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Mariusz Klochowicz
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Add first cut of the application
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lines changed

Diff for: ‎CMakeLists.txt

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cmake_minimum_required(VERSION 3.10)
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project(ThreeVideoStream LANGUAGES C)
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add_compile_options(-Wall -Wextra -pedantic -Werror -Wno-unused-parameter)
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# for LSP / clang-tidy etc.
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set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
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set (CMAKE_C_STANDARD 99)
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SET (CMAKE_C_FLAGS_DEBUG "-g -O0")
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# for sanitizer build
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# set (CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -g -O0 -fno-omit-frame-pointer -fsanitize=address")
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# set (CMAKE_LINKER_FLAGS_DEBUG "${CMAKE_LINKER_FLAGS_DEBUG} -fno-omit-frame-pointer -fsanitize=address")
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# Glib
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find_package(PkgConfig REQUIRED)
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pkg_check_modules(GSTLIBS REQUIRED
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gobject-2.0
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glib-2.0
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gstreamer-1.0)
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# add extra include directories
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include_directories(
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/usr/lib/x86_64-linux-gnu/glib-2.0/include
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/usr/include/glib-2.0
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/usr/include/gstreamer-1.0
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)
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link_libraries(gstreamer-1.0
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gobject-2.0
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glib-2.0)
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link_directories(${GSTLIBS_LIBRARY_DIRS})
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set(SOURCE_FILES main.c three_video_stream.h three_video_stream.c gst_helpers.h gst_helpers.c)
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add_executable(ThreeVideoStream ${SOURCE_FILES})
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target_link_libraries(ThreeVideoStream ${ThreeVideoStream_LIBRARIES})

Diff for: ‎README.md

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44

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Example C application utilising GStreamer to mix 3 videos onto one screen and optionally stream the result to Twitch via RTMP.
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Tested on Ubuntu 20.04.
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# Features
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- Mixing 3 videos into one screen (which size can be configured)
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- optional Twitch streaming
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- core functionality is wrapped inside a GObject class, allowing for usage outside of C
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# Usage
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`ThreeVideoStream` object encapsulates all the functionality and exposes a set of properties that can affect the playback.
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Optional properties should be set before the property `ready-to-play` is set.
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Note: `ThreeVideoStream` exposes `GstPipeline *` as one of its properties to allow state monitoring & state changes of the underlying GStreamer pipeline.
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720
# Roadmap
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- [ ] add audio support
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- [ ] implement more layouts (and expose a enum property to change them at runtime)
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- [ ] allow building on MacOS & Windows
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- [ ] add GUI controls (GTK)
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- [ ] allow dynamically reconfiguring the pipeline
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- [ ] add support for streaming to other RMTP services
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- [ ] rewrite in Rust :)
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Diff for: ‎gst_helpers.c

