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audiotestsrc: Improvements to the "ticks" wave
(Initially discussed in https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/issues/305) The ticks waveform can be useful for audio synchronization diagnostics and other cases where the time offset between waveforms is important. However, in its current form, it is too limited, and has problems with discontinuities, which result in severe artifacts when this waveform is output by a DAC. This patch fixes some discontinuities and considerably expand the ticks waveform's flexibility. They also introduce the notion of a "marker tick"; every Nth tick can have a different amplitude (usually one that is larger than the others). This is useful for combining frequent oscilloscope triggering with large time offset detection. For example, without marker ticks, the tick intervals must not be too small, otherwise the maximum time offset that can be unambiguously detected is quite small (for example, if the interval is 50ms, then no time offset larger than 25ms can be unambiguously recognized). If the tick intervals are too far apart, then no sudden changes can be clearly observed, since the oscilloscope is not updated quickly enough. But with marker ticks, this is not an issue: If there's for example a tick every 100 ms, then the oscilloscope can be triggered every 100 ms. And, if every 20th tick is a marker tick, then time offsets of up to 1 second can be discovered, even though the time between ticks is 100 ms. The patch also applies some minor cleanup to the audiotestsrc documentation.
This commit is contained in:
Carlos Rafael Giani
Tim-Philipp Müller
parent
a52ad2078a
commit
c656cfb170
2 changed files with 185 additions and 19 deletions
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@ -21,7 +21,51 @@
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* @title: audiotestsrc
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*
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* AudioTestSrc can be used to generate basic audio signals. It support several
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* different waveforms and allows to set the base frequency and volume.
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* different waveforms and allows to set the base frequency and volume. Some
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* waveforms might use additional properties.
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*
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* Waveform specific notes:
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*
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* <orderedlist>
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* <listitem>
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* <itemizedlist><title>Gaussian white noise</title>
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*
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* This waveform produces white (zero mean) Gaussian noise.
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* Volume sets the standard deviation of the noise in units of the range
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* of values of the sample type, e.g. volume=0.1 produces noise with a
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* standard deviation of 0.1*32767=3277 with 16-bit integer samples,
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* or 0.1*1.0=0.1 with floating-point samples.
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*
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* </itemizedlist>
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* </listitem>
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* <listitem>
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* <itemizedlist><title>Ticks</title>
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*
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* This waveform is special in that it does not produce one continuous
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* signal. Instead, it produces finite-length sine wave pulses (the "ticks").
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* It is useful for detecting time shifts between audio signal, for example
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* between RTSP audio clients that shall play synchronized. It is also useful
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* for generating a signal that feeds the trigger of an oscilloscope.
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*
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* To further help with oscilloscope triggering and time offset detection,
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* the waveform can apply a different volume to every Nth tick (this is then
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* called the "marker tick"). For instance, one could generate a tick every
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* 100ms, and make every 20th tick a marker tick (meaning that every 2 seconds
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* there is a marker tick). This is useful for detecting large time offsets
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* while still frequently triggering an oscilloscope.
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*
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* Also, a "ramp" can be applied to the begin & end of ticks. The sudden
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* start of the sine tick is a discontinuity, even if the sine wave starts
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* at 0. The* resulting artifacts can often make it more difficult to use the
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* ticks for an oscilloscope's trigger. To that end, an initial "ramp" can
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* be applied. The first few samples are modulated by a cubic function to
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* reduce the impact of the discontinuity, resulting in smaller artifacts.
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* The number of samples equals floor(samplerate / sine-wave-frequency).
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* Example: with a sample rate of 48 kHz and a sine wave frequency of 10 kHz,
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* the first 4 samples are modulated by the cubic function.
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* </itemizedlist>
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* </listitem>
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* </orderedlist>
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*
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* ## Example launch line
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* |[
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@ -30,12 +74,20 @@
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* This pipeline produces a sine with default frequency, 440 Hz, and the
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* default volume, 0.8 (relative to a maximum 1.0).
