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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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convertframe: Use refcounting for the context
While this creates a circular reference between the pipeline and the context, this ensures that the context stays alive for as long as any callbacks could be called on it. The circular reference is broken once the conversion is finished (or error, or timeout), which will then cause everything to be freed. Previously it was possible that a callback could be called on the context right after it was freed already. Also use only a single context structure, the second structure does not simplify anything and duplicates storage.
This commit is contained in:
Sebastian Dröge
Sebastian Dröge
parent
9be278d4f5
commit
98109bd5de
1 changed files with 103 additions and 79 deletions
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@ -418,6 +418,7 @@ no_pipeline:
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typedef struct
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{
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gint ref_count;
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GMutex mutex;
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GstElement *pipeline;
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GstVideoConvertSampleCallback callback;
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@ -425,57 +426,60 @@ typedef struct
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GDestroyNotify destroy_notify;
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GMainContext *context;
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GstSample *sample;
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//GstBuffer *buffer;
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GSource *timeout_source;
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gboolean finished;
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/* Results */
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GstSample *converted_sample;
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GError *error;
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} GstVideoConvertSampleContext;
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typedef struct
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static GstVideoConvertSampleContext *
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gst_video_convert_frame_context_ref (GstVideoConvertSampleContext * ctx)
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{
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GstVideoConvertSampleCallback callback;
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GstSample *sample;
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//GstBuffer *buffer;
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GError *error;
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gpointer user_data;
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GDestroyNotify destroy_notify;
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g_atomic_int_inc (&ctx->ref_count);
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GstVideoConvertSampleContext *context;
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} GstVideoConvertSampleCallbackContext;
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return ctx;
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}
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static void
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gst_video_convert_frame_context_free (GstVideoConvertSampleContext * ctx)
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gst_video_convert_frame_context_unref (GstVideoConvertSampleContext * ctx)
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{
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/* Wait until all users of the mutex are done */
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g_mutex_lock (&ctx->mutex);
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g_mutex_unlock (&ctx->mutex);
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if (!g_atomic_int_dec_and_test (&ctx->ref_count))
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return;
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g_mutex_clear (&ctx->mutex);
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if (ctx->timeout_source)
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g_source_destroy (ctx->timeout_source);
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//if (ctx->buffer)
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// gst_buffer_unref (ctx->buffer);
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if (ctx->sample)
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gst_sample_unref (ctx->sample);
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if (ctx->converted_sample)
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gst_sample_unref (ctx->converted_sample);
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g_clear_error (&ctx->error);
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g_main_context_unref (ctx->context);
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gst_element_set_state (ctx->pipeline, GST_STATE_NULL);
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gst_object_unref (ctx->pipeline);
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/* The pipeline was already destroyed in finish() earlier and we
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* must not end up here without finish() being called */
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g_warn_if_fail (ctx->pipeline == NULL);
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g_slice_free (GstVideoConvertSampleContext, ctx);
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}
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static void
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gst_video_convert_frame_callback_context_free
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(GstVideoConvertSampleCallbackContext * ctx)
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{
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if (ctx->context)
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gst_video_convert_frame_context_free (ctx->context);
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g_slice_free (GstVideoConvertSampleCallbackContext, ctx);
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}
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static gboolean
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convert_frame_dispatch_callback (GstVideoConvertSampleCallbackContext * ctx)
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convert_frame_dispatch_callback (GstVideoConvertSampleContext * ctx)
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{
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ctx->callback (ctx->sample, ctx->error, ctx->user_data);
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GstSample *sample;
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GError *error;
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g_return_val_if_fail (ctx->converted_sample != NULL
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|| ctx->error != NULL, FALSE);
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sample = ctx->converted_sample;
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error = ctx->error;
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ctx->converted_sample = NULL;
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ctx->error = NULL;
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ctx->callback (sample, error, ctx->user_data);
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if (ctx->destroy_notify)
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ctx->destroy_notify (ctx->user_data);
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@ -483,34 +487,52 @@ convert_frame_dispatch_callback (GstVideoConvertSampleCallbackContext * ctx)
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return FALSE;
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}
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static gboolean
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convert_frame_stop_pipeline (GstElement * element)
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{
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gst_element_set_state (element, GST_STATE_NULL);
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return FALSE;
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}
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static void
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convert_frame_finish (GstVideoConvertSampleContext * context,
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GstSample * sample, GError * error)
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{
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GSource *source;
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GstVideoConvertSampleCallbackContext *ctx;
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g_return_if_fail (!context->finished);
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g_return_if_fail (sample != NULL || error != NULL);
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context->finished = TRUE;
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context->converted_sample = sample;
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context->error = error;
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if (context->timeout_source)
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g_source_destroy (context->timeout_source);
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context->timeout_source = NULL;
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ctx = g_slice_new (GstVideoConvertSampleCallbackContext);
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ctx->callback = context->callback;
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ctx->user_data = context->user_data;
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ctx->destroy_notify = context->destroy_notify;
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ctx->sample = sample;
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//ctx->buffer = buffer;
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ctx->error = error;
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ctx->context = context;
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source = g_timeout_source_new (0);
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g_source_set_callback (source,
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(GSourceFunc) convert_frame_dispatch_callback, ctx,
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(GDestroyNotify) gst_video_convert_frame_callback_context_free);
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(GSourceFunc) convert_frame_dispatch_callback,
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gst_video_convert_frame_context_ref (context),
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(GDestroyNotify) gst_video_convert_frame_context_unref);
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g_source_attach (source, context->context);
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g_source_unref (source);