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#include "gst_helpers.h"
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void scale_input_videos(GstreamerData * data, int output_width, int output_height);
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void setup_video_mixer_pads(GstreamerData * data, int output_width, int output_height);
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/* Manually clean unused Gst Elements if not streaming to Twitch */
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/* TODO Create them on-demand instead of eagerly*/
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void clean_unused_streaming_gst_elements(GstreamerData * data);
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GstreamerData create_data()
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{
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GstreamerData data;
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/* Create the elements */
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data.decodebin1 = gst_element_factory_make("uridecodebin3", "decodebin1");
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data.decodebin2 = gst_element_factory_make("uridecodebin3", "decodebin2");
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data.decodebin3 = gst_element_factory_make("uridecodebin3", "decodebin3");
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data.videoscale1 = gst_element_factory_make("videoscale", "videobox1");
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data.videoscale2 = gst_element_factory_make("videoscale", "videobox2");
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data.videoscale3 = gst_element_factory_make("videoscale", "videobox3");
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data.video_scaled_caps1 = gst_element_factory_make("capsfilter", "video_scaled_capsfilter1");
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data.video_scaled_caps2 = gst_element_factory_make("capsfilter", "video_scaled_capsfilter2");
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data.video_scaled_caps3 = gst_element_factory_make("capsfilter", "video_scaled_capsfilter3");
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data.video_mixer = gst_element_factory_make("videomixer", "videomixer");
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data.tee = gst_element_factory_make("tee", "tee");
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/* Live preview */
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data.queue_preview = gst_element_factory_make("queue", "queue_preview");
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data.convert_preview = gst_element_factory_make("videoconvert", "convert_preview");
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data.sink_preview = gst_element_factory_make("autovideosink", "sink_preview");
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/* Twitch streaming */
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data.queue_streaming = gst_element_factory_make("queue", "queue_streaming");
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data.video_encoder_streaming = gst_element_factory_make("x264enc", "encoder_streaming");
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data.queue_encoded = gst_element_factory_make("queue", "queue_encoded");
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data.muxer_streaming = gst_element_factory_make("flvmux", "muxer_streaming");
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data.queue_muxed = gst_element_factory_make("queue", "queue_muxed");
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data.sink_rtmp = gst_element_factory_make("rtmpsink", "sink_streaming");
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data.pipeline = gst_pipeline_new("pipeline");
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if (!data.pipeline || !data.decodebin1 || !data.decodebin2 || !data.decodebin3 //
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|| !data.videoscale1 || !data.videoscale2 || !data.videoscale3 || !data.video_scaled_caps1
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|| !data.video_scaled_caps2 || !data.video_scaled_caps3 || !data.video_mixer || !data.tee //
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|| !data.convert_preview || !data.queue_preview || !data.sink_preview || //
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!data.queue_streaming || !data.video_encoder_streaming || !data.queue_encoded || !data.muxer_streaming
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|| !data.queue_muxed || !data.sink_rtmp) {
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g_printerr("Not all elements could be created.\n");
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exit(1);
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}
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return data;
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}
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void link_pipeline_elements(GstreamerData * data, gboolean with_twitch)
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{
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g_return_if_fail(data != NULL);
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if (with_twitch == FALSE) { clean_unused_streaming_gst_elements(data); }
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gboolean error = FALSE;
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/* Add the common part of the pipeline */
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gst_bin_add_many(GST_BIN(data->pipeline),
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data->decodebin1,
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data->decodebin2,
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data->decodebin3,
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data->videoscale1,
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data->videoscale2,
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data->videoscale3,
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data->video_scaled_caps1,
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data->video_scaled_caps2,
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data->video_scaled_caps3,
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data->video_mixer,
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data->convert_preview,
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data->sink_preview,
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NULL);
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if (!gst_element_link(data->videoscale1, data->video_scaled_caps1)
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|| !gst_element_link(data->videoscale2, data->video_scaled_caps2)
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|| !gst_element_link(data->videoscale3, data->video_scaled_caps3)) {
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error = TRUE;
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}
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if (with_twitch) {
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gst_bin_add_many(GST_BIN(data->pipeline),
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data->tee,
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data->queue_preview,
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data->queue_streaming,
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data->video_encoder_streaming,
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data->queue_encoded,
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data->muxer_streaming,
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data->queue_muxed,
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data->sink_rtmp,
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NULL);
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g_print("Linking GStreamer elements for live preview and Twitch streaming .\n");
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if (!gst_element_link_many(data->video_mixer, data->tee, NULL)
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|| !gst_element_link_many(data->tee,
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data->queue_streaming,
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data->video_encoder_streaming,
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data->queue_encoded,
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data->muxer_streaming,
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data->queue_muxed,
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data->sink_rtmp,
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NULL)
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|| !gst_element_link_many(data->tee,
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data->queue_preview,
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data->convert_preview,
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data->sink_preview,
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NULL)) {
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error = TRUE;
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}
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}
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else {
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g_print("Linking the elements without Twitch streaming part.\n");
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if (!gst_element_link_many(data->video_mixer, data->convert_preview, data->sink_preview, NULL)) {
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error = TRUE;
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}
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}
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if (error) {
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g_printerr("Elements could not be linked.\n");
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gst_object_unref(data->pipeline);
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exit(1);
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}
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}
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void setup_video_placement(GstreamerData * data, int output_width, int output_height)
