row = copy.copy(row)

    # Inject other meta fields (%title, %genre, %playing, %format, etc.)
    rx_keys = "[\$\%](" + "|".join(row.keys()) + ")\\b"
    cmd = re.sub(rx_keys, lambda m: "%r" % str(row.get(m.group(1))), cmd)

    # Add default %pls if cmd has no %url placeholder
    if not add_default and cmd.find("%") < 0:
        cmd = cmd + " %pls"
        # "pls" as default requires no conversion for most channels, and seems broadly supported by players

    # Playlist type placeholders (%pls, %m3u, %xspf, etc.)
    for dest, rx in placeholder_map.items():
        if re.search(rx, cmd, re.X):
            # no conversion