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* |[
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* gst-launch-1.0 audiotestsrc wave=2 freq=200 ! tee name=t ! queue ! audioconvert ! autoaudiosink t. ! queue ! audioconvert ! libvisual_lv_scope ! videoconvert ! autovideosink
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* gst-launch-1.0 audiotestsrc wave=2 freq=200 ! tee name=t ! queue ! audioconvert ! \
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* autoaudiosink t. ! queue ! audioconvert ! libvisual_lv_scope ! videoconvert ! autovideosink
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* ]|
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* In this example a saw wave is generated. The wave is shown using a
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* scope visualizer from libvisual, allowing you to visually verify that
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* the saw wave is correct.
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*
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* |[
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* gst-launch-1.0 audiotestsrc wave=ticks apply-tick-ramp=true tick-interval=100000000 \
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* freq=10000 volume=0.4 marker-tick-period=10 sine-periods-per-tick=20 ! autoaudiosink
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* ]| This pipeline produces a series of 10 kHz sine wave ticks. Each tick is
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* 20 sine wave periods long, ticks occur every 100 ms and have a volume of
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* 0.4. Every 10th tick is a marker tick and has the default marker tick volume
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* of 1.0. The beginning and end of the ticks are modulated with the ramp.
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*/
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#ifdef HAVE_CONFIG_H
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@ -54,14 +106,19 @@
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GST_DEBUG_CATEGORY_STATIC (audio_test_src_debug);
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#define GST_CAT_DEFAULT audio_test_src_debug
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#define DEFAULT_SAMPLES_PER_BUFFER 1024
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#define DEFAULT_WAVE GST_AUDIO_TEST_SRC_WAVE_SINE
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#define DEFAULT_FREQ 440.0
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#define DEFAULT_VOLUME 0.8
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#define DEFAULT_IS_LIVE FALSE
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#define DEFAULT_TIMESTAMP_OFFSET G_GINT64_CONSTANT (0)
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#define DEFAULT_CAN_ACTIVATE_PUSH TRUE
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#define DEFAULT_CAN_ACTIVATE_PULL FALSE
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#define DEFAULT_SAMPLES_PER_BUFFER 1024
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#define DEFAULT_WAVE GST_AUDIO_TEST_SRC_WAVE_SINE
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#define DEFAULT_FREQ 440.0
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#define DEFAULT_VOLUME 0.8
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#define DEFAULT_IS_LIVE FALSE
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#define DEFAULT_TIMESTAMP_OFFSET G_GINT64_CONSTANT (0)
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#define DEFAULT_SINE_PERIODS_PER_TICK 10
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#define DEFAULT_TIME_BETWEEN_TICKS GST_SECOND
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#define DEFAULT_MARKER_TICK_PERIOD 0
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#define DEFAULT_MARKER_TICK_VOLUME 1.0
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#define DEFAULT_APPLY_TICK_RAMP FALSE
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#define DEFAULT_CAN_ACTIVATE_PUSH TRUE
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#define DEFAULT_CAN_ACTIVATE_PULL FALSE
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enum
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{
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@ -72,6 +129,11 @@ enum
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PROP_VOLUME,
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PROP_IS_LIVE,
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PROP_TIMESTAMP_OFFSET,
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PROP_SINE_PERIODS_PER_TICK,
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PROP_TICK_INTERVAL,
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PROP_MARKER_TICK_PERIOD,
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PROP_MARKER_TICK_VOLUME,
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PROP_APPLY_TICK_RAMP,
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PROP_CAN_ACTIVATE_PUSH,
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PROP_CAN_ACTIVATE_PULL
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};
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@ -200,6 +262,32 @@ gst_audio_test_src_class_init (GstAudioTestSrcClass * klass)
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"An offset added to timestamps set on buffers (in ns)", G_MININT64,
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G_MAXINT64, DEFAULT_TIMESTAMP_OFFSET,
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G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
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g_object_class_install_property (gobject_class, PROP_SINE_PERIODS_PER_TICK,
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g_param_spec_uint ("sine-periods-per-tick", "Sine periods per tick",
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"Number of sine wave periods in one tick. Only used if wave = ticks.",
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1, G_MAXUINT, DEFAULT_SINE_PERIODS_PER_TICK,
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G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
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g_object_class_install_property (gobject_class, PROP_TICK_INTERVAL,
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g_param_spec_uint64 ("tick-interval", "Time between ticks",
