前提

通过阅读【MLT】MLTAnalysis of production and consumption architecture of multimedia framework（一）满足以下两点：

1. 了解MLT的核心C++The encapsulation hierarchy
2. 掌握使用MLT的Consumer（sdl）消费Producer（MP4）

What to get from this article？

本文将对【MLT】MLTAnalysis of production and consumption architecture of multimedia framework（一）How to add video filters to the producer processing link in the production and consumption process mentioned in the analysis,如下图：

核心类解析

Service+Filter

【MLT】MLTAnalysis of production and consumption architecture of multimedia framework（一）Just a simple demonstration of the producer（A video resource is initialized）被消费者（初始化为SDL）Simple process of consumption.如上图所示,Two new encapsulations have been introduced to the process of producer processing：Service（Service abstract base class）+ Filter（Filter abstract service class）.This section only briefly introduces the method we are about to use,These two packages will be fully analyzed later.

// Service abstract base class

/** * @brief attach Method for registering filter service * @param filter The filter service to register * @return Returns the registered error code */
int attach( Filter &filter );
/** * @brief detach The method to unregister the filter service * @param filter Filter service to unregister * @return Returns the unregistered error code */
int detach( Filter &filter );

Add filters for producers

// Create mosaic filters
Mlt::Filter *filter = new Mlt::Filter(profile, "frei0r.pixeliz0r");
// 使用从父类ServiceAdds a filter to the subscription ability inherited from 
producer.attach(*filter);

Demon展示

为Producer（MP4）添加Filter（马赛克）效果

代码

    Profile profile; // defaults to dv_pal
    Producer producer(profile, filename);
    Consumer consumer(profile); // defaults to sdl

    Mlt::Filter *filter = new Mlt::Filter(profile, "frei0r.pixeliz0r");
    producer.attach(*filter);

    // Prevent scaling to the profile size.
    // Let the sdl consumer do all scaling.
    consumer.set("rescale", "none");

    // Automatically exit at end of file.
    consumer.set("terminate_on_pause", 1);

    consumer.connect(producer);
    consumer.run();
    consumer.stop();

Affiliate code download link

源代码下载链接

参考资料

【1】MLT github链接