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{
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g_return_if_fail(data != NULL);
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g_object_set(data->video_mixer, "background", 1, NULL); /* set black background beneath */
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scale_input_videos(data, output_width, output_height);
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setup_video_mixer_pads(data, output_width, output_height);
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}
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void setup_file_sources(GstreamerData * data, gchar * file_path1, gchar * file_path2, gchar * filepath3)
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{
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g_return_if_fail(data != NULL);
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g_return_if_fail(file_path1 != NULL || file_path2 != NULL || filepath3 != NULL);
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gchar * uri1 = g_strjoin("", "file://", file_path1, NULL);
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gchar * uri2 = g_strjoin("", "file://", file_path2, NULL);
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gchar * uri3 = g_strjoin("", "file://", filepath3, NULL);
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g_object_set(data->decodebin1, "uri", uri1, NULL);
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g_object_set(data->decodebin2, "uri", uri2, NULL);
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g_object_set(data->decodebin3, "uri", uri3, NULL);
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g_free(uri1);
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g_free(uri2);
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g_free(uri3);
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}
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void setup_twitch_streaming(GstreamerData * data, gchar * twitch_api_key, gchar * twitch_server)
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{
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g_return_if_fail(data != NULL);
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g_return_if_fail(twitch_api_key != NULL || twitch_server != NULL);
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/* Set the parameters for the Twitch stream */
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g_object_set(data->video_encoder_streaming, "threads", 0, NULL);
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g_object_set(data->video_encoder_streaming, "bitrate", 400, NULL);
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g_object_set(data->video_encoder_streaming, "tune", 4, NULL);
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g_object_set(data->video_encoder_streaming, "key-int-max", 30, NULL);
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g_object_set(data->muxer_streaming, "streamable", TRUE, NULL);
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gchar * location = g_strjoin("", twitch_server, twitch_api_key, NULL);
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g_object_set(data->sink_rtmp, "location", location, NULL);
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g_free(location);
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}
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void clean_unused_streaming_gst_elements(GstreamerData * data)
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{
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g_return_if_fail(data != NULL);
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gst_object_unref(data->tee);
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gst_object_unref(data->queue_preview);
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gst_object_unref(data->queue_streaming);
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gst_object_unref(data->video_encoder_streaming);
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gst_object_unref(data->queue_encoded);
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gst_object_unref(data->muxer_streaming);
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gst_object_unref(data->queue_muxed);
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gst_object_unref(data->sink_rtmp);
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}
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void try_change_pipeline_state(GstElement * pipeline, GstState state)
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{
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GstStateChangeReturn ret = gst_element_set_state(pipeline, state);
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if (ret == GST_STATE_CHANGE_FAILURE) {
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g_printerr("Unable to set the pipeline to the paused state.\n");
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gst_object_unref(pipeline);
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exit(1);
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}
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}
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/* private functions' definitions */
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void scale_input_videos(GstreamerData * data, int output_width, int output_height)
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{
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GstCaps * videocaps_half = gst_caps_new_simple("video/x-raw",
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"format",
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G_TYPE_STRING,
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"I420",
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"framerate",
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GST_TYPE_FRACTION,
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25,
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1,
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"pixel-aspect-ratio",
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GST_TYPE_FRACTION,
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1,
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1,
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"width",
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G_TYPE_INT,
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output_width / 2,
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"height",
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G_TYPE_INT,
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output_height / 2,
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NULL);
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g_object_set(data->video_scaled_caps1, "caps", videocaps_half, NULL);
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g_object_set(data->video_scaled_caps2, "caps", videocaps_half, NULL);
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g_object_set(data->video_scaled_caps3, "caps", videocaps_half, NULL);
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gst_caps_unref(videocaps_half);
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}
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void setup_video_mixer_pads(GstreamerData * data, int output_width, int output_height)
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{
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/* Manually link the videomixer, which has "Request" pads */
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GstPad *videomixer_pad1, *video1_pad = NULL;
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GstPad *videomixer_pad2, *video2_pad = NULL;
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GstPad *videomixer_pad3, *video3_pad = NULL;
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videomixer_pad1 = gst_element_get_request_pad(data->video_mixer, "sink_%u");
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videomixer_pad2 = gst_element_get_request_pad(data->video_mixer, "sink_%u");
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videomixer_pad3 = gst_element_get_request_pad(data->video_mixer, "sink_%u");
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video1_pad = gst_element_get_static_pad(data->video_scaled_caps1, "src");
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video2_pad = gst_element_get_static_pad(data->video_scaled_caps2, "src");
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video3_pad = gst_element_get_static_pad(data->video_scaled_caps3, "src");
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if (gst_pad_link(video1_pad, videomixer_pad1) != GST_PAD_LINK_OK
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|| gst_pad_link(video2_pad, videomixer_pad2) != GST_PAD_LINK_OK
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|| gst_pad_link(video3_pad, videomixer_pad3) != GST_PAD_LINK_OK) {
245+
g_printerr("Videomixer could not be linked.\n");
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gst_object_unref(data->pipeline);
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exit(1);
248+
}
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g_object_set(videomixer_pad1, "xpos", 0, NULL);
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g_object_set(videomixer_pad1, "ypos", output_height / 4, NULL);
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g_object_set(videomixer_pad2, "xpos", output_width / 2, NULL);
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g_object_set(videomixer_pad2, "ypos", 0, NULL);
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g_object_set(videomixer_pad3, "xpos", output_width / 2, NULL);
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g_object_set(videomixer_pad3, "ypos", output_height / 2, NULL);
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gst_object_unref(videomixer_pad1);
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gst_object_unref(videomixer_pad2);
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gst_object_unref(videomixer_pad3);
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gst_object_unref(video1_pad);
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gst_object_unref(video2_pad);
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gst_object_unref(video3_pad);
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}

