1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
|
/*
* 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;
}
|
