Error when using FileSystemWritableFileStreamTarget

[Mat-thieu]

The following error:

Occurs when trying to use FileSystemWritableFileStreamTarget with fileWriter.

This write function (in the build code) is expecting a blob not an object

For now I've worked around the issue by wrapping the fileWriter

   const wrapFileWriter = (fileWriter) => {
        const originalWrite = fileWriter.write;
        const modifiedWrite = (payload) => {
            const blob = new Blob([payload.data]);
            originalWrite.call(fileWriter, blob);
        }
        fileWriter.write = modifiedWrite;
        return fileWriter;
    };
    let muxer = new Mp4Muxer.Muxer({
    target: new Mp4Muxer.FileSystemWritableFileStreamTarget(wrapFileWriter(fileWriter)),
        ...
    }

[Vanilagy]

The FileSystemWritableFileStreamTarget expects a FileSystemWritableFileStream as a parameter! Its write method also accepts ArrayBuffers as input.

It seems like you are passing it something else. How are you getting your fileWriter?

[Mat-thieu]

@Vanilagy

Aah right, I see! Indeed I'm passing a different object. I'm passing it a FileWriter which is returned from a fileEntry.createWriter directly.

I'm obtaining this fileEntry from the following code

export default function requestTempFile(name, sizeInMb) {
    return new Promise((resolve) => {
        const fileSystem = (window.requestFileSystem || window.webkitRequestFileSystem);
        fileSystem(window.TEMPORARY, sizeInMb * 1024 * 1024, (fs) => {
            fs.root.getFile(name, { create: true }, (fileEntry) => {
                resolve(fileEntry);
            });
        });
    });
}

Which is a non-standard, chromium-specific way of creating a sandboxed file.

It's a slightly different use case, it can likely just be handled by the StreamTarget directly

[Vanilagy]

Yes exactly, these custom cases are supposed to be handled by StreamTarget. It'll be very easy and quick to use! In fact, FileSystemWritableFileStreamTarget is nothing but a very thin wrapper around StreamTarget.

[Vanilagy]

Has your issue been resolved?

[Vanilagy]

I'll close this issue for now as it seems stale, so I assume your issue has been resolved. If you still need help with something, feel free to reopen it :)