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context->finished = TRUE;
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/* Asynchronously stop the pipeline here: this will set its
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* state to NULL and get rid of its last reference, which in turn
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* will get rid of all remaining references to our context and free
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* it too. We can't do this directly here as we might be called from
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* a streaming thread. */
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if (context->pipeline) {
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source = g_timeout_source_new (0);
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g_source_set_callback (source,
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(GSourceFunc) convert_frame_stop_pipeline,
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context->pipeline, (GDestroyNotify) gst_object_unref);
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g_source_attach (source, context->context);
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g_source_unref (source);
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context->pipeline = NULL;
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}
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}
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static gboolean
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@ -596,11 +618,11 @@ convert_frame_need_data_callback (GstElement * src, guint size,
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convert_frame_finish (context, NULL, error);
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}
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g_signal_handlers_disconnect_by_func (src, convert_frame_need_data_callback,
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context);
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done:
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g_mutex_unlock (&context->mutex);
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g_signal_handlers_disconnect_by_func (src, convert_frame_need_data_callback,
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context);
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}
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static GstFlowReturn
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@ -623,12 +645,12 @@ convert_frame_new_preroll_callback (GstElement * sink,
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}
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convert_frame_finish (context, sample, error);
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g_signal_handlers_disconnect_by_func (sink, convert_frame_need_data_callback,
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context);
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done:
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g_mutex_unlock (&context->mutex);
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g_signal_handlers_disconnect_by_func (sink, convert_frame_need_data_callback,
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context);
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return GST_FLOW_OK;
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}
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@ -696,69 +718,71 @@ gst_video_convert_sample_async (GstSample * sample,
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gst_caps_append_structure (to_caps_copy, s);
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}
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pipeline =
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build_convert_frame_pipeline (&src, &sink, from_caps,
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gst_buffer_get_video_crop_meta (buf), to_caps_copy, &error);
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if (!pipeline)
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goto no_pipeline;
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bus = gst_element_get_bus (pipeline);
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/* There's a reference cycle between the context and the pipeline, which is
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* broken up once the finish() is called on the context. At latest when the
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* timeout triggers the context will be freed */
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ctx = g_slice_new0 (GstVideoConvertSampleContext);
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ctx->ref_count = 1;
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g_mutex_init (&ctx->mutex);
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//ctx->buffer = gst_buffer_ref (buf);
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ctx->sample = gst_sample_ref (sample);
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ctx->callback = callback;
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ctx->user_data = user_data;
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ctx->destroy_notify = destroy_notify;
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ctx->context = g_main_context_ref (context);
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ctx->finished = FALSE;
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pipeline =
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build_convert_frame_pipeline (&src, &sink, from_caps,
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gst_buffer_get_video_crop_meta (buf), to_caps_copy, &error);
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if (!pipeline)
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goto no_pipeline;
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ctx->pipeline = pipeline;
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bus = gst_element_get_bus (pipeline);
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if (timeout != GST_CLOCK_TIME_NONE) {
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ctx->timeout_source = g_timeout_source_new (timeout / GST_MSECOND);
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g_source_set_callback (ctx->timeout_source,
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(GSourceFunc) convert_frame_timeout_callback, ctx, NULL);
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(GSourceFunc) convert_frame_timeout_callback,
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gst_video_convert_frame_context_ref (ctx),
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(GDestroyNotify) gst_video_convert_frame_context_unref);
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g_source_attach (ctx->timeout_source, context);
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}
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g_signal_connect (src, "need-data",
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G_CALLBACK (convert_frame_need_data_callback), ctx);
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g_signal_connect (sink, "new-preroll",
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G_CALLBACK (convert_frame_new_preroll_callback), ctx);
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g_signal_connect_data (src, "need-data",
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G_CALLBACK (convert_frame_need_data_callback),
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gst_video_convert_frame_context_ref (ctx),
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(GClosureNotify) gst_video_convert_frame_context_unref, 0);
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g_signal_connect_data (sink, "new-preroll",
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G_CALLBACK (convert_frame_new_preroll_callback),
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gst_video_convert_frame_context_ref (ctx),
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(GClosureNotify) gst_video_convert_frame_context_unref, 0);
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source = gst_bus_create_watch (bus);
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g_source_set_callback (source, (GSourceFunc) convert_frame_bus_callback,
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ctx, NULL);
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gst_video_convert_frame_context_ref (ctx),
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(GDestroyNotify) gst_video_convert_frame_context_unref);
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g_source_attach (source, context);
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g_source_unref (source);
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gst_object_unref (bus);
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gst_element_set_state (pipeline, GST_STATE_PLAYING);
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gst_object_unref (bus);
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gst_caps_unref (to_caps_copy);
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gst_video_convert_frame_context_unref (ctx);
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return;
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/* ERRORS */
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no_pipeline:
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{
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GstVideoConvertSampleCallbackContext *ctx;
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GSource *source;
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gst_caps_unref (to_caps_copy);
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ctx = g_slice_new0 (GstVideoConvertSampleCallbackContext);
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ctx->callback = callback;
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ctx->user_data = user_data;
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ctx->destroy_notify = destroy_notify;
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ctx->sample = NULL;
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ctx->error = error;
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g_mutex_lock (&ctx->mutex);
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convert_frame_finish (ctx, NULL, error);
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g_mutex_unlock (&ctx->mutex);
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gst_video_convert_frame_context_unref (ctx);
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source = g_timeout_source_new (0);
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g_source_set_callback (source,
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(GSourceFunc) convert_frame_dispatch_callback, ctx,
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(GDestroyNotify) gst_video_convert_frame_callback_context_free);
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g_source_attach (source, context);
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g_source_unref (source);
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return;
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}
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}
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