static void gst_audio_fx_base_fir_filter_dispose (GObject * object) { GstAudioFXBaseFIRFilter *self = GST_AUDIO_FX_BASE_FIR_FILTER (object); g_free (self->buffer); self->buffer = NULL; self->buffer_length = 0; g_free (self->kernel); self->kernel = NULL; gst_fft_f64_free (self->fft); self->fft = NULL; gst_fft_f64_free (self->ifft); self->ifft = NULL; g_free (self->frequency_response); self->frequency_response = NULL; g_free (self->fft_buffer); self->fft_buffer = NULL; G_OBJECT_CLASS (parent_class)->dispose (object); }
static void gst_audio_fx_base_fir_filter_finalize (GObject * object) { GstAudioFXBaseFIRFilter *self = GST_AUDIO_FX_BASE_FIR_FILTER (object); g_free (self->buffer); g_free (self->kernel); gst_fft_f64_free (self->fft); gst_fft_f64_free (self->ifft); g_free (self->frequency_response); g_free (self->fft_buffer); g_mutex_clear (&self->lock); G_OBJECT_CLASS (parent_class)->finalize (object); }
static void on_rate_changed (GstElement * element, gint rate, gpointer user_data) { GValueArray *va; GValue v = { 0, }; GstFFTF64 *fft; GstFFTF64Complex frequency_response[17]; gdouble tmp[32]; gdouble filter_kernel[32]; guint i; /* Create the frequency response: zero outside * a small frequency band */ for (i = 0; i < 17; i++) { if (i < 5 || i > 11) frequency_response[i].r = 0.0; else frequency_response[i].r = 1.0; frequency_response[i].i = 0.0; } /* Calculate the inverse FT of the frequency response */ fft = gst_fft_f64_new (32, TRUE); gst_fft_f64_inverse_fft (fft, frequency_response, tmp); gst_fft_f64_free (fft); /* Shift the inverse FT of the frequency response by 16, * i.e. the half of the kernel length to get the * impulse response. See http://www.dspguide.com/ch17/1.htm * for more information. */ for (i = 0; i < 32; i++) filter_kernel[i] = tmp[(i + 16) % 32]; /* Apply the hamming window to the impulse response to get * a better result than given from the rectangular window */ for (i = 0; i < 32; i++) filter_kernel[i] *= (0.54 - 0.46 * cos (2 * G_PI * i / 32)); va = g_value_array_new (1); g_value_init (&v, G_TYPE_DOUBLE); for (i = 0; i < 32; i++) { g_value_set_double (&v, filter_kernel[i]); g_value_array_append (va, &v); g_value_reset (&v); } g_object_set (G_OBJECT (element), "kernel", va, NULL); /* Latency is 1/2 of the kernel length for this method of * calculating a filter kernel from the frequency response */ g_object_set (G_OBJECT (element), "latency", (gint64) (32 / 2), NULL); g_value_array_free (va); }
/* Element class */ static void gst_audio_fx_base_fir_filter_calculate_frequency_response (GstAudioFXBaseFIRFilter * self) { gst_fft_f64_free (self->fft); self->fft = NULL; gst_fft_f64_free (self->ifft); self->ifft = NULL; g_free (self->frequency_response); self->frequency_response_length = 0; g_free (self->fft_buffer); self->fft_buffer = NULL; if (self->kernel && self->kernel_length >= FFT_THRESHOLD && !self->low_latency) { guint block_length, i; gdouble *kernel_tmp, *kernel = self->kernel; /* We process 4 * kernel_length samples per pass in FFT mode */ block_length = 4 * self->kernel_length; block_length = gst_fft_next_fast_length (block_length); self->block_length = block_length; kernel_tmp = g_new0 (gdouble, block_length); memcpy (kernel_tmp, kernel, self->kernel_length * sizeof (gdouble)); self->fft = gst_fft_f64_new (block_length, FALSE); self->ifft = gst_fft_f64_new (block_length, TRUE); self->frequency_response_length = block_length / 2 + 1; self->frequency_response = g_new (GstFFTF64Complex, self->frequency_response_length); gst_fft_f64_fft (self->fft, kernel_tmp, self->frequency_response); g_free (kernel_tmp); /* Normalize to make sure IFFT(FFT(x)) == x */ for (i = 0; i < self->frequency_response_length; i++) { self->frequency_response[i].r /= block_length; self->frequency_response[i].i /= block_length; } } }