Examples: add audiotestsrc plugin example

2 files changed, 193 insertions, 1 deletions

diff --git a/examples/plugins/python/py_audiotestsrc.py b/examples/plugins/python/py_audiotestsrc.py
new file mode 100644
index 0000000..6d5ff21
--- /dev/null
+++ b/examples/plugins/python/py_audiotestsrc.py
@@ -0,0 +1,190 @@
+'''
+Element that generates a sine audio wave with the specified frequency
+
+Requires numpy
+
+Example pipeline:
+
+gst-launch-1.0 py_audiotestsrc ! autoaudiosink
+'''
+
+import gi
+
+gi.require_version('Gst', '1.0')
+gi.require_version('GstBase', '1.0')
+gi.require_version('GstAudio', '1.0')
+
+from gi.repository import Gst, GLib, GObject, GstBase, GstAudio
+
+try:
+    import numpy as np
+except ImportError:
+    Gst.error('py_audiotestsrc requires numpy')
+    raise
+
+OCAPS = Gst.Caps.from_string (
+        'audio/x-raw, format=F32LE, layout=interleaved, rate=44100, channels=2')
+
+SAMPLESPERBUFFER = 1024
+
+DEFAULT_FREQ = 440
+DEFAULT_VOLUME = 0.8
+DEFAULT_MUTE = False
+DEFAULT_IS_LIVE = False
+
+class AudioTestSrc(GstBase.BaseSrc):
+    __gstmetadata__ = ('CustomSrc','Src', \
+                      'Custom test src element', 'Mathieu Duponchelle')
+
+    __gproperties__ = {
+        "freq": (int,
+                 "Frequency",
+                 "Frequency of test signal",
+                 1,
+                 GLib.MAXINT,
+                 DEFAULT_FREQ,
+                 GObject.ParamFlags.READWRITE
+                ),
+        "volume": (float,
+                   "Volume",
+                   "Volume of test signal",
+                   0.0,
+                   1.0,
+                   DEFAULT_VOLUME,
+                   GObject.ParamFlags.READWRITE
+                  ),
+        "mute": (bool,
+                 "Mute",
+                 "Mute the test signal",
+                 DEFAULT_MUTE,
+                 GObject.ParamFlags.READWRITE
+                ),
+        "is-live": (bool,
+                 "Is live",
+                 "Whether to act as a live source",
+                 DEFAULT_IS_LIVE,
+                 GObject.ParamFlags.READWRITE
+                ),
+    }
+
+    __gsttemplates__ = Gst.PadTemplate.new("src",
+                                           Gst.PadDirection.SRC,
+                                           Gst.PadPresence.ALWAYS,
+                                           OCAPS)
+
+    def __init__(self):
+        GstBase.BaseSrc.__init__(self)
+        self.info = GstAudio.AudioInfo()
+
+        self.freq = DEFAULT_FREQ
+        self.volume = DEFAULT_VOLUME
+        self.mute = DEFAULT_MUTE
+
+        self.set_live(DEFAULT_IS_LIVE)
+        self.set_format(Gst.Format.TIME)
+
+    def do_set_caps(self, caps):
+        self.info.from_caps(caps)
+        self.set_blocksize(self.info.bpf * SAMPLESPERBUFFER)
+        return True
+
+    def do_get_property(self, prop):
+        if prop.name == 'freq':
+            return self.freq
+        elif prop.name == 'volume':
+            return self.volume
+        elif prop.name == 'mute':
+            return self.mute
+        elif prop.name == 'is-live':
+            return self.is_live
+        else:
+            raise AttributeError('unknown property %s' % prop.name)
+
+    def do_set_property(self, prop, value):
+        if prop.name == 'freq':
+            self.freq = value
+        elif prop.name == 'volume':
+            self.volume = value
+        elif prop.name == 'mute':
+            self.mute = value
+        elif prop.name == 'is-live':
+            self.set_live(value)
+        else:
+            raise AttributeError('unknown property %s' % prop.name)
+
+    def do_start (self):
+        self.next_sample = 0
+        self.next_byte = 0
+        self.next_time = 0
+        self.accumulator = 0
+        self.generate_samples_per_buffer = SAMPLESPERBUFFER
+
+        return True
+
+    def do_gst_base_src_query(self, query):
+        if query.type == Gst.QueryType.LATENCY:
+            latency = Gst.util_uint64_scale_int(self.generate_samples_per_buffer,
+                    Gst.SECOND, self.info.rate)
+            is_live = self.is_live
+            query.set_latency(is_live, latency, Gst.CLOCK_TIME_NONE)
+            res = True
+        else:
+            res = GstBase.BaseSrc.do_query(self, query)
+        return res
+
+    def do_get_times(self, buf):
+        end = 0
+        start = 0
+        if self.is_live:
+            ts = buf.pts
+            if ts != Gst.CLOCK_TIME_NONE:
+                duration = buf.duration
+                if duration != Gst.CLOCK_TIME_NONE:
+                    end = ts + duration
+                start = ts
+        else:
+            start = Gst.CLOCK_TIME_NONE
+            end = Gst.CLOCK_TIME_NONE
+
+        return start, end
+
+    def do_create(self, offset, length):
+        if length == -1:
+            samples = SAMPLESPERBUFFER
+        else:
+            samples = int(length / self.info.bpf)
+
+        self.generate_samples_per_buffer = samples
+
+        bytes_ = samples * self.info.bpf
+
+        next_sample = self.next_sample + samples
+        next_byte = self.next_byte + bytes_
+        next_time = Gst.util_uint64_scale_int(next_sample, Gst.SECOND, self.info.rate)
+
+        if not self.mute:
+            r = np.repeat(
+                    np.arange(self.accumulator, self.accumulator + samples),
+                    self.info.channels)
+            data = ((np.sin(2 * np.pi * r * self.freq / self.info.rate) * self.volume)
+                    .astype(np.float32))
+        else:
+            data = [0] * bytes_
+
+        buf = Gst.Buffer.new_wrapped(bytes(data))
+
+        buf.offset = self.next_sample
+        buf.offset_end = next_sample
+        buf.pts = self.next_time
+        buf.duration = next_time - self.next_time
+
+        self.next_time = next_time
+        self.next_sample = next_sample
+        self.next_byte = next_byte
+        self.accumulator += samples
+        self.accumulator %= self.info.rate / self.freq
+
+        return (Gst.FlowReturn.OK, buf)
+
+
+__gstelementfactory__ = ("py_audiotestsrc", Gst.Rank.NONE, AudioTestSrc)
diff --git a/examples/requirements.txt b/examples/requirements.txt
index e3962db..b0358b3 100644
--- a/examples/requirements.txt
+++ b/examples/requirements.txt
@@ -3,5 +3,7 @@ Pillow >= 5.1.0
 
 # audioplot plugin
 matplotlib >= 2.1.1
-numpy >= 1.14.5
 numpy_ringbuffer >= 0.2.1
+
+# audioplot and py_audiotestsrc plugins
+numpy >= 1.14.5