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-rw-r--r--binding/radio_output_gstreamer.c218
1 files changed, 218 insertions, 0 deletions
diff --git a/binding/radio_output_gstreamer.c b/binding/radio_output_gstreamer.c
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+++ b/binding/radio_output_gstreamer.c
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+/*
+ * Copyright (C) 2018 Konsulko Group
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <errno.h>
+#include <gst/gst.h>
+
+#include "radio_output.h"
+#include "rtl_fm.h"
+
+// Output buffer
+static unsigned int extra;
+static int16_t extra_buf[1];
+static unsigned char *output_buf;
+
+// GStreamer state
+static GstElement *pipeline, *appsrc;
+static bool running;
+
+int radio_output_open()
+{
+ unsigned int rate = 24000;
+ GstElement *queue, *convert, *sink, *resample;
+ char *p;
+
+ if(pipeline)
+ return 0;
+
+ // Initialize GStreamer
+#ifdef DEBUG
+ unsigned int argc = 2;
+ char **argv = malloc(2 * sizeof(char*));
+ argv[0] = strdup("test");
+ argv[1] = strdup("--gst-debug-level=5");
+ gst_init(&argc, &argv);
+#else
+ gst_init(NULL, NULL);
+#endif
+
+ // Setup pipeline
+ // NOTE: With our use of the simple buffer pushing mode, there seems to
+ // be no need for a mainloop, so currently not instantiating one.
+ pipeline = gst_pipeline_new("pipeline");
+ appsrc = gst_element_factory_make("appsrc", "source");
+ queue = gst_element_factory_make("queue", "queue");
+ convert = gst_element_factory_make("audioconvert", "convert");
+ resample = gst_element_factory_make("audioresample", "resample");
+ sink = gst_element_factory_make("alsasink", "sink");
+ if(!(pipeline && appsrc && queue && convert && resample && sink)) {
+ fprintf(stderr, "pipeline element construction failed!\n");
+ }
+ g_object_set(G_OBJECT(appsrc), "caps",
+ gst_caps_new_simple("audio/x-raw",
+ "format", G_TYPE_STRING, "S16LE",
+ "rate", G_TYPE_INT, rate,
+ "channels", G_TYPE_INT, 2,
+ "layout", G_TYPE_STRING, "interleaved",
+ "channel-mask", G_TYPE_UINT64, 3,
+ NULL), NULL);
+
+ if((p = getenv("RADIO_OUTPUT"))) {
+ fprintf(stderr, "Using output device %s\n", p);
+ g_object_set(sink, "device", p, NULL);
+ }
+ gst_bin_add_many(GST_BIN(pipeline), appsrc, queue, convert, resample, sink, NULL);
+ gst_element_link_many(appsrc, queue, convert, resample, sink, NULL);
+ //gst_bin_add_many(GST_BIN(pipeline), appsrc, convert, resample, sink, NULL);
+ //gst_element_link_many(appsrc, convert, resample, sink, NULL);
+
+ // Set up appsrc
+ // NOTE: Radio seems like it matches the use case the "is-live" property
+ // is for, but setting it seems to require a lot more work with
+ // respect to latency settings to make the pipeline work smoothly.
+ // For now, leave it unset since the result seems to work
+ // reasonably well.
+ g_object_set(G_OBJECT(appsrc),
+ "stream-type", 0,
+ "format", GST_FORMAT_TIME,
+ NULL);
+
+ // Start pipeline in paused state
+ gst_element_set_state(pipeline, GST_STATE_PAUSED);
+
+ // Set up output buffer
+ extra = 0;
+ output_buf = malloc(sizeof(unsigned char) * RTL_FM_MAXIMUM_BUF_LENGTH);
+
+ return 0;
+}
+
+int radio_output_start(void)
+{
+ int rc = 0;
+
+ if(!pipeline) {
+ rc = radio_output_open();
+ if(rc)
+ return rc;
+ }
+
+ // Start pipeline
+ running = true;
+ gst_element_set_state(pipeline, GST_STATE_PLAYING);
+
+ return rc;
+}
+
+void radio_output_stop(void)
+{
+ GstEvent *event;
+
+ if(pipeline && running) {
+ // Stop pipeline
+ running = false;
+ gst_element_set_state(pipeline, GST_STATE_PAUSED);
+
+ // Flush pipeline
+ // This seems required to avoid stutters on starts after a stop
+ event = gst_event_new_flush_start();
+ gst_element_send_event(GST_ELEMENT(pipeline), event);
+ event = gst_event_new_flush_stop(TRUE);
+ gst_element_send_event(GST_ELEMENT(pipeline), event);
+ }
+}
+
+void radio_output_suspend(int state)
+{
+ // Placeholder
+}
+
+void radio_output_close(void)
+{
+ radio_output_stop();
+
+ if(pipeline) {
+ // Tear down pipeline
+ gst_element_set_state(pipeline, GST_STATE_NULL);
+ gst_object_unref(GST_OBJECT(pipeline));
+ pipeline = NULL;
+ running = false;
+ }
+
+ free(output_buf);
+ output_buf = NULL;
+}
+
+int radio_output_write(void *buf, int len)
+{
+ int rc = -EINVAL;
+ size_t n = len;
+ int samples = len / 2;
+ unsigned char *p;
+ GstBuffer *buffer;
+ GstFlowReturn ret;
+
+ if(!(pipeline && buf)) {
+ return rc;
+ }
+
+ // Don't bother pushing samples if output hasn't started
+ if(!running)
+ return 0;
+
+ /*
+ * Handle the rtl_fm code giving us an odd number of samples.
+ * This extra buffer copying approach is not particularly efficient,
+ * but works for now. It looks feasible to hack in something in the
+ * demod and output thread routines in rtl_fm.c to handle it there
+ * if more performance is required.
+ */
+ p = output_buf;
+ if(extra) {
+ memcpy(output_buf, extra_buf, sizeof(int16_t));
+ if((extra + samples) % 2) {
+ // We still have an extra sample, n remains the same, store the extra
+ memcpy(output_buf + sizeof(int16_t), buf, n - 2);
+ memcpy(extra_buf, ((unsigned char*) buf) + n - 2, sizeof(int16_t));
+ } else {
+ // We have an even number of samples, no extra
+ memcpy(output_buf + sizeof(int16_t), buf, n);
+ n += 2;
+ extra = 0;
+ }
+ } else if(samples % 2) {
+ // We have an extra sample, store it, and decrease n
+ n -= 2;
+ memcpy(output_buf + sizeof(int16_t), buf, n);
+ memcpy(extra_buf, ((unsigned char*) buf) + n, sizeof(int16_t));
+ extra = 1;
+ } else {
+ p = buf;
+ }
+
+ // Push buffer into pipeline
+ buffer = gst_buffer_new_allocate(NULL, n, NULL);
+ gst_buffer_fill(buffer, 0, p, n);
+ g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
+ gst_buffer_unref(buffer);
+ rc = n;
+
+ return rc;
+}