Getting garbled output with incorrect filesize

No worries, just found it interesting the other plugin does work.
If it’s a server issue, any idea on where I might look to see if I can fix this?
As said before, I’d much rather use yours, as the styling options are much better…

Thanks for your time!

Alright, I’ll have a play around with it on my dev (identical) server, see if I can get something going. Thanks for pointing me in the right direction!

Guess we’ll find out, will have a look tomorrow. Thanks!

Fixed it. My own previous reply gave me the idea that it might have something to do with output buffering, and whaddaya know? That’s exactly it.

Added the following right after the initial header() declarations and before where the buffer gets echo’ed to the user, around line 504 in functions.php :
ob_clean();
ob_end_flush();

Solved all the problems I was having. Files now download exactly as intended. Hope this helps someone else with the same issues.

I suspect there are some other plugins that use buffering and are not closing their buffers correctly. So completely flushing the output buffer before filling it up again with the contents of the attachment seems to have done the trick.

Below is what the download function in my case looks like right now. It’s a mashup between your original function, the other plugin’s download function, and a few custom things here and there. Probably could be cleaned up quite a bit, but meh. Perhaps it can help someone else…

/**
 * Process attachment download function
 * 
 * @param 	int $attachment_id
 * @return 	mixed
 */
function da_download_attachment( $attachment_id = 0) {
	if ( get_post_type( $attachment_id ) === 'attachment' ) {
		$uploads = wp_upload_dir();
		$attachment = get_post_meta( $attachment_id, '_wp_attached_file', true );
		$filepath = $uploads['basedir'] . '/' . $attachment;
		$speed = 0;

		$filepath = apply_filters( 'da_download_attachment_filepath', $filepath, $attachment_id );

		if ( ! file_exists( $filepath ) || ! is_readable( $filepath ) )
			return false;

		// if filename contains folders
		if ( ( $position = strrpos( $attachment, '/', 0 ) ) !== false ) {
			$filename = substr( $attachment, $position + 1 );
		} else {
			$filename = $attachment;
		}

	    $mdata = wp_check_filetype($filename);
	    $content_type = $mdata['type'];

	    $buffer = $speed ? $speed : 1024;
		$buffer *= 1024; // in bytes
	    $bandwidth = 0;

	    if (file_exists($filepath))
	        $fsize = filesize($filepath);
	    else
	        $fsize = 0;

		if ( ini_get( 'zlib.output_compression' ) )
			ini_set( 'zlib.output_compression', 0 );

		nocache_headers();
		header( "X-Robots-Tag: noindex, nofollow", true );
		header("Robots: none");
		header("Content-type: $content_type");
		header("Content-disposition: attachment;filename=\"{$filename}\"");
		header("Content-Transfer-Encoding: binary");

		ob_clean();
		ob_end_flush();

	    if( ( isset($_REQUEST['play']) && strpos($_SERVER['HTTP_USER_AGENT'],"Safari") ) ) {
	        readfile($filepath);
	        die();
	    }

		$file = @fopen($filepath, "rb");

	    //check if http_range is sent by browser (or download manager)
	    if (isset($_SERVER['HTTP_RANGE']) && $fsize > 0) {
	        list($bytes, $http_range) = explode("=", $_SERVER['HTTP_RANGE']);
	        $set_pointer = intval(array_shift($tmp = explode('-', $http_range)));
	
	        $new_length = $fsize - $set_pointer;
	
	        header("Accept-Ranges: bytes");
	        header("HTTP/1.1 206 Partial Content");
	
	        header("Content-Length: $new_length");
	        header("Content-Range: bytes $http_range$fsize/$fsize");
	
	        fseek($file, $set_pointer);
	
	    } else {
	        header("Content-Length: " . $fsize);
	    }

	    $packet = 1;
	
	    if ($file) {
			while ( ! feof( $file ) && ( ! connection_aborted()) && $fsize > 0 ) {
	            if ($fsize > $buffer)
	                echo fread($file, $buffer);
	            else
	                echo fread($file, $fsize);
	            ob_flush();
	            flush();
	            $fsize -= $buffer;
	            $bandwidth += $buffer;
	            if ($speed > 0 && ($bandwidth > $speed * $packet * 1024)) {
	                sleep(1);
	                $packet++;
	            }
	        }
	        @fclose($file);
	    }

		update_post_meta( $attachment_id, '_da_downloads', (int) get_post_meta( $attachment_id, '_da_downloads', true ) + 1 );

		die();
	} else {
		return false;
	}
}

Oh, and forgot to mention, Chrome on OSX works just fine…