static void writer_print_ts(WriterContext *wctx, const char *key, int64_t ts, int is_duration)
{
    if ((!is_duration && ts == AV_NOPTS_VALUE) || (is_duration && ts == 0)) {
        writer_print_string(wctx, key, "N/A", PRINT_STRING_OPT);
    } else {
        writer_print_integer(wctx, key, ts);
    }
}
static void writer_print_ts(WriterContext *wctx, const char *key, int64_t ts, int is_duration)
{
    if ((!is_duration && ts == AV_NOPTS_VALUE) || (is_duration && ts == 0)) {
        writer_print_string(wctx, key, "N/A", PRINT_STRING_OPT);
    } else {
        writer_print_integer(wctx, key, ts);
    }
}