重新调整mp4并以编程方式使用ffmpeg更改分辨率(Remuxing mp4 and change resolution with ffmpeg programmatically)

重新调整mp4并以编程方式使用ffmpeg更改分辨率(Remuxing mp4 and change resolution with ffmpeg programmatically)

我有一个从ffmpeg工作的remuxing.c示例，但我需要更改分辨率以最小化文件大小，任何人都可以解释我该怎么做？ 或者，如果有另一种方法来“压缩”没有命令行的mp4文件？ 我是FFmpeg的开销者，需要将视频文件从android发送到服务器，我正在部署NDK库来完成这项工作，因为FFmpeg命令行实现有一些限制并且非常慢。

谢谢

I have a remuxing.c example working from ffmpeg but I need to change resolution to minimize file size, anybody can explain me how to do that? Or if there is another way to "compress" mp4 files without command line? I'm a begginer with FFmpeg and need to send video files from android to server, and I'm deploying a NDK library to make this job because FFmpeg command-line implementation have some limitations and is very slow.

Thanks

最满意答案

您应该查看过滤视频和转码示例。 第一个介绍了如何在ffmpeg中添加“过滤器”。 它包括一个缩放滤镜，可将视频重新缩放到给定的分辨率。 转码包括一些过滤，您实际上可以将filter_spec字符串更改为您想要的任何内容，并且程序应该缩放您的输入视频。

这可能不是最好的解决方案，我自己发现它，但它至少会向您介绍正在使用的组件。

You should take a look at the filtering video and the transcoding examples. The first one goes through how you add "filters" in ffmpeg. It includes a scaling filter, which will rescale the video to a given resolution. Transcoding includes some filtering, and you can actually change the filter_spec string to be whatever you want, and the program should scale your input video.

This is probably not the best solution, I just found it myself, but it at least introduces you to the components being used.