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快速和慢速操作

warning

我们正在逐步淘汰 Media Parser，并转向使用 Mediabunny！

@remotion/media-parser 允许你指定想要获取的信息。 然后它会尽量少地读取数据以实现目标。

有三种类型的字段：

🌐 There are three types of fields:

  • 仅头部：只需要读取文件的前几个字节。
  • 仅元数据：只需要解析元数据部分
  • 需要完整解析：整个文件将被读取和处理。

显然，处理文件的量越少越快，你应该尽量只读取所需的信息。

🌐 Obviously, processing less of the file is faster and you should aim to read only the information you require.

完整解析操作​

🌐 Full parsing operations

以下 fields 需要读取完整文件：

🌐 The following fields require the full file to be read:

通常，如果一个字段被标记为 slow，则需要读取整个文件。

🌐 Generally, if a field is marked as slow, it will require the full file to be read.

此外，如果传入了onVideoTrack或onAudioTrack处理器，并且任何函数返回一个回调函数，则需要完整解析。

🌐 Also, if an onVideoTrack or onAudioTrack handler is passed, and any function returns an callback function, full parsing is required.

仅元数据操作​

🌐 Metadata-only operations

以下 fields 仅需要解析视频的元数据部分：

🌐 The following fields require only the metadata section of the video to be parsed:

此外，如果传入了 onVideoTrack 或 onAudioTrack 处理程序，则仅在处理程序函数返回 null 时才需要解析元数据部分。

🌐 Also, if an onVideoTrack or onAudioTrack handler is passed, only the parsing of the metadata section is required if null is returned from the handler function.

仅头文件操作​

🌐 Header-only operations

以下 fields 仅需要解析媒体的前几个字节：

🌐 The following fields require only the first few bytes of the media to be parsed:

寻求必需​

🌐 Seeking required

如果你从 URL 加载视频，请确保它们支持 Range 头。
否则，如果元数据位于文件的末尾，@remotion/media-parser 将不得不读取整个文件。

🌐 If you load videos from a URL, make sure that they support the Range header.
Otherwise, @remotion/media-parser has no choice but to read the full file if the metadata is at the end of it.

示例​

🌐 Example

Reading header only
// Some fields only require the first few bytes of the file to be read:
const result = await parseMedia({
  src: 'https://remotion.media/video.mp4',
  fields: {
    size: true,
    container: true,
    internalStats: true,
  },
});

console.log(result.internalStats.finalCursorOffset); // 12

// Reading the metadata of the video will only require the metadata section to be parsed.
// You can also use onVideoTrack() and return null to retrieve track information but to not get the samples.
const result2 = await parseMedia({
  src: 'https://remotion.media/video.mp4',
  fields: {
    durationInSeconds: true,
    dimensions: true,
    internalStats: true,
  },
  onVideoTrack: ({track}) => {
    console.log(track);
    return null;
  },
});

console.log(result2.internalStats.finalCursorOffset); // 4000
console.log(result2.dimensions);

// Asking for all video samples requires parsing the whole file
const result3 = await parseMedia({
  src: 'https://remotion.media/video.mp4',
  fields: {
    internalStats: true,
  },
  onVideoTrack: () => {
    return (videoSample) => console.log(videoSample);
  },
});

console.log(result3.internalStats.finalCursorOffset); // 1870234802

另请参阅​

🌐 See also

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