I'm using the Plupload library to upload audio files to my website from the front-end. Here is an example of my Plupload config:

var uploader = new plupload.Uploader({
    browse_button : 'browse',
    file_data_name : 'async-upload',
    multipart_params: {
        action : 'upload-attachment'
    url : ajax_url,
    flash_swf_url : flash_swf_url,
    silverlight_xap_url : silverlight_xap_url,
    chunk_size : '200kb',
    max_retries : 3

My aim is to break files down into smaller 'chunks' whilst uploading. Plupload has built-in support for this.

My question

An example of server-side chuck handling is provided by Plupload. Does WordPress handle chunks server-side when uploading asynchronously or is this something I have to do myself?

Ref: http://www.plupload.com/docs/Chunking

1 Answer 1


To the best of my knowledge, no, the async-upload process on the WordPress side does not support chunking from plupload. You can find this code in /wp-admin/async-upload.php.

To handle the uploaded file, it calls the wp_ajax_upload_attachment() function, in the ajax-actions.php file. This function refers directly to the PHP $_FILES array, meaning that the file would be completely uploaded and saved to a tmp file by PHP before WordPress is invoked. Therefore chunking is not directly supported.

  • I got as far as async-upload.php myself but had trouble understanding the process from that point onward. You've made things a lot clearer with that explanation. Commented Nov 14, 2014 at 22:59

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