自学教程：C++ GST_BASE_TRANSFORM函数代码示例

static voidgst_cv_laplace_init (GstCvLaplace * filter){    filter->aperture_size = DEFAULT_APERTURE_SIZE;    gst_base_transform_set_in_place (GST_BASE_TRANSFORM (filter), FALSE);}

static voidgst_alpha_color_init (GstAlphaColor * alpha){  GstBaseTransform *btrans = GST_BASE_TRANSFORM (alpha);  gst_base_transform_set_in_place (btrans, TRUE);}

voidgst_opencv_video_filter_set_in_place (GstOpencvVideoFilter * transform,    gboolean ip){  transform->in_place = ip;  gst_base_transform_set_in_place (GST_BASE_TRANSFORM (transform), ip);}

static voidgst_navseek_seek (GstNavSeek * navseek, gint64 offset){  GstFormat peer_format = GST_FORMAT_TIME;  gboolean ret;  GstPad *peer_pad;  gint64 peer_value;  /* Query for the current time then attempt to set to time + offset */  peer_pad = gst_pad_get_peer (GST_BASE_TRANSFORM (navseek)->sinkpad);  ret = gst_pad_query_position (peer_pad, &peer_format, &peer_value);  if (ret && peer_format == GST_FORMAT_TIME) {    GstEvent *event;    peer_value += offset;    if (peer_value < 0)      peer_value = 0;    event = gst_event_new_seek (1.0, GST_FORMAT_TIME,        GST_SEEK_FLAG_ACCURATE | GST_SEEK_FLAG_FLUSH,        GST_SEEK_TYPE_SET, peer_value, GST_SEEK_TYPE_NONE, GST_CLOCK_TIME_NONE);    gst_pad_send_event (peer_pad, event);  }  gst_object_unref (peer_pad);}

static voidgst_video_filter2_init (GstVideoFilter2 * videofilter2,    GstVideoFilter2Class * videofilter2_class){  gst_base_transform_set_qos_enabled (GST_BASE_TRANSFORM (videofilter2), TRUE);}

static voidgst_caps_setter_set_property (GObject * object, guint prop_id,    const GValue * value, GParamSpec * pspec){  GstCapsSetter *filter;  g_return_if_fail (GST_IS_CAPS_SETTER (object));  filter = GST_CAPS_SETTER (object);  switch (prop_id) {    case PROP_CAPS:{      GstCaps *new_caps;      const GstCaps *new_caps_val = gst_value_get_caps (value);      gint i;      if (new_caps_val == NULL) {        new_caps = gst_caps_new_any ();      } else {        new_caps = gst_caps_copy (new_caps_val);      }      for (i = 0; new_caps && (i < gst_caps_get_size (new_caps)); ++i) {        GstStructure *s;        s = gst_caps_get_structure (new_caps, i);        if (!gst_structure_foreach (s, gst_caps_is_fixed_foreach, NULL)) {          GST_ERROR_OBJECT (filter, "rejected unfixed caps: %" GST_PTR_FORMAT,              new_caps);          gst_caps_unref (new_caps);          new_caps = NULL;          break;        }      }      if (new_caps) {        GST_OBJECT_LOCK (filter);        gst_caps_replace (&filter->caps, new_caps);        /* drop extra ref */        gst_caps_unref (new_caps);        GST_OBJECT_UNLOCK (filter);        GST_DEBUG_OBJECT (filter, "set new caps %" GST_PTR_FORMAT, new_caps);      }      /* try to activate these new caps next time around */      gst_base_transform_reconfigure (GST_BASE_TRANSFORM (filter));      break;    }    case PROP_JOIN:      filter->join = g_value_get_boolean (value);      break;    case PROP_REPLACE:      filter->replace = g_value_get_boolean (value);      break;    default:      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);      break;  }}

static gbooleangst_pixbufscale_set_info (GstVideoFilter * filter, GstCaps * in,    GstVideoInfo * in_info, GstCaps * out, GstVideoInfo * out_info){  if (in_info->width == out_info->width && in_info->height == out_info->height) {    gst_base_transform_set_passthrough (GST_BASE_TRANSFORM (filter), TRUE);  } else {    gst_base_transform_set_passthrough (GST_BASE_TRANSFORM (filter), FALSE);  }  GST_DEBUG_OBJECT (filter, "from=%dx%d, size %" G_GSIZE_FORMAT      " -> to=%dx%d, size %" G_GSIZE_FORMAT,      in_info->width, in_info->height, in_info->size,      out_info->width, out_info->height, out_info->size);  return TRUE;}

static voidgst_capsfilter_init (GstCapsFilter * filter){  GstBaseTransform *trans = GST_BASE_TRANSFORM (filter);  gst_base_transform_set_gap_aware (trans, TRUE);  gst_base_transform_set_prefer_passthrough (trans, FALSE);  filter->filter_caps = gst_caps_new_any ();}