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"Distance between start of current and start of next tick, in nanoseconds.",
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1, G_MAXUINT64, DEFAULT_TIME_BETWEEN_TICKS,
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G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
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g_object_class_install_property (gobject_class, PROP_MARKER_TICK_PERIOD,
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g_param_spec_uint ("marker-tick-period", "Marker tick period",
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"Make every Nth tick a marker tick (= a tick with different volume). "
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"Only used if wave = ticks. 0 = no marker ticks.",
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0, G_MAXUINT, DEFAULT_MARKER_TICK_PERIOD,
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G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
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g_object_class_install_property (gobject_class, PROP_MARKER_TICK_VOLUME,
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g_param_spec_double ("marker-tick-volume", "Marker tick volume",
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"Volume of marker ticks. Only used if wave = ticks and"
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"marker-tick-period is set to a nonzero value.",
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0.0, 1.0, DEFAULT_MARKER_TICK_VOLUME,
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G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
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g_object_class_install_property (gobject_class, PROP_APPLY_TICK_RAMP,
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g_param_spec_boolean ("apply-tick-ramp", "Apply tick ramp",
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"Apply ramp to tick samples", DEFAULT_APPLY_TICK_RAMP,
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G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
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g_object_class_install_property (gobject_class, PROP_CAN_ACTIVATE_PUSH,
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g_param_spec_boolean ("can-activate-push", "Can activate push",
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"Can activate in push mode", DEFAULT_CAN_ACTIVATE_PUSH,
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@ -244,6 +332,12 @@ gst_audio_test_src_init (GstAudioTestSrc * src)
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src->timestamp_offset = DEFAULT_TIMESTAMP_OFFSET;
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src->can_activate_pull = DEFAULT_CAN_ACTIVATE_PULL;
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src->sine_periods_per_tick = DEFAULT_SINE_PERIODS_PER_TICK;
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src->tick_interval = DEFAULT_TIME_BETWEEN_TICKS;
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src->marker_tick_period = DEFAULT_MARKER_TICK_PERIOD;
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src->marker_tick_volume = DEFAULT_MARKER_TICK_VOLUME;
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src->apply_tick_ramp = DEFAULT_APPLY_TICK_RAMP;
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src->gen = NULL;
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src->wave = DEFAULT_WAVE;
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@ -756,12 +850,12 @@ static const ProcessFunc pink_noise_funcs[] = {
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};
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static void
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gst_audio_test_src_init_sine_table (GstAudioTestSrc * src)
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gst_audio_test_src_init_sine_table (GstAudioTestSrc * src, gboolean use_volume)
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{
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gint i;
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gdouble ang = 0.0;
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gdouble step = M_PI_M2 / 1024.0;
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gdouble amp = src->volume;
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gdouble amp = use_volume ? src->volume : 1.0;
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for (i = 0; i < 1024; i++) {
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src->wave_table[i] = sin (ang) * amp;
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@ -814,14 +908,28 @@ static const ProcessFunc sine_table_funcs[] = {
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(ProcessFunc) gst_audio_test_src_create_sine_table_double
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};
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static inline gdouble
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calc_scaled_tick_volume (GstAudioTestSrc * src, gdouble scale)
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{
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gdouble vol;
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vol = ((src->marker_tick_period > 0)
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&& ((src->tick_counter % src->marker_tick_period) == 0))
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? src->marker_tick_volume : src->volume;
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return vol * scale;
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}
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#define DEFINE_TICKS(type,scale) \
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static void \
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gst_audio_test_src_create_tick_##type (GstAudioTestSrc * src, g##type * samples) \
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{ \
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gint i, c, channels, samplerate, samplemod, channel_step, sample_step; \
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gint num_nonzero_samples, num_ramp_samples, end_ramp_offset; \
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gdouble step, scl; \
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gdouble volscale; \
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g##type *ptr; \
