports, app);
+ if (ret < 0)
+ goto err_seq_close;
+ }
+
+ ret = create_port (app);
+ if (ret < 0)
+ goto err_free_ports;
+
+ connect_ports (app);
+
+ ret = snd_seq_nonblock (app->seq, 1);
+ if (ret < 0) {
+ GST_ERROR ("Cannot set nonblock mode - %s", snd_strerror (ret));
+ goto err_free_ports;
+ }
+
+ snd_midi_event_new (DEFAULT_BUFSIZE, &app->parser);
+ snd_midi_event_init (app->parser);
+ snd_midi_event_reset_decode (app->parser);
+
+ snd_midi_event_no_status (app->parser, 1);
+
+ app->buffer = malloc (DEFAULT_BUFSIZE);
+ if (app->buffer == NULL) {
+ ret = -ENOMEM;
+ goto err_free_parser;
+ }
+
+ app->npfds = snd_seq_poll_descriptors_count (app->seq, POLLIN);
+ app->pfds = alloca (sizeof (*app->pfds) * app->npfds);
+ if (app->pfds == NULL) {
+ ret = -ENOMEM;
+ goto err_free_buffer;
+ }
+
+ return 0;
+
+err_free_buffer:
+ free (app->buffer);
+err_free_parser:
+ snd_midi_event_free (app->parser);
+err_free_ports:
+ free (app->ports);
+err_seq_close:
+ snd_seq_close (app->seq);
+err:
+ return ret;
+}
+
+static void
+app_finalize (App * app)
+{
+ /* free the resources */
+ free (app->buffer);
+ free (app->ports);
+ snd_midi_event_free (app->parser);
+ snd_seq_close (app->seq);
+}
+
+static gboolean
+on_sigint (gpointer user_data)
+{
+ GMainLoop *loop = (GMainLoop *) user_data;
+ g_message ("Caught SIGINT. Initiating shutdown.");
+ g_main_loop_quit (loop);
+ return FALSE;
+}
+
+int
+main (int argc, char *argv[])
+{
+ App *app = &s_app;
+ GstBus *bus;
+ GstCaps *caps;
+ int ret;
+
+ GOptionContext *ctx;
+ GError *err = NULL;
+ gchar *ports = NULL;
+ GOptionEntry options[] = {
+ {"ports", 'p', 0, G_OPTION_ARG_STRING, &ports,
+ "Comma separated list of sequencer ports", "client:port,..."},
+ {NULL}
+ };
+
+ ctx = g_option_context_new (NULL);
+ g_option_context_add_main_entries (ctx, options, NULL);
+ g_option_context_add_group (ctx, gst_init_get_option_group ());
+ if (!g_option_context_parse (ctx, &argc, &argv, &err)) {
+ if (err)
+ g_printerr ("Error initializing: %s\n", GST_STR_NULL (err->message));
+ else
+ g_printerr ("Error initializing: Unknown error!\n");
+ exit (1);
+ }
+ g_option_context_free (ctx);
+
+ gst_init (&argc, &argv);
+
+ GST_DEBUG_CATEGORY_INIT (mysrc_debug, "mysrc", 0,
+ "ALSA MIDI sequencer appsrc pipeline");
+
+ ret = app_init (app, ports);
+ if (ret < 0)
+ return ret;
+ free (ports);
+
+ if (app->port_count > 0)
+ printf ("Waiting for data.\n");
+ else
+ printf ("Waiting for data at port %d:0.\n", snd_seq_client_id (app->seq));
+
+ /* create a mainloop to get messages */
+ app->loop = g_main_loop_new (NULL, FALSE);
+
+ app->pipeline =
+ gst_parse_launch
+ ("appsrc name=mysource ! fluiddec ! audioconvert ! autoaudiosink", NULL);
+ g_assert (app->pipeline);
+
+ bus = gst_pipeline_get_bus (GST_PIPELINE (app->pipeline));
+ g_assert (bus);
+
+ /* add watch for messages */
+ gst_bus_add_watch (bus, (GstBusFunc) bus_message, app);
+
+ /* get the appsrc */
+ app->appsrc = gst_bin_get_by_name (GST_BIN (app->pipeline), "mysource");
+ g_assert (app->appsrc);
+ g_assert (GST_IS_APP_SRC (app->appsrc));
+ g_signal_connect (app->appsrc, "need-data", G_CALLBACK (feed_data), app);
+
+ g_object_set (app->appsrc, "format", GST_FORMAT_TIME, NULL);
+ g_object_set (app->appsrc, "is-live", TRUE, NULL);
+
+ /* set the caps on the source */
+ caps = gst_caps_new_simple ("audio/x-midi-event", NULL, NULL);
+ gst_app_src_set_caps (GST_APP_SRC (app->appsrc), caps);
+ gst_caps_unref (caps);
+
+ /* get notification when the source is created so that we get a handle to it
+ * and can configure it */
+ g_signal_connect (app->pipeline, "deep-notify::source",
+ (GCallback) found_source, app);
+
+ /* go to playing and wait in a mainloop. */
+ gst_element_set_state (app->pipeline, GST_STATE_PLAYING);
+
+ /* this mainloop is stopped when we receive an error or EOS, or on SIGINT */
+ g_unix_signal_add (SIGINT, on_sigint, app->loop);
+ g_main_loop_run (app->loop);
+
+ g_main_loop_unref (app->loop);
+
+ GST_DEBUG ("stopping");
+
+ gst_element_set_state (app->pipeline, GST_STATE_NULL);
+
+ gst_object_unref (app->appsrc);
+
+ gst_object_unref (bus);
+
+ gst_object_unref (app->pipeline);
+
+ app_finalize (app);
+
+ return 0;
+}
projects / gst-aseq-appsrc.git / commitdiff