/* initialize the new element * instantiate pads and add them to element * set pad calback functions * initialize instance structure */static voidgst_skin_detect_init (GstSkinDetect * filter){  filter->postprocess = TRUE;  filter->method = HSV;  gst_base_transform_set_in_place (GST_BASE_TRANSFORM (filter), FALSE);}

/****************************************************************************** * gst_tidmaiaccel_init *****************************************************************************/static void gst_tidmaiaccel_init (GstTIDmaiaccel *dmaiaccel){    gst_base_transform_set_qos_enabled (GST_BASE_TRANSFORM (dmaiaccel), TRUE);    dmaiaccel->colorSpace = ColorSpace_NOTSET;    dmaiaccel->width = 0;    dmaiaccel->height = 0;    dmaiaccel->bufTabAllocated = FALSE;}

static gbooleangst_audio_fx_base_fir_filter_query (GstPad * pad, GstQuery * query){  GstAudioFXBaseFIRFilter *self =      GST_AUDIO_FX_BASE_FIR_FILTER (gst_pad_get_parent (pad));  gboolean res = TRUE;  switch (GST_QUERY_TYPE (query)) {    case GST_QUERY_LATENCY:    {      GstClockTime min, max;      gboolean live;      guint64 latency;      GstPad *peer;      gint rate = GST_AUDIO_FILTER (self)->format.rate;      if (rate == 0) {        res = FALSE;      } else if ((peer = gst_pad_get_peer (GST_BASE_TRANSFORM (self)->sinkpad))) {        if ((res = gst_pad_query (peer, query))) {          gst_query_parse_latency (query, &live, &min, &max);          GST_DEBUG_OBJECT (self, "Peer latency: min %"              GST_TIME_FORMAT " max %" GST_TIME_FORMAT,              GST_TIME_ARGS (min), GST_TIME_ARGS (max));          if (self->fft && !self->low_latency)            latency = self->block_length - self->kernel_length + 1;          else            latency = self->latency;          /* add our own latency */          latency = gst_util_uint64_scale_round (latency, GST_SECOND, rate);          GST_DEBUG_OBJECT (self, "Our latency: %"              GST_TIME_FORMAT, GST_TIME_ARGS (latency));          min += latency;          if (max != GST_CLOCK_TIME_NONE)            max += latency;          GST_DEBUG_OBJECT (self, "Calculated total latency : min %"              GST_TIME_FORMAT " max %" GST_TIME_FORMAT,              GST_TIME_ARGS (min), GST_TIME_ARGS (max));          gst_query_set_latency (query, live, min, max);        }        gst_object_unref (peer);      }      break;    }    default:      res = gst_pad_query_default (pad, query);      break;  }  gst_object_unref (self);  return res;}

static voidgst_alpha_color_init (GstMillColor * mc, GstMillColorClass * g_class){  GstBaseTransform *btrans = NULL;  btrans = GST_BASE_TRANSFORM (mc);  btrans->always_in_place = TRUE;}

static voidtoggle_passthrough (gpointer data, gpointer user_data){  GstBaseTransform *basetrans = GST_BASE_TRANSFORM (user_data);  gst_base_transform_set_passthrough (basetrans, TRUE);  g_thread_yield ();  gst_base_transform_set_passthrough (basetrans, FALSE);}

static voidgst_cv_smooth_change_type (GstCvSmooth * filter, gint value){  GST_DEBUG_OBJECT (filter, "Changing type from %d to %d", filter->type, value);  if (filter->type == value)    return;  filter->type = value;  switch (value) {    case CV_GAUSSIAN:    case CV_BLUR:      gst_base_transform_set_in_place (GST_BASE_TRANSFORM (filter), TRUE);      break;    default:      gst_base_transform_set_in_place (GST_BASE_TRANSFORM (filter), FALSE);      break;  }}

static voidgst_cv_sobel_init (GstCvSobel * filter){  filter->x_order = DEFAULT_X_ORDER;  filter->y_order = DEFAULT_Y_ORDER;  filter->aperture_size = DEFAULT_APERTURE_SIZE;  gst_base_transform_set_in_place (GST_BASE_TRANSFORM (filter), FALSE);}