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\
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volscale = calc_scaled_tick_volume (src, scale); \
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channels = GST_AUDIO_INFO_CHANNELS (&src->info); \
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if (GST_AUDIO_INFO_LAYOUT (&src->info) == GST_AUDIO_LAYOUT_INTERLEAVED) { \
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channel_step = 1; \
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@ -832,18 +940,35 @@ gst_audio_test_src_create_tick_##type (GstAudioTestSrc * src, g##type * samples)
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} \
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samplerate = GST_AUDIO_INFO_RATE (&src->info); \
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step = M_PI_M2 * src->freq / samplerate; \
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num_nonzero_samples = samplerate * src->sine_periods_per_tick / src->freq; \
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scl = 1024.0 / M_PI_M2; \
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num_ramp_samples = src->apply_tick_ramp ? (samplerate / src->freq) : 0; \
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end_ramp_offset = num_nonzero_samples - num_ramp_samples; \
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\
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for (i = 0; i < src->generate_samples_per_buffer; i++) { \
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samplemod = (src->next_sample + i) % samplerate; \
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samplemod = (src->next_sample + i)%src->samples_between_ticks; \
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\
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ptr = samples; \
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if (samplemod == 0) { \
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src->accumulator = 0; \
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} else if (samplemod < 1600) { \
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src->tick_counter++; \
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volscale = calc_scaled_tick_volume (src, scale); \
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} else if (samplemod < num_nonzero_samples) { \
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gdouble ramp; \
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if (num_ramp_samples > 0) { \
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ramp = \
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(samplemod < num_ramp_samples) ? (((gdouble)samplemod) / num_ramp_samples) : \
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(samplemod >= end_ramp_offset) ? (((gdouble)(num_nonzero_samples - samplemod)) / num_ramp_samples) \
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: 1.0; \
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if (ramp > 1.0) \
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ramp = 1.0; \
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ramp *= ramp * ramp; \
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} else \
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ramp = 1.0; \
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\
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for (c = 0; c < channels; ++c) { \
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*ptr = \
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(g##type) scale * src->wave_table[(gint) (src->accumulator * scl)]; \
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(g##type) volscale * ramp * src->wave_table[(gint) (src->accumulator * scl)]; \
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ptr += channel_step; \
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} \
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} else { \
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@ -1143,12 +1268,15 @@ gst_audio_test_src_change_wave (GstAudioTestSrc * src)
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src->process = pink_noise_funcs[idx];
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break;
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case GST_AUDIO_TEST_SRC_WAVE_SINE_TAB:
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gst_audio_test_src_init_sine_table (src);
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gst_audio_test_src_init_sine_table (src, TRUE);
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src->process = sine_table_funcs[idx];
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break;
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case GST_AUDIO_TEST_SRC_WAVE_TICKS:
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gst_audio_test_src_init_sine_table (src);
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gst_audio_test_src_init_sine_table (src, FALSE);
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src->process = tick_funcs[idx];
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src->samples_between_ticks =
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gst_util_uint64_scale_int (src->tick_interval,
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GST_AUDIO_INFO_RATE (&(src->info)), GST_SECOND);
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break;
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case GST_AUDIO_TEST_SRC_WAVE_GAUSSIAN_WHITE_NOISE:
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if (!(src->gen))
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@ -1188,7 +1316,7 @@ gst_audio_test_src_change_volume (GstAudioTestSrc * src)
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{
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switch (src->wave) {
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case GST_AUDIO_TEST_SRC_WAVE_SINE_TAB:
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gst_audio_test_src_init_sine_table (src);
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gst_audio_test_src_init_sine_table (src, TRUE);
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break;
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default:
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break;
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@ -1230,6 +1358,7 @@ gst_audio_test_src_start (GstBaseSrc * basesrc)
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src->eos_reached = FALSE;