Diff for: ‎gst_helpers.h

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#ifndef _GST_HELPERS__H_
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#define _GST_HELPERS__H_
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#include <gst/gst.h>
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/* Structure to contain all our information, so we can pass it to callbacks */
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typedef struct _GstreamerData {
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GstElement * pipeline;
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GstElement * decodebin1;
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GstElement * decodebin2;
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GstElement * decodebin3;
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GstElement * videoscale1;
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GstElement * videoscale2;
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GstElement * videoscale3;
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GstElement * video_scaled_caps1;
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GstElement * video_scaled_caps2;
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GstElement * video_scaled_caps3;
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GstElement * video_mixer;
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GstElement * convert_preview;
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GstElement * sink_preview;
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// XXX Do not call the following if Twitch is not setup
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GstElement * tee;
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GstElement * queue_preview;
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GstElement * queue_streaming;
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GstElement * video_encoder_streaming;
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GstElement * queue_encoded;
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GstElement * muxer_streaming;
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GstElement * queue_muxed;
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GstElement * sink_rtmp;
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} GstreamerData;
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/* A factory function that creates all necessary GstElements, struct */
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/* Exits on error. */
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GstreamerData create_data();
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void link_pipeline_elements(GstreamerData * data, gboolean with_twitch);
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void setup_video_placement(GstreamerData * data, int output_width, int output_height);
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void setup_file_sources(GstreamerData * data, gchar * filepath1, gchar * filepath2, gchar * filepath3);
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void setup_twitch_streaming(GstreamerData * data, gchar * twitch_api_key, gchar * twich_server);
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void clean_unused_streaming_gst_elements(GstreamerData * data);
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/* Try to change pipeline state to desired state */
47+
/* Exits the program if request cannot be fulfilled */
48+
void try_change_pipeline_state(GstElement * pipeline, GstState state);
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#endif /* _GST_HELPERS__H_ */

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