Скачать или смотреть How to Use QMediaMetaData Correctly to Define Media File Parameters in Qt

Learn how to efficiently utilize `QMediaMetaData` in your Qt application to define and retrieve audio file parameters such as bitrate, sampling rate, and more.
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This video is based on the question https://stackoverflow.com/q/64016809/ asked by the user 'Helg1980' ( https://stackoverflow.com/u/14109530/ ) and on the answer https://stackoverflow.com/a/64037175/ provided by the user 'Mehran Khazaeizadeh' ( https://stackoverflow.com/u/5733707/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Use QMediaMetaData Correctly to Define Media File Parameters in Qt

When working with media files in a Qt application, understanding how to manage and retrieve metadata is crucial. If you're trying to determine parameters such as bitrate, sampling rate, and audio format, you may run into issues if you don’t utilize the right classes and methods. In this guide, we will explore how to use the QMediaMetaData class correctly within the context of a QMediaPlayer to achieve the desired results.

The Problem

You may have attempted to use QMediaObject for handling media files and extracting their metadata. However, errors such as "no matching constructor for initialization of QMediaObject" can hinder your progress. This typically happens because QMediaObject is not intended to be instantiated directly. Instead, you should use QMediaPlayer for media playback and metadata retrieval.

The Solution

To successfully retrieve media file parameters using QMediaMetaData, follow these organized steps using QMediaPlayer:

Step 1: Define a Media Player Variable

In your main window class, you need to declare a pointer to a QMediaPlayer:

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Step 2: Initialize the Media Player

In the constructor of your main window or during an appropriate initialization phase, create an instance of QMediaPlayer and connect its signals:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Define the Media Status Change Function

You need to monitor the status of the media player and retrieve metadata when the media is loaded:

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Write the GetMetaData Function

This function will access the metadata of the media and print it out:

[[See Video to Reveal this Text or Code Snippet]]

Example Output

When you run your application with a valid media file, you might see output like this in your debug console:

[[See Video to Reveal this Text or Code Snippet]]

This output confirms that you have successfully retrieved the audio parameters using the QMediaMetaData class.

Conclusion

By using QMediaPlayer instead of QMediaObject, you can effectively retrieve important metadata about multimedia files in your Qt application. Follow the outlined steps to ensure that you're accessing metadata correctly. Now, you’ll have all the requisite audio file parameters at your fingertips, significantly enhancing your media playback functionalities in Qt.