custom code in functions.php overrides data on all posts

I have a problem with my code that’s in my functions.php. What it does is that I provide it an mp3 file, it gets the length in bytes and the time. When I save the post, it saves the data in a custom field.

Problem I having is that data from the last post will save it to all posts, overriding data that was already saved.

I’m looking for a way to save that data to a post and not it override all posts when a post is saved.

function analyize_mp3_add_meta_box() {
	add_meta_box(
		'analyize_mp3-analyize-mp3',
		__( 'Analyize MP3', 'analyize_mp3' ),
		'analyize_mp3_html',
		'post',
		'normal',
		'default'
	);
}
add_action( 'add_meta_boxes', 'analyize_mp3_add_meta_box' );
function analyize_mp3_html( $post) {
wp_nonce_field( '_analyize_mp3_nonce', 'analyize_mp3_nonce' ); ?>
<style type="text/css">
    audio {display: none;}
</style>
<script type='text/javascript'>//<![CDATA[
    jQuery(function(){
    var objectUrl;
    jQuery("#audio").on("canplaythrough", function(e){
        var seconds = e.currentTarget.duration;
        var duration = moment.duration(seconds, "seconds");
        var hours = duration.hours();
        var mins = duration.minutes();
        var secs = duration.seconds();
        if (hours < 10) { time_hour = "0" + hours + ":" ; } else { time_hour = hours + ":" ;};
        if (mins < 10) { time_mins = "0" + mins + ":" ; } else { time_mins = mins + ":" ;};
        if (secs < 10) { time_secs = "0" + secs} else { time_secs = secs};
        jQuery("#duration").text(time_hour+time_mins+time_secs);
        jQuery('#timelength').val(time_hour+time_mins+time_secs);
        URL.revokeObjectURL(objectUrl);
    });
    jQuery("#file").change(function(e){
        var file = e.currentTarget.files[0];
        jQuery("#filesize").text(file.size);
        jQuery('#size').val(file.size);
        objectUrl = URL.createObjectURL(file);
        jQuery("#audio").prop("src", objectUrl);
    });
    });//]]> 
</script>    
<input type="file" id="file" />    
<audio id="audio"></audio>    
<p>
    <label>File Size:</label>
    <span id="filesize"></span>
    <input type="hidden" id="size" name="size" value=""/>
</p>    
<p>
    <label>Song Duration:</label>
    <span id="duration"></span>
    <input type="hidden" id="timelength" name="time" value=""/>
</p>        
<?php }
function analyize_mp3_save_w_analy( $post_id ) {
        if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) return;
        if ( ! isset( $_POST['analyize_mp3_nonce'] ) || ! wp_verify_nonce( $_POST['analyize_mp3_nonce'], '_analyize_mp3_nonce' ) ) return;
        if ( ! current_user_can( 'edit_post', $post_id ) ) return;
        if ( isset( $_POST['size'] ) )
        if (!empty(sanitize_text_field($_POST["size"]))) {;
            update_post_meta( $post_id, 'length', sanitize_text_field( $_POST['size'] ));
        };
        if ( isset( $_POST['time'] ) )
        if (!empty(sanitize_text_field($_POST["time"]))) {;
            update_post_meta( $post_id, 'time', sanitize_text_field( $_POST['time'] ));
        };
        $url = str_replace(array('http://','https://'), 'dts.podtrac.com/redirect.mp3/', get_post_meta( get_the_ID(), 'podcast_url', true ));
        $podcast_check = get_post_meta( get_the_ID(), 'podcast_url', true );
        if ($url && get_post_meta( $post_id, 'podcast_url', true ) !== $url) {
            update_post_meta( $post_id, 'podcast_url', $url );
        }
}
add_action( 'save_post', 'analyize_mp3_save_w_analy' );