/* initialize the new element * instantiate pads and add them to element * set pad calback functions * initialize instance structure */static voidgst_segmentation_init (GstSegmentation * filter){  filter->method = DEFAULT_METHOD;  filter->test_mode = DEFAULT_TEST_MODE;  filter->framecount = 0;  filter->learning_rate = DEFAULT_LEARNING_RATE;  gst_base_transform_set_in_place (GST_BASE_TRANSFORM (filter), TRUE);}

static voidgst_chromaprint_init (GstChromaprint * chromaprint){  gst_base_transform_set_passthrough (GST_BASE_TRANSFORM (chromaprint), TRUE);  chromaprint->context = chromaprint_new (CHROMAPRINT_ALGORITHM_DEFAULT);  chromaprint->fingerprint = NULL;  chromaprint->max_duration = DEFAULT_MAX_DURATION;  gst_chromaprint_reset (chromaprint);}

static voidgst_ffmpegaudioresample_init (GstFFMpegAudioResample * resample,    GstFFMpegAudioResampleClass * klass){  GstBaseTransform *trans = GST_BASE_TRANSFORM (resample);  gst_pad_set_bufferalloc_function (trans->sinkpad, NULL);  resample->res = NULL;}

static voidgst_progress_report_init (GstProgressReport * report){  gst_base_transform_set_passthrough (GST_BASE_TRANSFORM (report), TRUE);  report->update_freq = DEFAULT_UPDATE_FREQ;  report->silent = DEFAULT_SILENT;  report->do_query = DEFAULT_DO_QUERY;  report->format = g_strdup (DEFAULT_FORMAT);}

static voidgst_audio_echo_init (GstAudioEcho * self, GstAudioEchoClass * klass){  self->delay = 1;  self->max_delay = 1;  self->intensity = 0.0;  self->feedback = 0.0;  gst_base_transform_set_in_place (GST_BASE_TRANSFORM (self), TRUE);}

static voidgst_ffmpegscale_init (GstFFMpegScale * scale, GstFFMpegScaleClass * klass){  GstBaseTransform *trans = GST_BASE_TRANSFORM (scale);  gst_pad_set_event_function (trans->srcpad, gst_ffmpegscale_handle_src_event);  scale->pixfmt = PIX_FMT_NB;  scale->res = NULL;}

static voidgst_ofa_init (GstOFA * ofa, GstOFAClass * g_class){  gst_base_transform_set_passthrough (GST_BASE_TRANSFORM (ofa), TRUE);  ofa->fingerprint = NULL;  ofa->record = TRUE;  ofa->adapter = gst_adapter_new ();}

static voidgst_rg_limiter_init (GstRgLimiter * filter, GstRgLimiterClass * gclass){  GstBaseTransform *base = GST_BASE_TRANSFORM (filter);  gst_base_transform_set_passthrough (base, FALSE);  gst_base_transform_set_gap_aware (base, TRUE);  filter->enabled = TRUE;}

static voidgst_audio_panorama_init (GstAudioPanorama * filter){  filter->panorama = 0;  filter->method = METHOD_PSYCHOACOUSTIC;  gst_audio_info_init (&filter->info);  filter->process = NULL;  gst_base_transform_set_gap_aware (GST_BASE_TRANSFORM (filter), TRUE);}

static void webkit_media_playready_decrypt_init(WebKitMediaPlayReadyDecrypt* self){    GstBaseTransform* base = GST_BASE_TRANSFORM(self);    gst_base_transform_set_in_place(base, TRUE);    gst_base_transform_set_passthrough(base, FALSE);    gst_base_transform_set_gap_aware(base, FALSE);    g_mutex_init(&self->mutex);    g_cond_init(&self->condition);}

static voidgst_video_balance_update_properties (GstVideoBalance * videobalance){  gboolean passthrough = gst_video_balance_is_passthrough (videobalance);  GstBaseTransform *base = GST_BASE_TRANSFORM (videobalance);  base->passthrough = passthrough;  if (!passthrough)    gst_video_balance_update_tables (videobalance);}

/* initialize the new element * instantiate pads and add them to element * set pad callback functions * initialize instance structure */static voidgst_cv_smooth_init (GstCvSmooth * filter, GstCvSmoothClass * gclass){  filter->type = DEFAULT_CV_SMOOTH_TYPE;  filter->param1 = DEFAULT_PARAM1;  filter->param2 = DEFAULT_PARAM2;  filter->param3 = DEFAULT_PARAM3;  filter->param4 = DEFAULT_PARAM4;  gst_base_transform_set_in_place (GST_BASE_TRANSFORM (filter), FALSE);}