GStreamer —— 2.17、Windows下Qt加载GStreamer库后运行 - “播放教程 5：色彩平衡“（附：完整源码）

运行效果

 

介绍

     亮度、对比度、色相和饱和度是常见的视频调整， 在 GStreamer 中统称为 Color Balance 设置。 本教程展示了：

          • 如何找出可用的色彩平衡通道

          • 如何更改它们

     允许访问颜色平衡设置。如果 元素支持这个接口，只需将其转发给应用程序，否则会有一个 colorbalance 元素插入到管道中。

 

GStreamer相关运行库

INCLUDEPATH += D:/Software/GStreamer/1.0/mingw_x86_64/include/gstreamer-1.0/gst
INCLUDEPATH += D:/Software/GStreamer/1.0/mingw_x86_64/include
INCLUDEPATH += D:/Software/GStreamer/1.0/mingw_x86_64/include/gstreamer-1.0
INCLUDEPATH += D:/Software/GStreamer/1.0/mingw_x86_64/include/glib-2.0
INCLUDEPATH += D:/Software/GStreamer/1.0/mingw_x86_64/lib/glib-2.0/includeLIBS += D:/Software/GStreamer/1.0/mingw_x86_64/lib/gstreamer-1.0.lib
LIBS += D:/Software/GStreamer/1.0/mingw_x86_64/lib/glib-2.0.lib
LIBS += D:/Software/GStreamer/1.0/mingw_x86_64/lib/gobject-2.0.lib

 

源码

#include <string.h>
#include <stdio.h>
#include <gst/gst.h>
#include <gst/video/colorbalance.h>typedef struct _CustomData
{GstElement *pipeline;GMainLoop *loop;
} CustomData;/* 处理色彩平衡命令 */
static void update_color_channel (const gchar *channel_name, gboolean increase, GstColorBalance *cb)
{GstColorBalanceChannel *channel = NULL;/* 检索频道列表并找到所请求的频道 */const GList *channels = gst_color_balance_list_channels (cb);for (const GList *l = channels; l != NULL; l = l->next){GstColorBalanceChannel *tmp = (GstColorBalanceChannel *)l->data;if (g_strrstr (tmp->label, channel_name)){channel = tmp;break;}}if (!channel){return;}/* 更改通道值 */gdouble step = 0.1 * (channel->max_value - channel->min_value);gint value = gst_color_balance_get_value (cb, channel);if (increase){value = (gint)(value + step);if (value > channel->max_value)value = channel->max_value;}else{value = (gint)(value - step);if (value < channel->min_value)value = channel->min_value;}gst_color_balance_set_value (cb, channel, value);
}/* Output the current values of all Color Balance channels */
static void print_current_values (GstElement *pipeline)
{/* 输出所有色彩平衡通道的当前值 */const GList *channels = gst_color_balance_list_channels (GST_COLOR_BALANCE (pipeline));for (const GList *l = channels; l != NULL; l = l->next){GstColorBalanceChannel *channel = (GstColorBalanceChannel *)l->data;gint value = gst_color_balance_get_value (GST_COLOR_BALANCE (pipeline), channel);g_print ("%s: %3d%% ", channel->label, 100 * (value - channel->min_value) / (channel->max_value - channel->min_value));}g_print ("\n");
}/* 处理键盘输入 */
static gboolean handle_keyboard (GIOChannel *source, GIOCondition cond, CustomData *data)
{gchar *str = NULL;if (g_io_channel_read_line (source, &str, NULL, NULL, NULL) != G_IO_STATUS_NORMAL) {  return TRUE; }switch (g_ascii_tolower (str[0])){case 'c':update_color_channel ("CONTRAST", g_ascii_isupper (str[0]), GST_COLOR_BALANCE (data->pipeline));break;case 'b':update_color_channel ("BRIGHTNESS", g_ascii_isupper (str[0]), GST_COLOR_BALANCE (data->pipeline));break;case 'h':update_color_channel ("HUE", g_ascii_isupper (str[0]), GST_COLOR_BALANCE (data->pipeline));break;case 's':update_color_channel ("SATURATION", g_ascii_isupper (str[0]), GST_COLOR_BALANCE (data->pipeline));break;case 'q':g_main_loop_quit (data->loop);break;default:break;}g_free (str);print_current_values (data->pipeline);return TRUE;
}int main(int argc, char *argv[])
{/* 初始化GStreamer */gst_init (&argc, &argv);/* 初始化数据结构 */CustomData data;memset (&data, 0, sizeof (data));/* 打印按键功能 */g_print ("USAGE: Choose one of the following options, then press enter:\n"" 'C' to increase contrast, 'c' to decrease contrast\n"" 'B' to increase brightness, 'b' to decrease brightness\n"" 'H' to increase hue, 'h' to decrease hue\n"" 'S' to increase saturation, 's' to decrease saturation\n"" 'Q' to quit\n");/* 构建管道 */data.pipeline = gst_parse_launch ("playbin uri=https://gstreamer.freedesktop.org/data/media/sintel_trailer-480p.webm", NULL);/* 添加键盘监视器，以便我们收到按键通知 */
#ifdef G_OS_WIN32GIOChannel *io_stdin = g_io_channel_win32_new_fd (fileno (stdin));
#elseGIOChannel *io_stdin = g_io_channel_unix_new (fileno (stdin));
#endifg_io_add_watch (io_stdin, G_IO_IN, (GIOFunc)handle_keyboard, &data);/* 开始播放 */GstStateChangeReturn ret = gst_element_set_state (data.pipeline, GST_STATE_PLAYING);if (ret == GST_STATE_CHANGE_FAILURE){g_printerr ("Unable to set the pipeline to the playing state.\n");gst_object_unref (data.pipeline);return -1;}print_current_values (data.pipeline);/* 创建GLib主循环 */data.loop = g_main_loop_new (NULL, FALSE);g_main_loop_run (data.loop);/* 释放资源 */g_main_loop_unref (data.loop);g_io_channel_unref (io_stdin);gst_element_set_state (data.pipeline, GST_STATE_NULL);gst_object_unref (data.pipeline);return 0;
}

 

关注

笔者 - jxd