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src->tags_pushed = FALSE;
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src->accumulator = 0;
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src->tick_counter = 0;
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return TRUE;
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}
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@ -1474,6 +1603,21 @@ gst_audio_test_src_set_property (GObject * object, guint prop_id,
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case PROP_TIMESTAMP_OFFSET:
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src->timestamp_offset = g_value_get_int64 (value);
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break;
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case PROP_SINE_PERIODS_PER_TICK:
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src->sine_periods_per_tick = g_value_get_uint (value);
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break;
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case PROP_TICK_INTERVAL:
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src->tick_interval = g_value_get_uint64 (value);
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break;
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case PROP_MARKER_TICK_PERIOD:
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src->marker_tick_period = g_value_get_uint (value);
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break;
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case PROP_MARKER_TICK_VOLUME:
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src->marker_tick_volume = g_value_get_double (value);
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break;
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case PROP_APPLY_TICK_RAMP:
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src->apply_tick_ramp = g_value_get_boolean (value);
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break;
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case PROP_CAN_ACTIVATE_PUSH:
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GST_BASE_SRC (src)->can_activate_push = g_value_get_boolean (value);
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break;
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@ -1511,6 +1655,21 @@ gst_audio_test_src_get_property (GObject * object, guint prop_id,
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case PROP_TIMESTAMP_OFFSET:
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g_value_set_int64 (value, src->timestamp_offset);
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break;
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case PROP_SINE_PERIODS_PER_TICK:
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g_value_set_uint (value, src->sine_periods_per_tick);
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break;
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case PROP_TICK_INTERVAL:
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g_value_set_uint64 (value, src->tick_interval);
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break;
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case PROP_MARKER_TICK_PERIOD:
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g_value_set_uint (value, src->marker_tick_period);
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break;
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case PROP_MARKER_TICK_VOLUME:
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g_value_set_double (value, src->marker_tick_volume);
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break;
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case PROP_APPLY_TICK_RAMP:
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g_value_set_boolean (value, src->apply_tick_ramp);
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break;
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case PROP_CAN_ACTIVATE_PUSH:
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g_value_set_boolean (value, GST_BASE_SRC (src)->can_activate_push);
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break;
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@ -51,7 +51,7 @@ G_BEGIN_DECLS
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* @GST_AUDIO_TEST_SRC_WAVE_PINK_NOISE: pink noise
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* @GST_AUDIO_TEST_SRC_WAVE_SINE_TAB: sine wave using a table
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* @GST_AUDIO_TEST_SRC_WAVE_TICKS: periodic ticks
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* @GST_AUDIO_TEST_SRC_WAVE_GAUSSIAN_WHITE_NOISE: white (zero mean) Gaussian noise; volume sets the standard deviation of the noise in units of the range of values of the sample type, e.g. volume=0.1 produces noise with a standard deviation of 0.1*32767=3277 with 16-bit integer samples, or 0.1*1.0=0.1 with floating-point samples.
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* @GST_AUDIO_TEST_SRC_WAVE_GAUSSIAN_WHITE_NOISE: white (zero mean) Gaussian noise
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* @GST_AUDIO_TEST_SRC_WAVE_RED_NOISE: red (brownian) noise
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* @GST_AUDIO_TEST_SRC_WAVE_BLUE_NOISE: spectraly inverted pink noise
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* @GST_AUDIO_TEST_SRC_WAVE_VIOLET_NOISE: spectraly inverted red (brownian) noise
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@ -137,6 +137,13 @@ struct _GstAudioTestSrc {
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GstPinkNoise pink;
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GstRedNoise red;
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gdouble wave_table[1024];
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guint sine_periods_per_tick;
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guint64 tick_interval;
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guint marker_tick_period;
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gdouble marker_tick_volume;
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gboolean apply_tick_ramp;
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guint samples_between_ticks;
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guint tick_counter;
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||||
};
|
||||
|
||||
struct _GstAudioTestSrcClass {
|
||||
|
|
|
|||
Loading…
Reference in a new issue